Keystone Coal Mining Corporation

Read the official release (fmshrc.gov)

Plain-English summary

This consolidated decision concerns thousands of respirable-dust sample citations issued to coal mine operators after MSHA identified abnormal white centers on dust filters. The Commission affirmed the ALJ's common-issues and Keystone decisions, holding that an abnormal white center alone did not prove deliberate tampering or a violation of the cited rule. It also vacated the 75 Keystone citations because the Secretary did not prove that Keystone intentionally altered the cited filters. The ruling established the abnormal-white-center holding for the stayed dust cases and directed the Chief ALJ to set a schedule for those cases.

Decision snapshot

• Cited standards: 30 C.F.R. § 70.209(b), 30 C.F.R. § 71.209(b), and 30 C.F.R. § 90.209(b)
• Outcome: The Commission affirmed the common-issues and Keystone ALJ decisions, vacated the 75 Keystone citations, and ordered further scheduling for stayed cases.
• Key point: An abnormal white center on a respirable-dust filter does not, by itself, prove deliberate alteration or a violation.

Full text (FMSHRC public release)

FEDERAL MINE SAFETY AND HEALTH REVIEW COMMISSION
1730 K STREET N.W., 6TH FLOOR
WASHINGTON, D.C. 20006

November 29, 1995

IN RE: CONTESTS OF RESPIRABLE : Master Docket No. 91-1
DUST SAMPLE ALTERATION :
CITATIONS :
:
KEYSTONE COAL MINING CORPORATION : Docket Nos. PENN 91-451-R through
: PENN 91-503-R
v. :
: Docket Nos. PENN 91-1176-R through
SECRETARY OF LABOR, : PENN 91-1197-R
MINE SAFETY AND HEALTH :
ADMINISTRATION (MSHA) :
:
SECRETARY OF LABOR, : Docket Nos. PENN 91-1264 through
MINE SAFETY AND HEALTH : PENN 91-1266
ADMINISTRATION (MSHA) :
: and
v. :
: Docket No. PENN 92-182
KEYSTONE COAL MINING CORPORATION : Docket No. PENN 92-183
:
JIM WALTER RESOURCES, :
INC., et al., :
Intervenors :
:
UNITED MINE WORKERS :
OF AMERICA (UMWA), :
Representative of Miners :

BEFORE: Doyle, Holen and Marks, Commissioners1

DECISION

BY: Doyle and Holen, Commissioners

This proceeding arises under the Federal Mine Safety and Health Act of 1977, 30 U.S.C.

1
Chairman Jordan has recused herself in this matter. Pursuant to section 113(c) of the
Federal Mine Safety and Health Act of 1977, 30 U.S.C. ' 823(c), we have designated ourselves a
panel of three Commissioners to exercise the powers of the Commission in this matter.

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' 801 et seq. (1988) (AMine Act@ or AAct@). Section 202(a) of the Mine Act requires coal mine
operators to take accurate samples of the respirable dust in the mine atmosphere to which each
miner is exposed.2 30 U.S.C. ' 842(a). This proceeding involves 3,460 citations3 issued by the
Department of Labor=s Mine Safety and Health Administration (AMSHA@) to coal mine operators
across the country, each of which alleges a violation of 30 C.F.R. '' 70.209(b), 71.209(b), or
90.209(b) (collectively, Asection 209(b)@), for tampering with and altering the weight of respirable
dust samples (ADust Cases@). 4

The Dust Cases were assigned to Administrative Law Judge James A. Broderick, who
consolidated them for a trial of the issue common to all citations, i.e., whether the appearance of
an abnormal white center (AAWC@) on a respirable dust sample filter establishes that the mine

2
The Mine Act and mandatory standards require each operator to maintain an average
concentration of respirable dust in the mine atmosphere at or below 2.0 milligrams of respirable
dust per cubic meter of air. 30 U.S.C. ' 842(b); 30 C.F.R. '' 70.100, 71.100. Under certain
circumstances, it must be maintained at or below 1.0 milligrams. See, e.g., 30 C.F.R. ' 90.100.
3
An additional 110 contested citations are on stay pending resolution of the Common
Issues case. Approximately 5,000 citations were issued in total. Not all, however, were
contested and some were settled.
4
Section 209(b) of 30 C.F.R. Parts 70, 71, and 90 provides:

The operator shall not open or tamper with the seal of any filter
cassette or alter the weight of any filter cassette before or after it is used to
fulfill the requirements of this part.

2

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operator had intentionally altered it. The judge found that the Secretary had failed to prove by a
preponderance of the evidence that an AWC on a filter establishes that the operator had altered
the weight or that deliberate conduct was the only reasonable cause of an AWC. In re: Contests
of Respirable Dust Sample Alteration Citations, 15 FMSHRC 1456, 1521-22 (July 1993) (ALJ)
(ACommon Issues Decision@). The judge then ordered a trial on the citations issued to a single
mine, the Urling No. 1 Mine (AUrling@), operated by Keystone Coal Mining Corporation
(AKeystone@). In that case, the judge held that the Secretary of Labor had failed to carry his
burden of proving by a preponderance of the evidence that the weight of the 75 cited filters had
been intentionally altered by the operator. Keystone Coal Mining Corp., 16 FMSHRC 857, 903
(April 1994) (ALJ) (AKeystone Decision@).5

The Secretary filed with the Commission a petition for discretionary review (APDR@)
seeking review of the decisions and asserting 14 points of error by the judge. Among the
Secretary=s assignments of error was his challenge to the judge=s articulation and application of
the standard of proof in both the Common Issues Decision and in the Keystone Decision and his
claim that, if the proper standard had been used, the Secretary would have prevailed in both cases.

5
The United Mine Workers of America (AUMWA@) participated in both proceedings as
representative of miners but did not submit briefs to the judge.

3

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The Commission granted the Secretary=s PDR and granted intervenor status to a number
of mine operators (the AIntervenors@). The parties and Intervenors submitted briefs and the
Commission heard oral argument.6 After careful review of the record, and for the reasons that
follow, we affirm the judge=s decisions.

I.

Background and Judge=s Decisions

A. Factual and Procedural History in Common Issues

Coal mine operators are required to submit accurate dust samples on filter cassettes to
MSHA for measurement of the quantity of respirable coal dust in the mine atmosphere. 15
FMSHRC at 1457; 30 C.F.R. '' 70.201-220, 71.201-220, and 90.201-220. These samples are
taken in a sampling unit, consisting of a pump, hose, cyclone assembly, and plastic cassette,
manufactured by the Mine Safety Appliance Corporation (AMSA@). 15 FMSHRC at 1457. The
pump draws air into the cyclone assembly, which separates out larger dust particles. Air
containing respirable dust particles is directed into the plastic cassette, which contains a capsule
consisting of an aluminum foil cone, a filter, and a backing pad. Id. Airborne particles are
deposited on the filter face. Id. The cassette is removed from the sampling unit and sent to
MSHA=s weighing laboratory along with a card providing information on the sample (Adust data
card@). Id. At the weighing laboratory, MSHA technicians open the sealed cassette, remove and
desiccate the capsule, and then weigh it to determine whether the respirable dust concentration is
in compliance with the levels required by 30 C.F.R. '' 70.100, 71.100, and 90.100. See id.

6
The UMWA filed an appearance but did not submit briefs to the Commission or
participate in oral argument.

4

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In 1983, Mr. Robert Thaxton, then an industrial hygienist at MSHA=s District Office in
Mt. Hope, West Virginia, subjected 25 to 50 dust filter cassettes to reverse air flow tests by
blowing or otherwise directing air into the outlet of the cassette to determine the potential for
removal of dust by tampering. Id. at 1457-58; Tr. 108-10. The resulting filters exhibited white
circular areas in the center. 15 FMSHRC at 1458. In February 1989, a laboratory technician at
Mt. Hope noticed a protruding filter on a cassette submitted by Peabody Coal Company
(APeabody@). Id.; Tr. 327-28.7 When the foil was removed, a sharply defined circular white
center that was aligned with the aluminum foil inlet opening of the filter capsule was visible on the
filter. Tr. 329, 336-37. Mr. Thaxton, the supervisory industrial hygienist at Mt. Hope, regarded
this filter appearance as abnormal and believed that the Peabody filter resembled some of his 1983
experimental filters. 15 FMSHRC at 1457-58; Tr. 108-10, 330-31. Filters with this abnormal
white center appearance were termed AWCs. 15 FMSHRC at 1458.

The Pittsburgh Health Technology Center (APHTC@), MSHA=s main laboratory, began to
examine all filters from that same Peabody mine and, later, from all Peabody mines. Id.; Tr. 337-

38. In August 1989, MSHA=s investigation expanded to include all filters submitted by coal mine
    operators nationwide. 15 FMSHRC at 1458; Tr. 342. Filters were examined for abnormalities
    and those with suspected AWCs were forwarded to Thaxton at the Mt. Hope facility. 15
    FMSHRC at 1458; Tr. 128-29, 339.

On March 19, 1990, MSHA initiated an AWC Avoid code@8 and began rejecting respirable
dust samples that exhibited AWCs. 15 FMSHRC at 1460; R. Ex. 1400, at 12. On April 4 and
June 7, 1991, MSHA issued approximately 4,700 citations to approximately 847 mines and
proposed civil penalty assessments totaling about $6.5 million.9 See 15 FMSHRC at 1460; Tr. 3
(Prehr=g Conf. June 19, 1991). The citations were issued by MSHA inspectors, but Thaxton
alone determined whether a particular filter was to be cited. 15 FMSHRC at 1460. Each
citation charged the mine operator with violating the provisions of section 209(b) and alleged that
Athe weight of the respirable dust cassette . . . has been altered while the cassette was being
submitted to fulfill the sampling requirements . . . .@ Id. Each citation characterized the level of
the operator=s negligence as Areckless disregard,@ and the Narrative Findings for a Special

7
ATr.@ refers to transcript of the Common Issues trial. AK. Tr.@ refers to the transcript of
the trial in Keystone. AR. Ex.@ refers to Respondent Exhibits and AGov=t Ex.@ to Government
Exhibits introduced at the Common Issues trial. AK. Ex.@ refers to Keystone Exhibits and AK.
Gov=t Ex.@ to Government Exhibits introduced at the Keystone trial. AOral Arg. Tr.@ refers to the
transcript of oral argument held before the Commission on March 29, 1995.
8
A void code is a three-letter code indicating that MSHA will not accept the respirable
dust sample for use in determining compliance with the respirable dust standards. Tr. 848.
9
MSHA continued to cite operators for AWCs. By the time of the Common Issues trial,
approximately 370 additional citations had been issued. The last contested citation, now on stay,
was issued on April 6, 1993.

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Assessment (ASpecial Assessment Findings@) attached to the citation stated that A[t]he violations
resulted from an intentional act of altering the dust samples.@ See, e.g., Citation dated April 4,
1991, and Special Assessment Findings dated June 12, 1991, issued to Keystone; see also 14
FMSHRC at 1512.

The cases in this proceeding arose from citations contested by operators and petitions for
assessment of penalty filed by MSHA. Extensive discovery was conducted and the parties twice
sought interlocutory Commission review of pretrial matters. In a pretrial order issued on
August 13, 1992 (AAugust 1992 Order@), Judge Broderick, citing the time and expense of trying
each case separately and relying on the Manual for Complex Litigation,10 consolidated the cases
for trial of the issue common to all cases and appointed a Lead Defense Counsel Committee to
participate in the trial on behalf of all operators. 14 FMSHRC 1510, 1511, 1516 (August 1992)
(ALJ). In the same order, the judge rejected the Secretary=s argument that, if he proved that the
weight of a dust sample had been altered, he need not prove that the alteration was deliberate. Id.
at 1515. The judge concluded that the plain words of section 209(b) do not give rise to a
violation based on accidental or unintentional altering of the cassette=s weight. Id. at 1515-16.
Rather, the judge found that a violation necessarily included an intentional action on the part of
the mine operator. Id. at 1515. The judge set forth the issue to be determined as: A[w]hether an
abnormal white center (AWC) on a cited filter cassette establishes that the operator intentionally
altered the weight of the filter?@ Id. at 1517. The judge stated, Athe Secretary has the burden of
establishing [his] case by the preponderance of the evidence.@ Id.

B. Common Issues Trial

The Common Issues trial commenced on December 1, 1992, and concluded on

10
AActions pending in the same court involving common questions of law or fact may be
consolidated under Fed. R. Civ. P. 42(a) for trial or pretrial if it will avoid unnecessary cost or
delay.@ Manual for Complex Litigation ' 21.631 (1995) (supplement to James W. Moore et al.;
Moore=s Federal Practice (2d ed.)).

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February 22, 1993. Mr. Thaxton testified for eight days on his AWC classification and the
potential causes of AWC formation. Thaxton had developed ten Atamper codes@ to describe the
various AWC appearances. 15 FMSHRC at 1460-62; Tr. 168-71; R. Ex. 1064. Approximately
97% of the cited filters were originally classified under tamper codes 1, 2 or 3.11 15 FMSHRC at
1462. Filters originally suspected of having AWCs, but which Thaxton decided should not be
cited, were termed Ano-calls.@ Id. at 1460; Tr. 129-31. In March 1992, Thaxton reexamined the
cited filters and reclassified 464 filters; 95% of the cited filters remained as tamper code 1, 2 or 3.
15 FMSHRC at 1462. In his opinion, AWCs resulted from acts of intentional alteration by mine
operators, primarily by the application of reverse air through the filters. Tr. 183, 191, 209, 598-

99. Lewis Raymond, Chief of the Weighing Branch, Dust Division of the PHTC, testified on the
    handling and screening practices of filters exhibiting AWCs. The Secretary offered the scientific
    testimony of Dr. Virgil Marple and his colleague, Dr. Kenneth Rubow, who had conducted
    experiments involving AWCs, including application of reverse air flow to filter cassettes and
    dropping cassettes and pumps. 15 FMSHRC at 1474-83. Dr. Marple concluded that the most
    probable cause of AWC dust dislodgment was the deliberate application of reverse air flow. Id. at
    1469-70, 1481; Gov=t Ex. 280, at 4-7, 57, 103-05; Gov=t Ex. 282, at App. A; Tr. 2590, 2597-98.
    The Secretary=s statistical expert, Dr. John J. Miller, testified that AWCs were not random across
    all coal mines. 15 FMSHRC at 1485, 1488; Tr. 3721-23. According to Dr. Miller, there was a
    marked decline in AWCs after MSHA=s initiation of the AWC void code on or about March 19,
100. 15 FMSHRC at 1486, 1488; Tr. 3723-24. Miller also testified that the decrease in the rate
     of cited AWCs was not explained by the dates on which filters were manufactured. 15 FMSHRC
     at 1486-88.

The operators offered the scientific testimony of Dr. Richard J. Lee, who also classified
the cited filters into groups based on appearance. Id. at 1470-71. Dr. Lee performed a series of
dust dislodgment tests and concluded that AWCs can result from accidental and incidental events.
Id. at 1488-96; Tr. 6531-34. He testified that manufacturing variations in the sampling units,
such as a shorter filter-to-foil distance12 in the cassette and the pliability of the hose, increase
11
Filters classified under tamper code 1, termed by Thaxton as Alight cleaned,@ were
described as containing a white ring in the center of the filter, approximately 6 millimeters (Amm@)
in diameter, directly aligned with the cassette inlet. The appearance of the center portion of the
ring was not markedly lighter. In Thaxton=s opinion, tamper code 1 AWCs resulted from reverse
air flow. 15 FMSHRC at 1461; Tr. 179-181, 183; R. Ex. 1064. Filters classified under tamper
code 2, Acleaned,@ were described as exhibiting a markedly lighter dust deposit within the circular
area. Thaxton believed that tamper code 2 AWCs also resulted from reverse air flow. 15
FMSHRC at 1461; Tr. 184-85, 191, 193-98, 767-68, 776; R. Ex. 1064. Filters classified under
tamper code 3, Acleaned and coned,@ were described as similar to those classified under tamper
code 2, but exhibiting a slight rise or cone in the center. Thaxton believed that tamper code 3
AWCs resulted from Aforceful@ reverse air flow. 15 FMSHRC at 1461; Tr. 198-201, 208-09,
1258; R. Ex. 1064.
12
Filter-to-foil distance is the distance in the cassette between the filter surface and the
opening of the aluminum foil cone. Tr. 2279; R. Ex. 1001, at ii, B-8.7.

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susceptibility to AWC formation. 15 FMSHRC at 1494-95; Tr. 6534-35. The operators= other
scientific experts, Dr. R. Larry Grayson, Dr. Andrew R. McFarland, and Dr. Morton Corn,
similarly testified that AWCs can result from accidental and incidental events, such as dropping or
other impacts to sampling units and impacts to hoses of sampling units. 15 FMSHRC at 1497-99,
1505-06. Dr. McFarland conducted a courtroom demonstration in which he twice dropped a 31-
pound tool box on the hose of a sampling assembly, each time producing an AWC. Id. at 1503.
The operators= statistical expert, Dr. H. Daniel Roth, testified that the AWC citation rate declined
continuously after September 1989 and that the void code date of March 19, 1990, was not
statistically significant. Tr. 3983, 3987-88, 3994, 4001; R. Ex. 1041, at 4. Roth criticized
Miller=s analysis of filter manufacturing dates. 15 FMSHRC at 1508.

The judge observed the filters presented at the hearing. Id. at 1467. The cited and
experimental filters are not in the record but, during discovery, the operators= expert witnesses
were permitted to inspect the cited filters and each expert had the opportunity to review the
others= experimental filters. E.g., Tr. 5949, 7521; Gov=t Ex. 267, at 4-6. Photographs of the
cited filters and of many of the experimental filters are in the record. See, e.g., Gov=t Exs.
photograph albums entitled Cited Filters, vols. 1-7, set 2. Evidence concerning the practices or
circumstances of any particular mine was excluded from the Common Issues trial. 15 FMSHRC at
1464; see also id. at 1522; 16 FMSHRC at 896.

C. Common Issues Decision

The parties filed post-trial and reply briefs in April and May 1993, and the judge issued his
decision on July 20, 1993. 15 FMSHRC 1456. His findings and conclusions are as follows:

1. Burden of Proof

The judge held that the Secretary bore the burden of proving Aby a preponderance of
evidence that (1) the term >AWC= has a coherent meaning and was consistently applied; (2) the
cited AWCs can only have resulted from intentional acts; and (3) the AWCs resulted in weight
losses in the cited filters.@ 15 FMSHRC at 1463-64.

2. Mr. Thaxton=s AWC Classifications

The judge found that the term AAWC@ has a coherent meaning and refers to an Aabnormal
filter appearance in a dust sample consisting of dust dislodgment from the central portion of the
filter.@ 15 FMSHRC at 1513. He found that the classification of AWCs by Thaxton under his
tamper codes, although not perfectly consistent, was sufficiently consistent to require a
determination of whether the existence of an AWC establishes a violation. Id. at 1469, 1513.

3. Possible Causes of AWCs

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The judge determined that A[t]he dust dislodgment patterns on the cited filters classified
under tamper codes 1, 2, 3, and 713 can have resulted from intentional acts: blowing by mouth
through the cassette outlet, otherwise directing a jet or pulse of air into the cassette outlet, or
introducing a vacuum source into the cassette inlet.@ 15 FMSHRC at 1513 (emphasis added). He
also found that the dust dislodgment patterns on filters classified under these tamper codes Acan
have resulted from:

1. impacts to the cassette from dropping or striking it;

2. impacts to the hose from stepping on it, dropping an object
   on it, striking it against a wall while the hose was wrapped
   around the sampling assembly, closing a door or drawer on
   it, or sitting on it;

3. snapping together the two halves of the filter cassette.@

Id. (emphasis added).

The judge explained that, although the experts differed as to the likelihood that AWC
dislodgment patterns would result from incidental events or accidents, Athe experiments all show
that at least sometimes they do occur.@ Id. at 1513-14. He observed that dust dislodgment
patterns on many of the filters subjected to impact or snapping tests were indistinguishable from
cited AWCs. Id. at 1514. The judge concluded that the AWCs did not result from handling by
the United States Postal Service or from the PHTC=s handling or desiccation processes. Id.

The judge determined that the manufacturing characteristics of filter-to-foil distance and
filter floppiness varied from filter to filter and mine to mine. Id. at 1515, 1521. The judge found
that a filter cassette with a smaller filter-to-foil distance was more susceptible to an AWC
dislodgment pattern than one with a larger distance; that a floppy filter was more susceptible than
a taut one; and that AWC susceptibility also depended on the pliability of the sampling hose. Id.
at 1515-17. He determined that the cited filters came from a population of cassettes with shorter
filter-to-foil distances than those manufactured subsequently. Id. at 1515-16. The judge also
identified mine and dust variables that would affect dislodgment, such as type of coal, humidity in
the mine environment, weight of dust on the filter, size and shape of dust particles, and quantity of
rock dust or diesel dust on the filter. Id. at 1516-17, 1521.

13
The judge noted that Thaxton came to believe that filters classified under tamper code
7, known as Aclean tool@ and which he originally believed were created by a tool, were created by
reverse air flow. 15 FMSHRC at 1461-62, 1513; Tr. 259.

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4. Statistical Evidence

The judge found Miller=s conclusion that the AWC rate was not random across the mining
industry was not Apersuasive evidence of intentional tampering@ because of the existence of many
other potential causes. 15 FMSHRC at 1519, 1522. The judge also rejected the Secretary=s claim
that the sharp decline in cited AWCs beginning about March 19, 1990, Acan only be construed as
showing intentional misconduct@ that ceased when the operators became aware of the void code.
Id. at 1519. He reasoned that AWC citations continued, at a reduced rate, long after the void
code was instituted and after significant publicity about the criminal investigation. Id. at 1519-
20.14 The judge stated that the statistical evidence showed cassettes manufactured before January
1, 1990, had a much higher citation rate than those manufactured later, suggesting manufacturing
variables as a cause of AWC formation. Id. at 1520. The judge discounted Miller=s opinion that
there were no statistically significant relationships between dust dislodgment and filter-to-foil
distance or floppiness of filters, concluding that the weight of the scientific evidence showed that
such factors did, in fact, affect susceptibility to AWC formation. Id.

14
At the time of MSHA=s investigation of operator samples, a large number of respirable
dust samples taken by MSHA inspectors were also found to exhibit AWCs. 15 FMSHRC at
1462. Thaxton classified these samples under his tamper codes and most, but not all, were
classified under one of the reverse air flow tamper codes. Id. The judge noted evidence
indicating that the number of inspector samples exhibiting AWCs declined at about the same rate
during the relevant periods as operator samples. Id. at 1519. The Office of Inspector General of
the Labor Department investigated whether the inspectors who submitted these samples were
guilty of misconduct. The investigation was closed with no finding of misconduct, apparently
based on the finding that AWCs can result from the two parts of a cassette being snapped
together. Id. at 1462

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5. Judge=s Conclusions

Based on these findings, the judge concluded that (1) the Secretary Afailed to carry his
burden of proving by a preponderance of the evidence that an AWC on a cited filter establishes
that the mine operator intentionally altered the weight of the filter,@ and (2) the Secretary Afailed
to carry his burden of proving by a preponderance of the evidence that deliberate conduct on the
part of the cited mine operators is the only reasonable explanation for the cited AWCs.@ 15
FMSHRC at 1521. The judge emphasized that filter variables (filter-to-foil distance and
floppiness), pliability of the hose, and dust variables (type of coal, humidity, weight of dust on the
filter, size and shape of dust particles, and quantity of rock or diesel dust) affect susceptibility to
AWC formation and that Miller=s statistical analysis failed to adequately account for these
variables. Id. at 1521-22. The judge concluded that Miller=s analysis also failed to establish that
the cited AWCs were not the result of accidental occurrences or manufacturing variables. Id.
Noting that the expert testimony as to causes of AWCs was conflicting, the judge, in summary,
concluded that the record showed too many other potential causes Ato accept the Secretary=s
circumstantial evidence as sufficient to carry his burden of proof that the mine operators
intentionally altered the weight [of] the cited filters.@ Id.

The judge ordered a mine specific hearing to address the 75 AWC citations issued to
Keystone=s Urling mine. Id. at 1522. He set forth the main issue as Awhether the weight of the
filters cited as AWCs from . . . Urling . . . was intentionally altered by the mine operator@ and
stated that the burden of proof remained with the Secretary. Id. The judge stayed all other Dust
Cases. Id. at 1523.

D. Factual and Procedural History in Keystone

The Urling mine, in Indiana County, Pennsylvania, is operated by Keystone, a wholly
owned subsidiary of Rochester and Pittsburgh Coal Company (AR&P@). The dust sampling
program for all 13 R&P mines, including Urling, was conducted by R&P=s Environmental Safety
Department (AESD@), also in Indiana, Pennsylvania. 16 FMSHRC at 858-59; Stipulations by
Secretary and Keystone, No. 14, filed November 30, 1993 (AStip.@). From 1970 until his
retirement in 1991, Donald Eget, who was trained as an engineer, was the supervisor of ESD. 16
FMSHRC at 861; K. Tr. 2231-33. During 1989 and 1990, Shawn Houck worked with Eget in
the ESD laboratory as a maintenance and calibration technician. 16 FMSHRC at 861-62.
Douglas Snyder was the dust technician responsible for Urling sampling; three other dust
technicians handled sampling for R&P=s other mines. Id. at 862.

Pursuant to normal operating procedures at ESD during 1989 to 1991, the dust
technicians picked up pumps and sampling assemblies in the morning and delivered them to R&P=s
mines for use on that day=s three shifts. Id. Each morning, Eget drove to all 13 R&P mines to
retrieve pumps and samples from the previous afternoon and midnight shifts. Id. The dust
technicians returned to the ESD after 4:00 p.m., delivering pumps used during the day shift. Id. at
863.

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While Eget collected pumps, Houck processed those from the previous day shift. Id. at

862. Houck removed the sampling head15 and the hose from each pump, filled out the dust data
     cards, cleaned the sampling units, calibrated the pumps, reassembled the units, and inserted a new
     filter cassette in each one for use the next day. Id. at 862-63; K. Tr. 2103-04. When Eget
     returned to the laboratory, Houck took the cassettes into Eget=s office. 16 FMSHRC at 862.
     Eget inspected the used cassettes, recorded their identification numbers, checked the dust data
     cards against the cassette numbers, and looked into the cassette inlets and recorded the filter
     appearances in a logbook he kept for each mine. Id. at 862-63, 889. The cassettes were then
     packaged for mailing to MSHA and taken to the R&P mailroom. Id. at 863; K. Tr. 2102-03,
     2174.

Dust technician Snyder delivered pumps to Urling and distributed them to the miners or
section foremen on the day and afternoon shifts. 16 FMSHRC at 864. He left pumps for the
midnight shift. Id.

On April 4, 1991, the Secretary issued 53 citations to Urling, and on June 7, 1991, issued
22 additional citations, alleging violations of section 70.209(b). Id. at 858. Three filters
forwarded to Thaxton were determined to be no-calls. Id. at 868, 870.

E. Keystone Trial

The trial in Keystone commenced on November 30, 1993, and concluded on January 6,
1994. 16 FMSHRC at 859. Robert Thaxton testified with respect to the appearance of the
75 cited and three no-call filters. Mr. Thaxton was of the opinion that the dust dislodgment
patterns of the cited filters resulted from deliberate acts, in most cases from air blown through the
filter cassette in a reverse direction. Id. at 868-72; K. Tr. 864-66, 911-15; see K. Gov=t Ex. 505.
Dr. Marple, the Secretary=s scientific witness, also examined and classified the 78 filters. 16
FMSHRC at 872-74. Marple concluded that 71 or 72 resulted from reverse air flow, two or three
resulted from a vacuum source introduced into the cassette inlet, and one resulted from water
introduced into the filter (Marple was originally unable to ascribe a cause to that filter=s
appearance). Id. at 873, 898-99. Marple further concluded that none of the dislodgment patterns
on the Urling filters resulted from impacts to the cassettes. Id. at 873-74, 899.

15
The sampling head includes the cyclone unit and filter cassette. Tr. 91-94.

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Dr. Miller, the Secretary=s statistical expert, testified that, before March 26, 1990, the date
that MSHA alleges Urling learned of the void code, Urling had a much higher citation rate than
other mines.16 Id. at 878-79. He testified that Urling had a citation rate of 42.77% (74 cited
samples out of 173) in the period August 1989 through March 26, 1990. After March 26, the
rate fell to 0.18% (one cited out of 552). In contrast, other mines had an average citation rate of
5.96% for the earlier period. Id. at 878. Miller also testified that the date of cassette manufacture
failed to explain the differences in citation rates between Urling and other mines because Urling=s
citation rate was eight times higher than that of other mines using cassettes manufactured on the
same dates. Id. at 879.

Dr. Lee, Keystone=s scientific expert, concluded that most of the cited filters showed
comparatively slight dust dislodgments from the central area, slightly larger diameters, no cones,
and only a slight indication of dimpling, all of which indicated lesser forces than would have
occurred with deliberate reverse air flow. Id. at 876, 899. Lee testified that the appearance and
dimensions of the dislodgment patterns on the Urling filters were consistent with a mixed
mechanical pulse/reverse air pulse mode of occurrence (Amixed-mode@ theory). Id. at 876-77.17
He also testified that humidity in the mine atmosphere reduced the susceptibility to dislodgment of
dust on filters and that the introduction of water sprays and scrubbers at Urling beginning in 1989
and 1990 contributed to the decline in AWCs. K. Tr. 3891-97, 4042-44, 4087-89; see also 16
FMSHRC at 877; K. Ex. 2001, at 14.

Dr. Roth, the operators= statistical expert, testified that he examined the citation rates of
Urling and all R&P mines on a bimonthly basis and that the data showed a strong trend of
declining rates over the entire period from August 1989 to March 1992. 16 FMSHRC at 880.
Roth also testified that manufacturing variables may have been a factor in AWC formation
because the rate of cited AWCs was greater for cassettes manufactured on earlier dates compared
to later dates. Id. He concluded that R&P=s high incidence rates Amay be attributable to cassettes
manufactured on four consecutive dates, May 26, May 31, June 1, and June 2, 1989.@ Id. The
AWC citation rate of R&P mines, including Urling, for cassettes manufactured on those dates was
49.6% compared to 5.8% for other dates. Id.

16
Data from other mines consisted of data for all dust samples processed by MSHA from
August 8, 1989, through March 31, 1992, except data from R&P mines, mines whose operators
pled guilty to tampering, and mines whose cassettes may not have been examined for AWCs. 16
FMSHRC at 878.
17
Under Lee=s mixed-mode theory, two impacts may occur almost simultaneously: an
impact to the cyclone that results in a mechanical pulse to the cassette and an impact to the hose
that results in a reverse air pulse to the cassette. According to this theory, the mechanical pulse
tends to dislodge dust on the filter outside of the 6 mm ring, while the reverse air pulse tends to
dislodge dust inside the ring. See 16 FMSHRC at 876-77.

13

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Page 14

ESD personnel testified as to their involvement in the respirable dust sampling program at
Urling. Id. at 888-93.18 Eget, Houck, and Snyder denied tampering with the dust cassettes or
observing anyone else tamper with the cassettes. Id. at 890-91.

F. Keystone Decision

The parties filed post-hearing briefs in March 1994 and the judge issued his decision on
April 20, 1994. His findings and conclusions are as follows:

1. Burden of Proof

The judge held that the Secretary bore the burden of proving Aby a preponderance of the
evidence that the 75 cited Urling filters resulted from intentional tampering.@ 16 FMSHRC at

895. The judge noted that Keystone Ad[id] not have the burden of establishing that the
     appearances on the samples resulted from some other cause.@ Id. at 896. The judge reasoned that
     the Secretary, as the party bearing the burden, must convince the trier of fact Athat the existence
     of a fact is more probable than its nonexistence . . . .@ Id. at 895, quoting Concrete Pipe and
     Products of Cal., Inc. v. Construction Laborers Pension Trust for S. Cal., 508 U.S. , 113 S.
     Ct. , 124 L. Ed. 2d 539, 563 (1993). He explained that A[t]o preponderate, the evidence must
     be sufficient to convince the trier of fact that the proposition asserted is more likely true than not
     true.@ 16 FMSHRC at 895-96 (citations omitted). The judge also noted that A[a]ll of the
     evidence must be given appropriate weight, whether it be direct or circumstantial@ and that
     A[c]ircumstantial evidence may prove an ultimate fact.@ Id. at 896.

896. Possible Causes of Urling AWCs

18
Thirty-three current and former Keystone and R&P employees, including miners,
section foremen, technicians, managers, and safety department personnel, testified at the trial. All
employees who worked at the ESD laboratory during 1989 and 1990 testified. 16 FMSHRC at
888.

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Page 15

Preliminarily, the judge reviewed the evidence pertaining to the handling of dust pumps
and cassettes at the Urling mine and ESD laboratory. He found that dust dislodgment patterns on
the cited filters could have resulted in whole or in part from the handling of the sampling
equipment by Urling miners or ESD personnel. 16 FMSHRC at 864, 868. The judge found that
AWCs Acould have resulted wholly or partly@ from incidental and accidental events occurring in
the mine, such as pumps falling to the mine floor and hoses being pinched by mantrips, snagged
on other objects, or wrapped around pumps, and from other contacts to hoses.19 Id. at 868. The
judge also found that AWCs Acould have resulted wholly or partly@ from incidental and accidental
events occurring in the ESD laboratory or during transportation of the pumps, including multiple
pumps being carried by their hoses and boxes containing pumps being dropped to the floor of a
vehicle or onto a table. Id. at 861-64.

19
Some miners attached the pumps to their clothing during sampling, while others
attached them to the continuous miners. 16 FMSHRC at 866. Urling used two types of
continuous miners, Lee-Norse and Joy. Id. The judge found that the dust dislodgment patterns
could have been caused or contributed to by attachment of the sampling head to the Lee-Norse
miners, which vibrated while cutting coal. Id. at 882. However, he concluded that changes in the
dust deposition patterns on Urling filters after the void code date were not due to changes in
handling by section foremen or miner operators or helpers, although he noted that some Urling
foremen kept a closer eye on dust pumps after learning of the MSHA investigation. Id. at 882,
898.

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Page 16

The judge made findings regarding factors that could have contributed to the decline of
AWCs at Urling. Id. at 882-87. He found that changes in handling practices of ESD personnel
during the spring of 1990 could have been a factor in the reduced incidence of AWCs. Id. at 884.
He found that Eget, whose handling of the sampling equipment was rougher than that of the
others, did not handle samples from April 9 to May 10, 1990, and that Snyder and the other
technicians exercised more care in their handling of the equipment, avoiding impacts to the hoses
because of MSHA=s investigation. Id. The judge concluded that, because dust deposits were
damper and less susceptible to dislodgment when scrubbers were in use, the installation of
scrubber systems on the continuous miners at Urling beginning in 1989 could have been a factor
in the decline of AWCs. Id. at 882-83. With respect to sampling equipment, the judge found that
the Urling cassettes more probably than not had shorter filter-to-foil distances and this could have
been a factor in the decline of AWCs. Id. at 885-86.20

On the basis of his Common Issues Decision, the judge determined that the dislodgment
patterns on the Urling filters could also have resulted from intentional tampering. Id. at 898. The
judge concluded that, if tampering occurred, it must have occurred at the ESD laboratory. Id. In
resolving whether the AWCs resulted from intentional acts at ESD, the judge analyzed the
scientific and statistical evidence and evaluated the testimony and credibility of ESD employees.
Id.

3. Scientific Evidence

20
The judge determined that a number of other factors, such as changes in MSHA=s
AWC selection criteria and other mine conditions at Urling, including height of the coal seam,
roof stability, presence of a layer of rock in the coal seam, and changes in mantrips did not explain
the decline in Urling=s AWC rate. 16 FMSHRC at 882-87. The judge was unable to determine
whether the section in the mine from which dust samples were taken affected the decline of
AWCs. Id. at 883. Although he found in the Common Issues Decision that pliability of dust
pump hoses may be related to AWC formation, the judge was unable to conclude whether this
was a factor in the decline in AWCs at Urling. Id. at 886. He also noted that equipment changes
at ESD were of questionable significance. Id. at 884.

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Page 17

Based on Mr. Thaxton=s testimony, the judge concluded that the appearances of the cited
filters Adid not result from normal sampling.@ 16 FMSHRC at 897 (emphasis added). The judge
was not persuaded, however, by Thaxton=s reports and testimony asserting that the Urling AWCs
had been caused by intentional tampering. Id. The judge discounted Thaxton=s analysis as to
causation because Thaxton=s conclusions were Ato a considerable extent subjective.@ Id. His tests
were not conducted according to a written protocol based on systematic testing that related
specific dislodgment patterns to types of tampering. Id. Additionally, the judge found that the
distinction Thaxton made between cited and no-call filters was Adifficult to discern@ and Atenuous
at best.@ Id. at 870-71, 897.

The judge concluded, on the basis of the testimony of Dr. Marple and Dr. Lee, that 73 of
the cited Urling filters Aresulted in whole or in part from reverse air flow through the filter.@ Id. at
898-900. The judge credited Lee=s testimony that those filters showed comparatively slight
dislodgments from the central area, had no cones at the time the citations were issued, and had
slightly larger areas of dust dislodgment. Id. at 899. On that basis, he reasoned that the forces
responsible for the Urling AWCs were Arelatively slight@ and concluded that the reverse air forces
involved in the creation of those filters were Agenerally less@ than the force associated with
deliberate blowing through the filter cassette. Id. at 899-900. The judge also concluded that the
dust dislodgment patterns of the Urling filters Amay have been influenced@ by accidental and
incidental events involving impacts to the cassette and sampling assembly, as set forth in Dr. Lee=s
mixed-mode theory. Id. at 900; see id. at 876-77.

As to the other two cited filters, the water stain filter No. 324842 and filter No. 325300,
the judge held that the Secretary=s evidence was inconsistent and unconvincing and failed to
establish deliberate tampering. Id. at 900.

4. Statistical Evidence

The judge noted that the statistical experts, Dr. Miller and Dr. Roth, reached different
conclusions using the same data. 16 FMSHRC at 900. The judge agreed with Miller that there
was a sharp decline in Urling=s citation rate on or about March 26, 1990, the date used by Miller
in his analysis. Id. He concluded, however, that March 26, 1990, was not a logical cutoff date
for examining changes in behavior at Urling because the evidence showed that ESD personnel and
Keystone management had become aware much earlier, in February 1990, of MSHA=s
investigation of AWCs. Id. He also found that there was an overall decline in Urling=s citation
rate from September 1989 to April 1990. Id. The judge agreed with Miller that dates of
manufacture of the cassettes Ado not seem overall to explain all the differences@ in the AWC rate.
Id. at 900. On the other hand, he agreed with Roth that manufacturing anomalies may have
affected AWC formation because, as Roth showed, 60% of the cited Urling cassettes were
manufactured on four consecutive work days in May and June 1989. Id. at 900-01.

The judge was unable to conclude on the basis of the statistical evidence that the reduction
in the rate of cited filters at Urling was related to MSHA=s investigation. Id. at 901.

17

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Page 18

5. Testimony of ESD Personnel

Preliminarily, the judge recognized that a large number of mine operators and their agents
had pled guilty to criminal charges of tampering. 16 FMSHRC at 901. The judge summarized
the testimony of employees of the ESD laboratory during 1989 and 1990, all of whom were
witnesses. Id. at 888-893. He determined that only Eget and Houck had any substantial
opportunity to tamper with the samples. Id. at 901. The judge was impressed by the
backgrounds of Eget and Houck and by their forthrightness on the witness stand. Id. at 902. He
credited their statements that they had not tampered with the dust samples submitted to MSHA.
Id. at 902-03. The judge found the Secretary=s proffered motives for tampering by Eget and
Houck (to avoid penalties and resampling and the enormous cost of non-compliance) to be very
weak. Neither employee paid the R&P penalties, resampling would not have been a substantial
burden on ESD, and neither was involved in coal production or reported to a production
supervisor. Id. at 902. He noted that they knew that tampering was illegal and that Eget, at least,
was aware that criminal sanctions could result from tampering. Id. For the same reasons, he also
accepted as true the statements of the other dust technicians that they did not tamper with the
dust cassettes and further noted that they had little opportunity to tamper. Id. at 901, 903.

Overall, the judge credited the testimony of ESD personnel, expressly taking into
consideration the evidence concerning handling of dust samples at the mine and the testimony of
Thaxton, the scientists, and the statisticians. Id. at 903. He considered credibility determinations
with respect to ESD personnel to be of primary importance in his decision. Id.

6. Judge=s Conclusions

Based on the records in the Common Issues and Keystone trials, the judge concluded that
the Secretary Afailed to carry his burden of proving by a preponderance of the evidence that the
weight of the 75 cited Urling filters was intentionally altered by Keystone.@ 16 FMSHRC at 903.
Accordingly, he vacated the Urling citations, denied the Secretary=s petitions for civil penalties,
and dismissed the proceedings. Id. The judge stayed all other Dust Cases until further order of
the Commission. Id.

II.

Disposition

A. Introduction

In his PDR, the Secretary sets forth 14 points of error. He asserts that, in the Common
Issues trial, the judge imposed an improper burden of proof, which he also applied in Keystone.
In addition, he contends that the judge made incorrect scientific, statistical, and credibility

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Page 19

determinations as well as erroneous procedural rulings. The Secretary places the following issues
in contention and numbers them in the PDR as follows:

1. The judge misstated and misapplied the burden of proof in both proceedings. His use
   of the wrong burden in the Common Issues Decision fatally tainted his analysis in Keystone. PDR
   at 10-12 (addressed in section B., slip op. at 17).

2. The judge erred in failing to credit the opinions of Mr. Thaxton and Dr. Marple that
   AWCs were more consistent with deliberate application of reverse air flow through filters than
   with accidental events. PDR at 12 (addressed in section C. 2., slip op. at 26).

3. The judge erred in crediting Dr. Lee=s opinion that AWCs were more consistent with
   accidental impact forces than with tampering. PDR at 12-14 (addressed in section C. 3., slip op.
   at 29).

4. The judge erred in admitting the testimony of Dr. Corn because his testimony was
   improperly withheld from the Secretary during discovery. PDR at 14 (addressed in section C. 4.,
   slip op. at 34).

5. The judge erred in relying upon the conclusions of Dr. Corn as to accidental causation
   of AWCs because they lacked scientific foundation. PDR at 14 (addressed in section C. 4., slip
   op. at 34).

6. The judge erred in Keystone in failing to give weight to evidence regarding the optional
   quartz sampling program. PDR at 14 (addressed in section F. 2., slip op. at 59).

7. The judge erred in failing to appreciate that the statistical evidence supported
   intentional tampering as the likely cause of AWC formation. PDR at 15-16 (addressed in section
   D., slip op. at 47).

8. The judge erred in his analysis of the statistical evidence in Keystone in focusing on
   bimonthly sampling periods instead of on March 26, 1990, as the pertinent date for evaluating the
   rates of AWCs. PDR at 16 (addressed in section D. 2. b., slip op. at 55).

9. The judge erred in finding that Afilter-to-foil@ distance and other manufacturing
   variables affected the likelihood of AWC formation. PDR at 16 (addressed in section C. 5., slip
   op. at 37).

10. The judge erred in Keystone in admitting the testimony of Dr. Lee regarding water
    sprays and scrubber systems because it was improperly withheld from the Secretary during
    discovery. PDR at 17 (addressed in section C. 6., slip op. at 44).

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Page 20

11. The judge erred in Keystone in crediting the opinion of Dr. Lee over that of Dr.
    Marple concerning the effects of water sprays and scrubber systems. PDR at 17 (addressed in
    section C. 6., slip op. at 44).

12. The judge erred in concluding in Keystone that handling changes by the ESD
    personnel explained a decline in AWCs on or about March 26, 1990. PDR at 18 (addressed in
    section F. 1., slip op. at 58).

13. The judge erred in Keystone in his analysis of the credibility of the ESD witnesses.
    PDR at 18-20 (addressed in section F. 3., slip op. at 60).

14. The judge erred in excluding evidence of criminal tampering with dust samples by
    other individuals and entities. PDR at 20-21 (addressed in section E., slip op. at 55).

B. Burden of Proof21

1. Judge=s Conclusions

The judge, in the Common Issues Decision, set forth his conclusion that the Secretary had
failed to carry his burden of proving, by a preponderance of the evidence, that an AWC
established that the operator Ahad intentionally altered the weight of the filter@ or that Adeliberate
conduct on the part of the cited mine operators is the only reasonable explanation for the cited
AWCs.@ 15 FMSHRC at 1521.

In the Keystone Decision, the judge, noting that the burden of proof was the same as in the
Common Issues Decision, set forth his conclusion that the Secretary had the burden of proving,
by a preponderance of the evidence, that the Urling filters resulted from intentional tampering. 16
FMSHRC at 895.

2. Parties= Contentions

The Secretary contends that the judge imposed an improper burden of proof in both
proceedings. PDR at 10-12. He argues that the judge erred in the Common Issues Decision in
requiring him to prove that Adeliberate conduct on the part of the cited mine operators is the only
reasonable explanation for the cited AWCs.@ 15 FMSHRC at 1521 (emphasis added); PDR at 7.
The Secretary asserts that this is a burden of proof greater than the preponderance of evidence
standard and that the judge required the Secretary to prove that there was no contradictory
evidence or explanation regarding the basic propositions the Secretary sought to establish. S. Br.
at 30-35.22 The Secretary asserts that, by using the Aonly reasonable cause@ formulation, the judge
21
This section addresses Issue No. 1 in the PDR.
22
AS. Br.@ refers to the Secretary=s Brief, filed September 26, 1994. AS. Reply Br.@ refers
to the Secretary=s Reply Brief, filed December 23, 1994. AK. Br.@ refers to Keystone=s Brief, filed

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Page 21

imposed a burden of proof that was greater than the burden in criminal cases. Id. at 31-32; Oral
Arg. Tr. 208-09. The Secretary argues that, under the preponderance standard, he should have
been required to show only that the propositions sought to be established were more likely true
than not. S. Br. at 32; S. Reply Br. at 2-3.

November 14, 1994. AI. Br.@ refers to Respondent Intervenors= Brief, filed November 23, 1994.
AS. P.H. Br. (C.I.)@ refers to the Secretary=s Posthearing Brief, filed April 30, 1993, after the
Common Issues trial.

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Page 22

Keystone and the Intervenors respond that the judge explicitly adopted the preponderance
standard in his decisions and properly applied that standard. They argue that the Secretary has
confused the burden of proof with the issue to be decided in the Common Issues trial, i.e.,
whether AWCs could only have resulted from deliberate acts. They assert that the judge properly
found that the evidence did not support a finding that intentional tampering was the only
reasonable explanation. K. Br. at 12-19; I. Br. at 20-25.

3. Development of the Common Issue

On July 1, 1992, a group of operators moved for consolidation of all Dust Cases for
purposes of a separate trial on the issue of causation of AWCs. They asserted that the basic issue
common to all the citations was whether Athe existence of an AWC dispositively prove[d] that an
operator intentionally altered the weight of a respirable dust sample.@ Contestants= Mot. for Cons.
and Separate Trial at 2. The Secretary opposed the consolidation as well as the operators=
statement of the issue. S. Statement in Opp=n to Contestants= Mot. for Cons. filed July 15, 1992
(AS. Opp=n@), at 1-2.

At a pretrial conference on July 17, 1992, the Secretary=s counsel requested a Abellwether@
trial involving a large company with a number of citations. Tr. 6, 11-12 (Prehr=g Conf. July 17,
1992). The Secretary contended that it was imperative to resolve the standard of proof and how
Athe issue is to be framed within that standard of proof.@ Id. at 33. The Secretary argued that the
major issue in the proceedings was whether the weight of a cited filter had been altered while in
the custody or control of the operator and maintained that the issue of whether a deliberate or
accidental act caused the alteration was relevant only to the penalty. Id. at 27-28. The operators
responded that, in order to establish a violation under the cited regulatory provisions, the
Secretary had to establish a deliberate act by the operator. Id. at 40.

The Secretary subsequently withdrew his opposition to a common issues trial. S.
Statement of the Issues and Trial Proposal filed Aug. 7, 1992 (AS. Statement@) at 1. The
Secretary urged that, in order to be useful, the common issues trial must include all operators and
be binding on all parties. Id. at 13. As before, the Secretary argued that, to prove a violation, he
was not required to prove that intentional tampering occurred but only that a weight alteration
occurred while the filter was within the operator=s control.23 Id. at 3-10. The operators again

23
The Secretary asserted that three issues should be determined: (1) whether it was
established, by a preponderance of the evidence, that the weight of the cited filters was altered;
(2) whether it was established, by a preponderance of the evidence, that the weight alteration
occurred while the samples were in the control of the operator; and (3) whether the proposed

22

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Page 23

asserted that the issue to be determined was whether an AWC proved that an operator
intentionally altered the weight of a respirable dust filter. Contestants= Br. in Resp. to Judge=s
Prehr=g Conf. filed Aug. 7, 1992, at 28.

penalty was appropriate in light of the level of negligence exhibited. S. Statement at 2.

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Page 24

In the August 1992 Order, the judge noted the sharp disagreement that had emerged
recently between the parties as to the basic issue presented for resolution. 14 FMSHRC at 1511.
He also stated that Awhatever [the Secretary=s] position on what is necessary to prove a violation
of the standard in the abstract, [he] has clearly taken the position . . . that the violations resulted
from deliberate acts.@24 Id. at 1513. Rejecting the Secretary=s assertion that he should not be

24
As support for this statement, the judge referenced the citations, in which the Secretary
uniformly alleged the operators= negligence level as Areckless disregard,@ and his proposed
penalties, which ranged from $1,000 to $1,800 for violations of sections 70.209(b) and 71.209(b)
and $10,000 for each violation of section 90.209(b). 14 FMSHRC at 1512. (In his closing
arguments in Keystone, the Secretary argued for a fine of $5,000 for each violation of section
70.209 (b). K. Tr. 4321.) The judge also noted that, in his Response to the First Set of
Interrogatories, dated January 10, 1992, propounded by Utah Power and Light Co. (AResp. to
Interrog.@), the Secretary responded affirmatively to the question: AState whether it is the
Secretary=s contention that the alleged AWC on the cited sample could not occur in any manner
other than by the intentional act of an individual.@ 14 FMSHRC at 1513, citing Resp. to Interrog.
No. 17(h) at 12. In addition, the judge relied on Thaxton=s deposition testimony:

Q. Okay. So that you believe that the phenomenon
described in those citations resulted from deliberate
dust removal; correct?

A. It resulted from a deliberate act, yes.

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Page 25

required to prove intentional conduct, the judge found that, by the plain meaning of section
209(b), a violation was established by proving that an operator intentionally altered the dust on a
filter. Id. at 1513-16. He held that, Aas a matter of law the accidental, unintentional altering
(changing, reducing) the weight of a filter cassette while the cassette is in the custody of the mine
operator is not a violation . . . .@ Id. at 1515-16. Citing the burden of trying each case separately,
the judge consolidated the Dust Cases for the purpose of trying the issue common to all. Id. at
1511. The judge delineated the issue to be determined as A[w]hether an abnormal white center
(AWC) on a cited filter cassette establishes that the operator intentionally altered the weight of
the filter,@ and further specified that Athe Secretary has the burden of establishing [his] case by the
preponderance of the evidence.@ Id. at 1517.

On August 24, 1992, the Secretary filed a Motion for Reconsideration and Clarification of
the August 1992 Order (AS. Mot. for Recons.@), in which he challenged the judge=s interpretation
of the Secretary=s regulations to require proof of intentional conduct. S. Mot. for Recons. at 2-3,
6.

In a September 8, 1992, order (ASeptember 1992 Order@), the judge denied the motion for
reconsideration and repeated his conclusion that Athe accidental, unintentional altering (changing,
reducing) the weight of a filter cassette while the cassette is in the custody of the mine operator is
not a violation . . . .@ 14 FMSHRC 1675, 1676 (September 1992) (ALJ). The judge stated:

The purpose of the common issues trial is to receive evidence
concerning this allegation [so] that I may determine whether or not
the AWCs on the cited filters can only have resulted from such
deliberate acts. (emphasis added).

Id. at 1677. At the outset of the Common Issues trial, the judge again stated that, to prevail, the
Secretary must prove, by a preponderance of the evidence, that an AWC establishes that the mine
operator intentionally altered the weight of the filter. Tr. 7.

The Secretary did not appeal, either in a petition for interlocutory review (29 C.F.R.
' 2700.76) or in his PDR giving rise to this proceeding, the judge=s ruling that, in order to prove a
violation, the Secretary was required to prove deliberate acts. Section 113(d)(2)(A)(iii) provides:
AIf [petitions for review are] granted, review shall be limited to the questions raised by the
petition.@ 30 U.S.C. ' 823(d)(2)(A)(iii). Consequently, that determination is not in issue in this
proceeding.

4. Judge=s Formulation and Application of the Burden of Proof

a. Applicable Legal Principles

14 FMSHRC at 1513-14, quoting Thaxton Deposition (July 25, 1991) at 310-12.

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The Mine Act imposes on the Secretary the burden of proving each alleged violation by a
preponderance of the credible evidence. Garden Creek Pocahontas Co., 11 FMSHRC 2148,
2152 (November 1989). The preponderance standard, in general, means proof that something is
more likely so than not so. See 3 Edward J. Devitt et al., Federal Jury Practice and Instructions
' 72.01 (1987); 2 Kenneth S. Brown et al., McCormick On Evidence ' 339, at 439 (4th ed.
1992); Hopkins v. Price Waterhouse, 737 F. Supp. 1202, 1206 (D.D.C. 1990). The Supreme
Court, in Concrete Pipe, 124 L. Ed. 2d at 563, relied on by the judge, 16 FMSHRC at 895,
explained that A[t]he burden of showing something by a >preponderance of the evidence,= the most
common standard in the civil law, simply requires the trier of fact >to believe that the existence of
a fact is more probable than its nonexistence before [he] may find in favor of the party who has
the burden to persuade the [judge] of the fact=s existence.=@ See also 2 McCormick ' 339, at 439
n.12, citing Model Code of Evidence, Rules 1(3) & (5).

b. Burden of Proof in Common Issues Decision

The Common Issues Decision fully supports the judge=s application of the proper burden
of proof. We find that, in his rulings prior to and during the trial as well as in his decision, the
judge appropriately articulated the appropriate burden. Based on our review of the record, we

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conclude that the judge also properly applied the burden. Further, the judge=s use of the phrase
Aonly reasonable explanation@ addressed the Secretary=s argument, not the burden of proof.

In the September 1992 Order, the judge ordered the Common Issues trial to receive
evidence on which to base a determination of whether AWCs can only have resulted from
deliberate conduct. 14 FMSHRC at 1677. At the commencement of the trial, the judge stated
that, in order to prevail, the Secretary must prove by a preponderance of the evidence that dust
cassettes with AWCs were caused by mine operators intentionally altering their weight. Tr. 7.
The Secretary, in his Posthearing Brief and Proposed Findings of Fact, argued that he had
established that the Aonly reasonable explanation@ for the AWCs was intentional tampering.
S.P.H. Br. (C.I.) at 1-2, 224.

In his decision, the judge reiterated that the ASecretary has the burden of proof@ and that
this burden requires that the Secretary prove by a Apreponderance of the evidence that (1) the
term >AWC= has a coherent meaning and was consistently applied; (2) the cited AWCs can only
have resulted from intentional acts; and (3) the AWCs resulted in weight losses in the cited
filters.@ 15 FMSHRC at 1463-64. The judge addressed both the issue and the Secretary=s Aonly
reasonable explanation@ language in his decision:

1. The Secretary . . . failed to carry his burden of proving by a preponderance of the
   evidence that an AWC on a cited filter establish[ed] that the mine operator intentionally
   altered the weight of the filter.

2. The Secretary . . . failed to carry his burden of proving by a preponderance of the
   evidence that deliberate conduct on the part of the cited mine operators [was] the only
   reasonable explanation for the cited AWCs.

Id. at 1521. The two-part holding reveals that, first, the judge addressed the issue being tried in
the Common Issues trial, i.e., whether the existence of an AWC established deliberate conduct,
and generally concluded that the Secretary had not shown that it was more likely than not that an
AWC established that a mine operator intentionally tampered with the filter. Second, the judge
addressed the Secretary=s argument that he had proven deliberate conduct was the only reasonable
explanation for AWCs and found that the Secretary had failed to prove such assertion by a
preponderance of the evidence. The Secretary now argues that we should reverse the judge for
addressing the issue being tried and for responding to the Secretary=s argument as set forth in his
posthearing brief.

In arguing that the judge=s reference to the Aonly reasonable explanation@ for AWCs was
reversible error, the Secretary has confused the burden of proof articulated by the judge with his
statement of the central issue to be determined in the Common Issues trial. The issue, as set forth
in the September 1992 Order, was whether the presence of an AWC, by itself, indicated that
tampering had occurred. 14 FMSHRC at 1677. As the judge explained: A[t]he basic issue to be
determined in the common issues trial is whether an AWC on a cited filter establishes per se that

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the mine operator intentionally altered the weight of the filter.@ 15 FMSHRC at 1464 (emphasis
added). We believe the judge appropriately exercised his discretion in setting forth that issue for
determination in the Common Issues trial. Had per se violations been established, mine specific
trials could have been avoided, except as to issues other than the violation, e.g., negligence and
penalty. The determination sought by the Secretary in this review proceeding (that he had shown
by a preponderance of the evidence that it was more likely than not AWCs were the result of
deliberate conduct) would not have obviated the need for mine specific trials on the issue of
whether each particular operator had intentionally altered the weight of a filter and, thus, violated
section 209(b).25 When he determined the issue to be decided in the Common Issues trial, in the
August 1992 Order, the judge was endeavoring to avoid such protracted litigation. See 14
FMSHRC at 1511.

Contrary to the Secretary=s assertion, S. Br. at 31-33, the judge did not require that the
Secretary eliminate all other causes of AWCs. Application of the preponderance standard
necessarily required an examination of the evidence as to other possible causes of AWCs. The
judge weighed the evidence and concluded that the Secretary simply had not shown that it was
more likely than not that an AWC established that a mine operator had engaged in tampering. He
stated: AWeighing the conflicting opinions and considering all the evidence of record, especially
the systematic studies of the experts, I conclude that the evidence does not establish that the
AWCs resulted from deliberate mishandling.@ 15 FMSHRC at 1521.26 The judge found that the

25
In his Motion for Reconsideration of the August 1992 Order, the Secretary
acknowledged as much. He noted that a decision in the Common Issues trial establishing only a
presumption that AWCs are more likely than not the result of deliberate conduct would do little
to advance the litigation. S. Mot. for Recons. at 12.
26
The Secretary complains that the judge erred by failing to assign probability factors to
the possible causes of AWCs. See Oral Arg. Tr. 43-44, 48-49. It was not necessary for the judge
to determine the level of probability for each possible cause. Rather, the Secretary had
responsibility for proving that AWCs resulted from intentional tampering; the judge had only to
decide whether the Secretary succeeded in proving that by a preponderance of the evidence. The
judge determined the Secretary had not.

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Secretary failed to carry his burden of proof, which he correctly characterized as the
preponderance of the evidence standard, because Atoo many other potential causes for the dust
dislodgment patterns on the cited AWCs@ existed. Id. at 1521-22. The judge thus determined
that the Secretary=s evidence did not have such Aconvincing force@ that what he was required to
prove (that AWCs were the result of deliberate tampering) was Amore likely true than not true.@
See, e.g., Merzon v. County of Suffolk, 767 F. Supp. 432, 444-45 (E.D.N.Y. 1991); St. Paul Fire
& Marine Ins. Co. v. United States, 6 F.3d 763,769 (Fed. Cir. 1993); 16 FMSHRC at 896.

The Secretary also argues that, contrary to the judge=s statement, his position early in the
case was that intentional tampering was the most likely, but not necessarily the only, cause of
AWCs. S. Reply Br. at 3 n.3; S. Letter to Comm=n dated April 4, 1995, at 2. Although the judge
referenced the Secretary=s earlier allegations of deliberate conduct as evidenced by the allegations
set forth in the citations, the size of his penalty proposals, his responses to interrogatories, and
Mr. Thaxton=s deposition testimony,27 the judge did not rely on those allegations in determining
that deliberate conduct must be shown in order to prove a violation. Rather, he relied on the plain
language of the regulation. 14 FMSHRC at 1513-16. Thus, irrespective of the Secretary=s
position on whether deliberate conduct need be proven, the judge concluded, based on the plain
language of the regulation, that deliberate conduct was a necessary element in proving a violation
of section 209(b). In view of that determination, the judge appropriately exercised his discretion
in seeking to determine, by way of the Common Issues trial, whether the existence of an AWC, in
itself, established deliberate conduct.

The Secretary did not appeal the judge=s determination that deliberate conduct must be
proven to establish a violation of section 209(b) and, consequently, that determination is not in
issue in this proceeding. 30 U.S.C. ' 823(d)(2)(A)(iii). As noted, he did not seek interlocutory
review, pursuant to the Commission=s Procedural Rules (29 C.F.R. ' 2700.76), of the August
1992 Order or the September 1992 Order, which set forth the central issue and the burden of
proof for the Common Issues trial.

c. Burden of Proof in Keystone Decision

27
We also note the Secretary=s allegation of deliberate tampering set forth in the Special
Assessment Findings issued to all respondents when the penalties were proposed for the contested
violations. See 14 FMSHRC at 1512.

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We disagree with the Secretary=s assertion that the judge erred as to the burden of proof in
the Common Issues trial and that this error Afatally tainted his entire evaluation of the evidence@ in
Keystone. S. Br. at 34. The judge used the phrase, Aonly reasonable explanation,@ in the
Keystone Decision solely in recounting his holdings in the Common Issues Decision. 16
FMSHRC at 861.28 The judge did not require the Secretary to prove that the cited AWCs could
only have resulted from deliberate tampering. Rather, he expressly recognized that the Secretary
bore the burden of proving by a Apreponderance of the evidence that Keystone tampered with the
cited samples.@ Id. at 896. Relying on Concrete Pipe, the judge specifically discussed the
meaning of that term:

The burden of proving by a preponderance of the evidence requires
the party bearing the burden to convince the trier of fact Athat the
existence of a fact is more probable than its nonexistence . . . .@

Id. at 895, quoting 124 L. Ed. 2d at 563. As noted, he also correctly explained that, in order to
preponderate, the evidence must be sufficient to convince a trier of fact that the proposition
asserted is more likely true than not true and that, where the evidence is equally balanced, the
plaintiff has failed to meet his burden. 16 FMSHRC at 895-96, citing Hopkins, 737 F. Supp.
1202; Merzon, 767 F. Supp. 432; Smith v. United States, 557 F. Supp. 42 (W.D. Ark. 1982),
aff=d, 726 F. 2d 428 (8th Cir. 1984). Thus, in Keystone, the judge clearly indicated that he
understood the preponderance standard and correctly construed that standard to mean nothing
more than proof that a proposition is more probable than not. See 16 FMSHRC at 895-96.29

According to the Secretary, the judge=s statement that the Asame evidentiary burden@
applied in both the Keystone and Common Issues trial implies that a standard of proof higher than
preponderance was applied in Keystone. S. Br. at 34-35. In our opinion, the judge=s language
merely indicates that in both cases he applied the preponderance of the evidence standard in
determining whether the Secretary had proven that the AWCs resulted from intentional

28
In Keystone, the judge stated:

On the basis of all the evidence introduced in the common
issues trial, I concluded that the Secretary failed to carry his burden
of proving by a preponderance of the evidence . . . that deliberate
conduct on the part of the cited mine operators is the only
reasonable explanation for the cited AWCs.

16 FMSHRC at 861.
29
We note that the Secretary was in the same position at the commencement of the
Keystone trial as he would have been had the judge not consolidated the Dust Cases and held the
Common Issues trial. He was required to prove, by a preponderance of the evidence, that
Keystone=s AWCs were caused by deliberate tampering.

30

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Page 31

tampering. Except where he repeated his conclusions from the Common Issues Decision, the
judge did not incorporate into Keystone the language articulating the issue disposed of in the
Common Issues Decision, i.e., whether an AWC establishes that an operator intentionally altered
the weight of the filter. See 16 FMSHRC at 861; 15 FMSHRC at 1464, 1521. References by the
judge in the Common Issues Decision to Aonly reasonable explanation@ addressed the issue before
him and the Secretary=s argument, and were not a departure from the preponderance of evidence
standard. We conclude that the judge correctly applied the preponderance standard in Keystone.

In sum, we conclude that the judge correctly applied the preponderance of the evidence
standard in both the Common Issues and Keystone Decisions.

C. Scientific Issues

1. Introduction

The judge considered the entire record before him in making factual findings and in
reaching conclusions in his Common Issues Decision and in his Keystone Decision. 15 FMSHRC
at 1456, 1521; 16 FMSHRC at 903. Many of his findings were drawn from the reports and
testimony of credited experts. On review the Secretary raises a number of issues concerning the
judge=s admission and crediting of the scientific evidence presented by the expert witnesses to
explain the causes of AWCs. Specifically, the Secretary contends that the judge erred in failing to
credit Mr. Thaxton=s and Dr. Marple=s opinions that the appearances of AWCs were consistent
with blowing air into the filters; in crediting Dr. Lee=s opinion that AWCs were consistent with
accidental impacts; in admitting and relying on Dr. Corn=s opinion that accidental events were the
likely cause of AWCs; in analyzing evidence of filter manufacturing variables; and in admitting
and crediting Dr. Lee=s testimony on the effect of water sprays and scrubber systems on the
susceptibility of AWC formation. PDR Issues 2, 3, 4, 5, 9, 10, and 11.

In considering the issues raised by the Secretary=s petition, we are guided by principles
established under Rule 702 of the Federal Rules of Evidence: AIf scientific, technical, or other
specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact
in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education,
may testify thereto in the form of an opinion or otherwise.@ Fed. R. Evid. ' 702. AExpert
witnesses testify to offer their scientific opinions on technical matters to the trier of fact.@ Cyprus
Tonopah Mining Corp., 15 FMSHRC 367, 372 (March 1993), quoting Asarco, Inc., 14
FMSHRC 941, 949 (June 1992). AUnlike an ordinary witness, . . . an expert is permitted wide
latitude to offer opinions, including those that are not based on first-hand knowledge or
observation.@ Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. __ , 113 S. Ct. 2786, 125
L. Ed. 2d 469, 482 (1993).

All the witnesses who testified in technical or scientific areas were accepted by the judge
as experts in their respective fields. The qualification of experts and the admission of their
testimony are matters within the discretion of the trial judge. Coleman v. Parkline Corp., 844

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F.2d 863, 866 (D.C. Cir. 1988); Polk v. Ford Motor Co., 529 F.2d 259, 271 (8th Cir. 1976), cert.
denied, 426 U.S. 907 (1976). AIn the absence of clear error, as a matter of law, the trial judge=s
decision [as to a witness=s qualification to express an opinion] will not be reversed.@ Payton v.
Abbott Labs, 780 F.2d 147, 155 (1st Cir. 1985), quoting A. Belanger & Sons, Inc. v. United
States, 275 F.2d 372, 376 (1st Cir. 1960). Under an abuse of discretion standard, Aa trial court=s
decision [to admit expert witness testimony] will not be disturbed unless the appellate court has a
definite and firm conviction that the lower court made a clear error of judgment or exceeded the
bounds of permissible choice in the circumstances.@ Post Office v. Portec, Inc., 913 F.2d 802,
807 (10th Cir. 1990), quoting United States v. Ortiz, 804 F.2d 1161, 1164 n.2 (10th Cir. 1986).

A[T]he resolution of conflicting testimony, including that of expert witnesses, is for the
trier of fact.@ Jackson v. Hartford Accident and Indemnity Co., 422 F.2d 1272, 1275 (8th Cir.
1970) (citation omitted). If the opinions of expert witnesses in a proceeding conflict, the judge
must determine which opinion to credit, based on such factors as the credentials of the expert and
the scientific bases for the expert=s opinion. Cyprus Tonopah, 15 FMSHRC at 372 (citation
omitted). A[A] trial judge must ensure that . . . scientific testimony or evidence admitted is not
only relevant, but reliable.@ Daubert, 125 L. Ed. 2d at 480. Further, the bias of an expert witness
is a proper matter for the judge to consider in determining the weight to be given the expert=s
opinion. See United States v. Cutler, 58 F.3d 825, 836 (2d Cir. 1995). A[A]n ALJ has substantial
latitude in choosing between conflicting expert testimony.@ L & J Energy Co. v. Secretary of
Labor, 57 F.3d 1086, 1088 (D.C. Cir. 1995); accord Cyprus Tonopah, 15 FMSHRC at 373. The
judge=s decision to credit the opinion of one expert over the opinion of another expert is
reviewable under an abuse of discretion standard. Chapman v. United States, 169 F.2d 641, 645
(9th Cir. 1948), cert. denied, 335 U.S. 860 (1948) (citations omitted); see also Autoskill, Inc. v.
National Educ. Support Sys., 994 F.2d 1476, 1493 (10th Cir. 1993); An-Son Corp. v. Holland-
America Ins. Co., 767 F.2d 700, 702-03 (10th Cir. 1985) (when Aevidence consisted primarily of
a >battle of experts,=@ resolution was the appropriate province of the trial court and appellate court
was Aloath to disturb@ a finding based on such a resolution). Accord Cyprus Tonopah, 15
FMSHRC at 373.

In reviewing a judge=s factual determinations drawn from credited testimony, including
expert testimony, the Commission is bound by the terms of the Mine Act to apply the substantial
evidence test. See 30 U.S.C. ' 823(d)(2)(A)(ii)(I). The term Asubstantial evidence@ means Asuch
relevant evidence as a reasonable mind might accept as adequate to support [the judge=s]
conclusion.@ Rochester & Pittsburgh Coal Co., 11 FMSHRC 2159, 2163 (November 1989),
quoting Consolidated Edison Co. v. NLRB, 305 U.S. 197, 229 (1938). A[If an] ALJ provide[s] an
explanation . . . for disregarding [other evidence], the expert testimony alone could have
constituted substantial evidence in support of the conclusion.@ L & J Energy, 57 F.3d at 1088.

2. Judge=s Rejection of Mr. Thaxton=s Opinion on AWC Causation30

30
This section addresses Issue No. 2 in the PDR.

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The judge concluded that Urling=s AWCs did not result from normal sampling; something
happened in the mine or thereafter to cause the abnormal appearances. 16 FMSHRC at 897. He
found Thaxton=s conclusions that the cause was intentional tampering Ato a considerable extent
subjective.@ He noted that Thaxton=s testing was unscientific and that his distinction between
cited and no-call filters was Atenuous at best.@ The judge was Anot able to conclude on the basis
of Thaxton=s reports and testimony that the abnormal appearances on the Urling filters were
caused by intentional tampering.@ Id.

In his PDR, the Secretary asserts that the judge erred in failing to credit the findings of
Mr. Thaxton and Dr. Marple31 that Athe appearances of cited AWC filters at Urling were more
consistent with appearances generated . . . by deliberately blowing reverse air . . . than by
appearances generated by simulated accidental events.@ PDR at 12. In support, the Secretary
argues that the judge=s rejection of Thaxton=s opinion as to the cause of AWCs was based, in
critical part, on his no-call findings. Id.; S. Br. at 55. He takes issue with the judge=s
determination that Thaxton=s reasons for citing no-call filters were Atenuous at best@ and not Aan
appropriate exercise of agency discretion.@ S. Br. at 55-56. The Secretary contends that the no-
call designation was a reasonable way of handling a few questionable filters and that a decision
not to cite those filters was a reasonable exercise of MSHA=s discretion. Id. at 59. Keystone
counters that the judge rejected Thaxton=s testimony in large part because of his failure to provide
a scientific basis for his conclusions and because of his bias. K. Br. at 64-69. According to
Keystone, the judge=s rejection of Thaxton=s opinion was justified by the record. Id. at 64, 69,
112-18.

The judge did not err in declining to conclude, based on Thaxton=s opinion, that
intentional tampering caused AWCs. He found Thaxton=s testing to be subjective and non-
systematic, and not conducted with any scientific rigor. 16 FMSHRC at 897; 15 FMSHRC at
1473. The judge noted, in comparing Thaxton=s background to the Aimpressive credentials@ of
Lee and Marple, that Thaxton Ais not a scientist . . . .@ 16 FMSHRC at 898. Thaxton did not use
written criteria to distinguish normal filters from those he considered abnormal, Tr. 133, nor did
he prepare a Acomprehensive written protocol based on scientific testing relating specific
appearances to different kinds of tampering.@ 16 FMSHRC at 897. None of his tests were based
on a written protocol. Tr. 123. No written report of his 1983 or 1989 tests was introduced into
evidence.32 He did not recall the number of filter cassettes he had tested in 1983, but estimated
31
The Secretary has offered no support in his briefs for his assertion that the judge erred
in failing to credit Dr. Marple=s opinion. Consequently, we do not address it. ASARCO Mining
Co., 15 FMSHRC 1303, 1304 n.3 (July 1993).
32
Thaxton kept inadequate records of his tests. He maintained no data on the 1983
testing other than one page containing eight to ten of the actual filters with the weight recorded
before and after application of reverse air flow. Tr. 110, 118-19. At trial, Thaxton was
questioned regarding photographs of some test filters he created in 1991, but he was unable to
identify the specific mechanism that caused the filter appearances in the photographs because he
kept no records of that testing. Tr. 109-10, 120-22.

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that Abetween 25 to 50 filters . . . were played with to see how they would behave.@ Tr. 110. Nor
did Thaxton subject the 1983 test filters to impact forces in an attempt to determine the potential
for dust dislodgment patterns as a result of accidental events. Tr. 119, 123. Thaxton kept no
records as to the particulars of his examinations, such as whether he reviewed the filters from the
reverse side or with a magnifying glass. Tr. 619-21. He failed to note the characteristics that
initially caused him to cite a particular filter. Tr. 611, 628; see also Tr. 619-21. We conclude that
the judge did not abuse his discretion in determining, on the basis of this evidence, that Thaxton=s
opinion on the causes of AWCs was not sufficiently grounded in reliable scientific evidence to
support a conclusion of deliberate tampering. A[A] trial judge must ensure that . . . scientific
testimony or evidence admitted is not only relevant, but reliable.@ Daubert, 125 L. Ed. 2d at 480;
Cyprus Tonopah, 15 FMSHRC at 372 (in evaluating an expert=s opinion, a judge may properly
focus on the scientific basis for that opinion).

The Secretary asserts that the judge erred in discounting Thaxton=s testimony based on a
lack of distinction between cited and no-call filters.33 Denying that the similarity between cited
and no-call filters was the result of inconsistency on MSHA=s part, the Secretary claims
prosecutorial discretion and points to evidence of other factors that sometimes determined
Thaxton=s decision on whether filters should be cited. S. Br. at 56-60. The Secretary states that
Thaxton considered whether the same operator had submitted other filters with AWCs and
whether those filters were submitted at or near the time of other AWC submissions. K. Tr. 1174-

76. Thus, if a questionable filter was the only unusual filter submitted by an operator, Thaxton
    was not likely to cite it. K. Tr. 1172-73. On the other hand, a questionable filter was cited if
    similar filters had been submitted by that operator within a short time period. K. Tr. 1174-76. If
    a questionable filter was submitted by an operator who had submitted a number of filters with
    AWCs, Thaxton considered that filter to demonstrate tampering. K. Tr. 917-18. Thus, it appears
    that, in evaluating marginal patterns of dust dislodgment, Thaxton=s reliance on an operator=s
    other filters exaggerated differences in citation rates between operators and differences in citation
    rates over time. Thaxton=s procedure provides further evidence that the judge was well within his
    discretion in finding Thaxton=s determinations to be non-systematic and lacking in scientific rigor
    and in discounting Thaxton=s opinion as to the causes of AWCs.

The judge, in determining that Thaxton=s testimony was not sufficiently objective to
support a determination to cite an operator with deliberate conduct, also referenced
Thaxton=s own testimony that: A[t]he no-call filters do not exhibit th[e] degree of dust removal
that I would feel comfortable . . . saying that there is a citation to be issued.@ Tr. 139; 15
FMSHRC at 1466; 16 FMSHRC at 897. This testimony reveals both the imprecision and
subjectivity in Thaxton=s determinations and provides support for the judge=s decision to give
diminished weight to his opinion testimony as to the causes of AWCs. As noted by the judge,

33
Dr. Lee testified that many of the Urling filters were indistinguishable from no-calls. 16
FMSHRC at 876; K. Ex. 2001, at 3. The judge himself observed filters at issue in both the
Common Issues and Keystone trials. 15 FMSHRC at 1468; 16 FMSHRC at 869.

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decisions to charge operators with deliberate tampering must be based on Amore objective
standards.@ 16 FMSHRC at 897.

The judge also gave diminished weight to Thaxton=s determination as to causation of
AWCs because Ahe was not a disinterested witness.@ Id. at 872; 15 FMSHRC at 1473. He had
been employed by MSHA for 16 years as an industrial hygienist. 15 FMSHRC at 1473; Gov=t Ex.

344. Thaxton determined the issuance of each citation. 16 FMSHRC at 859. We conclude that,
     in evaluating Thaxton=s testimony, the judge properly considered the fact that Thaxton was not
     disinterested. The bias of an expert witness is a proper matter for a court to consider in weighing
     the expert=s opinion. See Cutler, 58 F.3d at 836.

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We conclude that the judge did not abuse his discretion in determining that Thaxton=s
opinion was not sufficiently grounded in reliable scientific evidence nor sufficiently objective and
disinterested to support a determination of deliberate tampering.

3. Judge=s Crediting of Dr. Lee=s Opinion on AWC Causation34

In his Common Issues Decision, the judge found that AWCs could have resulted from
intentional acts. 15 FMSHRC at 1513. Crediting the opinion testimony of Dr. Lee and other
operator experts, he also found that AWCs could have resulted from accidental and incidental
impacts to the cassette and hose. Id. at 1513-14. He found that many of the filters subjected to
impact tests exhibited dust dislodgment patterns indistinguishable from cited filters. Id. at 1514.

In his Keystone Decision, the judge concluded that 73 of the 75 cited filters resulted in
whole or in part from reverse air flow, but that the forces involved were Agenerally less than those
created by deliberate blowing through the filter cassette.@ 16 FMSHRC at 900. He found that
none of the Urling filters exhibited cones and that this indicated only slight impact forces had
created the dislodgments. Id. at 899-900. The judge further concluded that the Adust
dislodgment patterns may have been influenced by impacts to the cassettes or sampling assemblies
as well as reverse air though the cassettes,@ as described in Dr. Lee=s mixed-mode theory. Id. at
900.

In his PDR, the Secretary contends that the judge erred in crediting and relying on Lee=s
opinion that AWCs were consistent with accidental impacts rather than intentional blowing
through filter cassettes. PDR at 12-13. In support, he argues that the relative degrees of force
involved in intentional blowing and accidental impacts had not been measured, that Lee=s opinion
on his Aconing theory@ in the Keystone trial was inconsistent with his opinion in the Common
Issues trial, that his classification system was unreliable, and that the judge erred in crediting Lee=s
opinion on causation of AWCs while rejecting his opinion on MSHA handling. Id. at 13-14. The
Secretary further argues that Lee=s mixed-mode theory, advanced in Keystone, was unreliable and
that the judge erred in failing to provide adequate reason for crediting Lee=s opinions. S. Br. at
64-75.

In support of his position that the judge erred in crediting Lee=s opinion that AWCs were
consistent with accidentally caused impacts, the Secretary argues that Dr. Marple=s testimony
provided clear evidence that the cited AWCs were consistent with intentional tampering and
inconsistent with accidental forces. S. Br. at 60. He points to Dr. Marple=s testimony that his
experiments simulating accidental events produced few AWCs. Id. at 60 n.22.

34
This section addresses Issue No. 3 in the PDR.

36

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Page 37

Keystone counters that the record fully supports the judge=s conclusions that the
dislodgment patterns on Urling filters may have been caused by impacts to the hoses, causing
reverse air pulses, as well as impacts to the cyclones, causing mechanical pulses, as set forth in
Lee=s mixed-mode theory, and that these forces, which were weaker than those caused by
deliberate blowing, resulted in the absence of cones on Urling filters and in dislodgment patterns
that were often larger and more diffuse than those caused by deliberate blowing. K. Br. at 74-79,
82-86.

Dr. Lee has a doctorate in solid state physics and is president and chief scientist of the
R. J. Lee Group, which had performed testing and research studies for numerous government
agencies and for private industry. 15 FMSHRC at 1470; Tr. 5923-48, 5935; R. Ex. 1001A. He
was accepted as an expert witness in physics, materials characterization and analysis, and
environmental monitoring. 15 FMSHRC at 1488. His opinion that AWCs could be caused by
accidental means was based on his Common Issues experiments, in which he generated more than
3,100 dust samples in the R. J. Lee Group dust tunnel, using coal from various seams and
particles of similar size, shape, and aerodynamic diameter as found in coal mines. Id. at 1489.
His samples were collected under controlled temperature and humidity. Id. He also obtained
more than 650 samples from mines across the country. Id. He then conducted a series of tests
involving impacts to the cyclones and hoses of dust sampling units, which produced filters with
AWCs. Id.; R. Ex. 1001, at 11-13, R. Ex. 1002; see Tr. 6315-51. In addition to his reports and
testimony, Lee showed a videotape recording of three incidents of a pump being dropped on a
hose, two of which resulted in AWCs on the cassette filter. R. Ex. 1006. In the Keystone
proceeding, Lee refined his experiments and performed 55 tests in which carrying boxes were
dropped on sampling unit hoses; 40 AWC appearances, similar to those of the Urling filters,
resulted. K. Ex. 2002.

Lee=s opinion as to accidental causation of AWCs was also corroborated by other experts,
Dr. McFarland and Dr. Grayson, who testified that they had produced AWCs through impacts.
(McFarland) Tr. 4759-60, 4915, 5199-5200; (Grayson) R. Ex. 1014, at 16; Tr. 5551. McFarland
conducted a courtroom demonstration in which a 31-pound tool box was twice dropped on the
hose of a sampling assembly and twice resulted in AWCs. 15 FMSHRC at 1503; Tr. 4877-80,
4887-88, 4891, 5187-90.

Moreover, the record shows that Dr. Marple, the Secretary=s expert, came to realize that
impacts to hoses could result in AWCs. His first report, Gov=t Ex. 280, failed to address the
effects of hose impacts or the effect of filter-to-foil distance on susceptibility to AWCs and he
performed further studies only after he learned of these phenomena from the operators= experts.
Tr. 2277, 2282. After performing hose impact tests, Marple retracted the conclusion set forth in
his first report that AWCs Acould only occur by an intentional act.@ Gov=t Ex. 280, at 7. In his
supplemental report, Marple concluded that Aextreme mishandling@ could cause AWCs.35 Gov=t
35
The changing nature of Marple=s opinions diminishes their weight. See, e.g.,
Kenbrooke Fabrics, Inc. v. Holland Fabrics, Inc., 602 F. Supp. 151, 154 (S.D. N.Y. 1984).

37

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Ex. 282, at 14. Compare Gov=t Ex. 280 with Gov=t Ex. 282. Marple was able to replicate AWCs
by forcefully stepping on hoses. Tr. 2354-56; Gov=t Ex. 282, at 6-7; see also Gov=t Ex. 311. The
Secretary, in his Reply Brief to the Commission, concedes: A[A]s evidence was developed during
the course of discovery, the Secretary=s understanding of AWC formation also developed.@ S.
Reply Br. at 3 n.3.

Similarly, Mr. Thaxton reviewed Lee=s experimental filters and determined that 105 had
AWCs.36 Tr. 439, 445. Of those 105 filters, 40 had been formed by cassette drop, cyclone drop,
hose impact, hose tread, or hose wrap -- each a type of forceful contact. See Gov=t Ex. 267,
Attach. 2; Tr. 7062-63. See also Tr. 577-78. Thaxton=s testimony that 40 impact-caused AWCs
were citable also corroborates the evidence that accidental events could have caused the AWCs.

Thus, we conclude that the judge did not err in choosing to credit Lee=s opinion over
Marple=s to the contrary.

The Secretary also contends that Lee=s testimony on coning in Keystone was inconsistent
with his testimony in the Common Issues trial. S. Br. at 61.37 In the Common Issues proceeding,
Lee stated that coning is not necessarily associated with AWCs, R. Ex. 1003, at 2; Tr. 6418-37,
and that deliberate reverse air flow is not necessary for the creation of cones. R. Ex. 1003, at 5.
Lee noted that cones were present on the MSHA inspectors= sample filters. Id. In Keystone, he
stated that Aair blowing through filters using reverse air has a tendency to generate cones,@ K. Tr.
3879; K. Ex. 2001, at 7, and that, as a general proposition, deliberate reverse air flow involves
more force than accidental events. K. Tr. 3988. Lee concluded that the slight dust dislodgment
on many of the Urling filters indicated causation by a much smaller force than that generated by
deliberate reverse air. K. Ex. 2001, at 5; see also 16 FMSHRC at 899. We find no discrepancy
between Lee=s testimony in the Common Issues trial and his testimony in Keystone. In fact, Lee=s
report in Keystone expressly harmonizes his conclusions with respect to the Urling filters with his
general observations in the Common Issues trial: AResults by all experts indicate that physically
blowing through the outlet creates a high percentage of cones although some dimples and cones
are observed under other conditions.@ K. Ex. 2001, at 7. Moreover, Thaxton corroborated Lee=s
view by acknowledging in both trials that cones indicated very forceful application of reverse air
to the filters. Tr. 209, 1258; K. Tr. 908, 1072. Thaxton testified that R&P filters had only slight
cones or dimples as compared to those of some other mines, in which 50 to 60% of the cited
filters had cones.38 K. Tr. 1072-73.

36
Thaxton did not review Lee=s 3,877 filters under scientific, double-blind conditions and,
therefore, knew that he was reviewing filters of the operators= expert. Gov=t Ex. 267, at 4-6; Oral
Arg. Tr. 46.
37
The Secretary=s Brief refers to Lee=s Coning Report as R. Ex. A1002"; that report was
admitted as R. Ex. A1003.@ Tr. 5996.
38
Although, in 1992, Thaxton had classified seven Urling filters as having cones, a year
later he determined that none of the filters had cones and only one or two had dimples. K. Gov=t

38

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Page 39

Ex. 505. Thaxton believed that cones relaxed with time. His belief was based not on systematic
experimentation but on his knowledge that filters are composed of a plastic material and plastics
flatten out with time, as well as on his observation of one coned filter. K. Tr. 888-891. Lee, in
his observations of numerous experimental filters, found no evidence that cones relaxed or
flattened over time. K. Tr. 3883.

39

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Page 40

Consequently, we reject the Secretary=s contention that Lee=s testimony on coning was
inconsistent.

The Secretary further contends that the judge erred in accepting Lee=s opinion as to
accidental AWC causation while rejecting his opinion that MSHA=s handling of sample filters was
one cause of AWCs. PDR at 13-14; S. Br. at 74, citing Ona Corp. v. NLRB, 729 F.2d 713, 719
(11th Cir. 1984) (AALJ=s credibility finding will be disregarded if . . . inherently unreasonable or
self-contradictory@). We conclude that it was not unreasonable or contradictory for the judge to
accept Lee=s opinion as to AWC formation in general, which was based on scientific experiments,
while rejecting other, less compelling, aspects of his opinion. See DeSarno v. Department of
Commerce, 761 F.2d 657, 661 (Fed. Cir. 1985); Hathaway v. Merit Systems Protection Bd., 981
F.2d 1237, 1241 (Fed. Cir. 1992). In our view, the judge closely examined Lee=s opinion,
including its underlying basis, and properly chose to credit those aspects that he found persuasive.
The judge similarly credited certain aspects of Thaxton=s opinion, concerning the classification of
filters, 15 FMSHRC at 1469, while rejecting other aspects, concerning causation. Id. at 1473-74,
1513, 1518, 1521.

The Secretary also asserts that the judge erred in accepting Lee=s opinion as to causation
because his AWC classification system was unreliable. PDR at 13; S. Br. at 61-64. The judge
recognized that Lee=s classification system was not applied without error. 15 FMSHRC at 1489.
Lee=s inconsistency, however, in categorizing filter appearances does not substantially detract
from his conclusion, drawn from his experiments, that accidental impacts to sampling equipment
can cause AWCs.

The Secretary also challenges, on the basis that the theory lacks scientific support, S. Br.
at 69, the judge=s crediting of Lee=s mixed-mode theory, in which he attributed the appearance of
the Urling filters, which differed from those blown through deliberately, to a combination of
events involving both impacts to the hose (causing reverse air pulses) and impacts to the cyclone
(causing mechanical pulses). K. Ex. 2001, at 18; K. Tr. 3849-50, 3864-65, 3867-68.39 That
theory is supported by Lee=s experiments, involving mixed-mode events, by Marple=s testimony
and videotape, Gov=t. Ex. 286, and by Marple and Rubow=s dust dislodgment studies. As noted,
Lee performed 55 tests of box drops that resulted in 40 filters with AWCs similar to those on the
Urling filters. K. Tr. 3846; K. Ex. 2002, at 3. (Of the remaining 15 filters, Lee opined that eleven
had no dust dislodgment pattern and four had dislodgment patterns that were dissimilar to the
Urling filters. K. Ex. 2002, at 3.) For his tests, Lee employed the actual carrying boxes used by
R&P and dropped them or firmly placed them down on hoses. K. Tr. 3833-36, 3843; K. Ex.
39
We note that Marple testified to the contrary, that mixed-mode events failed to cause
filter appearances similar to those on the cited filters. K. Tr. 1472-81. Although Marple=s tests of
40 mixed-mode events, performed by subjecting dust sampling units to rough transportation in
trucks and tractors, resulted in only one AWC, K. Gov=t Ex. 509; K. Tr. 1509, Marple=s tests
were criticized by Lee because he failed to adequately compress the hoses under the carrying box.
K. Tr. 3848-49; K. Gov=t Ex. 509, at 3-4.

40

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Page 41

2002. Lee=s theory was also based in part on his Common Issues experimental filters and on
      Marple=s videotape of AWC formation, Gov=t Ex. 286, shown at the Common Issues trial. K. Tr.
      3817, 3871, 3915-16.

Dr. Lee concluded that most of the cited filters showed comparatively little dust
dislodgment and had slightly larger dislodgment areas than AWCs created by deliberate blowing.
16 FMSHRC at 899. The Secretary criticizes Lee=s mixed-mode theory in part by arguing that
the Urling filters do not have large and diffuse patterns of dislodgment. S. Br. at 71. The
Secretary recognizes, however, that the diameters of the dislodgment area of the Urling filters
were somewhat larger than those of experimental filters subjected to deliberate blowing. S. Br. at

68. Marple acknowledged that the dislodgment areas of the Urling filters were, in fact, larger
    than those of his experimental filters created by deliberate blowing. K. Tr. 1468; K. Gov=t Ex.
    508, at 13, 16. Marple as well as Lee found that the Urling filters had dislodgments with
    diameters larger than 6 mm. K. Tr. 1468, 3849; K. Ex. 2002A; K. Gov=t Ex. 508. Marple stated
    his belief that the larger diameters resulted from deterioration as the filters aged, but he presented
    no scientific research to support that view. K. Tr. 1468-69. Lee concluded that the larger
    diameters showed that the filters were subjected to mechanical pulses due to impacts because, in
    his experiments, such impacts caused larger dislodgment areas. K. Tr. 3849-50, 3856-58, 3863-
    65, 3911-18; K. Ex. 2002A. Marple acknowledged and his videotape showed that impacts to
    cassettes result in dislodgments with a Awider, more diffuse ring,@ whereas reverse air flow caused
    sharply defined 6 mm circular dislodgments. Tr. 2111-16, referencing Gov=t Ex. 280, at 35; see
    also Gov=t Ex. 280, at 36. Lee relied on this videotape to explain his theory that the Urling filters,
    which had dislodgment both inside and outside the 6 mm central area, exhibited characteristics of
    both reverse air and mechanical pulses. K. Tr. 3817, 3870-71. Lee=s theory is further supported
    by Marple and Rubow=s systematic dust dislodgment studies, in which 210 filter cassettes
    subjected to three to six-foot drops resulted in a dislodgment pattern different from that resulting
    from reverse air, Ait was larger in diameter and less sharply defined.@ 15 FMSHRC at 1476-77.

Consequently, we reject the Secretary=s assertion that the mixed-mode theory lacks
scientific support.

The Secretary also complains that Lee=s mixed-mode theory was not developed until after
the Common Issues trial. S. Br. at 71-72. We do not find it inappropriate that Lee conducted
further research and produced a second report to address more specifically the particular
characteristics of the filters cited in the Keystone case.

We also reject the Secretary=s assertion that the judge failed to discuss the comparable
strengths and weaknesses of the opinions of Lee, Marple, and Thaxton or explain his reasons for
crediting Lee. In the Common Issues Decision, as well as in the Keystone Decision, the judge
described the scientific testimony in detail and carefully explained the basis for crediting Lee=s
testimony. See 15 FMSHRC at 1473-84, 1488-96, 1513-18, 1521-22; 16 FMSHRC at 872-878,
898-900.

41

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Page 42

A[A]n [administrative law judge] has substantial latitude in choosing between conflicting
expert testimony.@ L&J Energy, 57 F.3d at 1088. Lee=s opinions had a scientific basis and the
judge was within his discretion in crediting it. We emphasize that, in evaluating Lee=s testimony,
the judge himself observed Urling filters. 16 FMSHRC at 869. We conclude that the judge did
not abuse his discretion in crediting Lee=s testimony that AWCs were consistent with accidental
impacts over Marple=s testimony that they were not.

4. Judge=s Admission of and Reliance on Dr. Corn=s Opinions40

The judge credited the opinion of Dr. Corn, along with that of Dr. Lee, Dr. Grayson, and
Dr. McFarland, in determining that a filter cassette with a shorter filter-to-foil distance is more
prone to dust dislodgment than one with a greater distance. 15 FMSHRC at 1515. The judge
also credited Dr. Corn=s opinion that size and shape of the dust particles could be a factor in dust
dislodgment patterns. Id. at 1517.

40
This section addresses Issues No. 4 and 5 in the PDR.

42

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Page 43

In his PDR, the Secretary asserts that the judge erred in admitting and relying on Corn=s
testimony to corroborate Lee=s opinion that accidental impacts cause AWCs.41 PDR at 14. The
Secretary argues that the judge erred in admitting portions of Corn=s opinion at trial42 and that the
testimony lacked a scientific foundation. S. Br. at 75-78. The Secretary relies on Rule
26(b)(4)(A), (e)(1), & (e)(2) of the Federal Rules of Civil Procedure, which provides that
discovery may be obtained of facts known and opinions held by experts and that a party has a duty
to supplement its disclosure of information provided by experts.43 Intervenors counter that the
judge=s admission of and reliance on Corn=s testimony was within his discretion, was reasonable
given Corn=s background and credentials, and was justified because Corn=s opinions were
supported by the evidence. I. Br. at 72-77.

Corn=s report, disclosed during discovery, states: A[W]e reviewed data generated by the
R.J. Lee Group as a result of their experiments. We agree with their conclusions regarding filter
cassette susceptibility to [AWC] formation . . . (e.g., >filters-to-foil= distance) . . . .@ R. Ex. 1037,
at 7. At the Common Issues trial, the Secretary objected to the questioning of Corn about Lee=s
work, on the grounds that portions of his opinion had not been disclosed during discovery. Tr.
7551-52. The judge overruled the objection because, at the pretrial conference, he had ruled that,
at trial, Aexpert witnesses . . . should be able to respond to criticism by other experts@ and he
considered Corn=s testimony to be a response to Dr. Marple=s criticism of Dr. Lee. Tr. 7573; Tr.
23-24 (Prehr=g Conf. Nov. 17, 1992). We conclude that, under Rule 26(a)(2)(B),44 the judge

41
The Secretary, in his brief, asserts generally that A[t]he judge used Dr. Corn=s testimony
to corroborate Dr. Lee=s opinion that accidental causes account for AWC patterns,@ but he
provides no supporting citation. S. Br. at 75. In our opinion, the judge did not credit Corn in
areas other than the effect of filter-to-foil distance and dust particle size and shape. See 15
FMSHRC at 1512-13, 1515, 1517.
42
Apparently, the Secretary=s objection to the admission of Corn=s testimony does not
extend to his testimony on filter-to-foil distances. At trial, in support of his objection, the
Secretary acknowledged that Corn=s report, disclosed during discovery, contained the statement
that Ahe agreed with Dr. Lee on filter-to-foil distance . . . .@ Tr. 7551-52.
43
Commission Procedural Rule 1(b), 29 C.F.R. ' 2700.1(b), incorporates the Federal
Rules of Civil Procedure, so far as practicable, on any procedural question not regulated by the
Mine Act, the Commission=s Procedural Rules, or the Administrative Procedure Act, 5 U.S.C.
' 500 et seq.
44
Rule 26(a)(2)(B) provides:

Except as otherwise stipulated or directed by the court, . . .
[t]he [expert] report shall contain a complete statement of
all opinions to be expressed and the basis and reasons
therefor; the data or other information considered by the
witness in forming the opinions . . . .

43

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Page 44

properly admitted Corn=s expert report because he had Aotherwise . . . directed@ in a pretrial ruling
that experts would be allowed at trial to respond to other experts= opinions.

Fed. R. Civ. P. 26(a)(2)(B) (emphasis added).

44

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Page 45

Further, a judge=s determination of a duty to supplement discovery under Rule 26(e) and
the exclusion of trial testimony are committed to his sound discretion. Phil Crowley Steel Corp.
v. Macomber, Inc., 601 F.2d 342, 344 (8th Cir. 1979).45 A judge=s decision to allow such
evidence will usually not be disturbed unless it results in undue prejudice or fundamental
unfairness. Id. The Secretary was not prejudiced by Corn=s testimony. Corn had been deposed
by the Secretary concerning his work with Lee. Tr. 7552. Further, Corn=s report, disclosed
during discovery, stated that he had reviewed the experimental data of the R. J. Lee Group and
that he agreed with their conclusions regarding filter susceptibility to AWC formation. We find
no abuse of the judge=s discretion in his admission of Corn's testimony.

The Secretary specifically disputes the scientific foundation for Corn=s opinions that: (1) a
filter cassette with a smaller filter-to-foil distance was more prone to dust dislodgment than a filter
with a larger filter-to-foil distance; and (2) the size and shape of dust particles could be a factor in
dislodgment patterns. S. Br. at 75. We conclude that these two opinions were within Corn=s area
of expertise.46 Corn has a doctorate in industrial hygiene and sanitary engineering and is professor
in, and division director of, the Department of Environmental Health Services, School of Hygiene
and Public Health at Johns Hopkins University. 15 FMSHRC at 1496. He was accepted as an
expert witness in the fields of aerosol and particle physics, including the adhesion and dislodgment
of particles, coal mine dust sampling technology, and federal occupational safety and health
regulation and enforcement systems. Tr. 7490; see also 15 FMSHRC at 1496-97. Corn studied
the adhesion forces of particles and concluded, based on his review of the scientific literature and
information received from Lee, that Lee=s dust particles were representative of dust in mines. Tr.
7553-55, 7570-71, 8025-26. Thus, Corn=s testimony had a proper scientific foundation. In
addition, Corn was directly involved with the measurements and tests on which he based his
opinion. Corn visited Lee=s research facility on a number of occasions and reviewed Lee=s
equipment, protocols, and procedures. Tr. 7560, 7581-83, 7585, 8009, 8085-86. Corn himself

45
In support of the proposition that Corn=s testimony should have been excluded, the
Secretary relies on Freund v. Fleetwood Enterprises, Inc., 956 F.2d 354, 356-59 (1st Cir. 1992);
Jenkins v. Whittaker Corp., 785 F.2d 720, 728 (9th Cir. 1986), cert. denied, 479 U.S. 918
(1986); and Jefferson v. Davis, 131 F.R.D. 522, 528 (N.D. Ill. 1990). S. Br. at 77. These cases
emphasize the trial judge=s discretion in discovery-related matters. For example, Freund, which
involved the exclusion of expert testimony at trial, states that the judge=s discretion is not to be
disturbed absent manifest error. 956 F.2d at 356-59.
46
The judge did not accept Corn as an expert in, nor rely on his conclusions as to, image
analysis. 15 FMSHRC at 1509-13. There is no inherent contradiction in a judge=s accepting an
expert=s testimony in areas in which he is well qualified and rejecting his testimony in areas in
which he is less qualified. Cf. Wilkinson v. Rosenthal & Co., 712 F. Supp. 474, 478 (E.D. Pa.
1989) (expert qualified to testify in areas in which he had appropriate education and experience
but was not qualified to testify in areas in which he lacked education or experience); Bass v. Spitz,
522 F. Supp. 1343, 1352-53 (E.D. Mich. 1981) (economist could not testify in areas beyond his
knowledge and expertise).

45

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Page 46

measured filter-to-foil distances of cassettes and also examined 1,248 of the cited filters.47 Tr.
7562, 7591; R. Ex. 1037, at 2. Corn requested that Lee examine the size of the airborne dust
particles used in his dust tunnel experiments. Tr. 7570-71. We conclude that the Secretary has
not demonstrated that the judge abused his discretion in crediting Dr. Corn=s testimony.

47
Corn=s opinion that a shorter filter-to-foil distance makes a filter more prone to dust
dislodgment was one of several expert opinions to that effect. See 15 FMSHRC at 1515. Thus,
even if Corn=s opinion had not been properly credited by the judge, other record evidence
supports the judge=s findings on filter-to-foil distance.

46

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Page 47

5. Filter-to-foil Distance and Other Manufacturing Variables48

The judge determined that the distance between the filter and the aluminum foil cone of
dust sampling cassettes was variable and that casettes with shorter filter-to-foil distances were
more susceptible to AWC dust dislodgment patterns than those with greater distances. 15
FMSHRC at 1515, 1521. In the Common Issues Decision, the judge concluded that the cited
filters had Ashorter filter-to-foil distances than those manufactured subsequently.@ Id. at 1515-16.
In the Keystone Decision, he concluded that the cited filters Amore probably than not had shorter
filter-to-foil distances than those manufactured subsequently@ and that this Acould have been a
factor in the decline of cited AWCs [at Urling] in the Spring of 1990.@ 16 FMSHRC at 885-86
(emphasis added).

The Secretary asserts that the judge erred in several respects in his analysis of filter-to-foil
distances and other manufacturing variables of dust sampling cassettes in reaching his conclusion
that accidental and incidental impacts could have caused Urling=s AWCs. PDR at 16-17; S. Br. at
78-88. First, the Secretary argues that the judge=s findings that filter-to-foil distance affects the
likelihood of AWCs and that the cited filters had shorter filter-to-foil distances are not supported
by substantial evidence. PDR at 16; S. Br. at 78-81. Second, he argues that, in Keystone, the
evidence does not show that filter-to-foil distances or other variables associated with the
manufacturing process changed over time. PDR at 16-17; S. Br. at 82-83. He also contends that
the statistical evidence in Keystone does not support a finding that manufacturing variables caused
Urling=s AWCs or a sudden decline in their rate of occurrence. PDR at 17; S. Br. at 87. In
response, Keystone and Intervenors contend that there was ample evidence that manufacturing
variables influenced the frequency of AWCs. I. Br. at 26; K. Br. at 80-81. Keystone further
48
This section addresses Issue No. 9 in the PDR. The Secretary=s briefs fail to provide
support for the argument set forth in section (c) of that issue, dealing with changes in floppiness
of filters over time, and we do not address it. The judge found in his Common Issues Decision
that floppiness or tautness of the filters varied and that a floppy filter was more prone to AWC
formation than a taut one. 15 FMSHRC at 1515. In his Keystone Decision, the judge,
referencing Dr. Marple=s testimony that floppiness was Aassociated with smaller filter to foil
distances,@ stated that the Aevidence related to the question whether the more recently
manufactured filters were floppier than the older ones is not sufficiently clear,@ thus precluding his
making a finding on this issue. 16 FMSHRC at 885 n.3.

47

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Page 48

asserts that there is record support for the judge=s crediting of Lee=s testimony that its cited filters
had shorter filter-to-foil distances and were more susceptible to accidental or incidental AWC
formation than filters manufactured later. K. Br. at 79. After reviewing these contentions and the
record evidence, we affirm the judge.

a. Filter-to-foil Distance and Susceptibility to AWCs

In the Common Issues Decision, the judge found that shorter filter-to-foil distance makes
a filter more prone to AWC formation. 15 FMSHRC at 1515. He credited the testimony of the
operators= experts, Drs. Lee, Grayson, McFarland and Corn, that filter-to-foil distance was an
important characteristic of filter cassettes that varied with date of manufacture and that a shorter
filter-to-foil distance made a filter more susceptible to AWC formation. (Lee) R. Ex. 1001, at ii;
Tr. 6225, 6238-41; (Grayson) Tr. 5551, 5648; (McFarland) Tr. 5183-85, 5196, 5321; (Corn) Tr.
7567, 7697-98.

As noted, Dr. Lee was accepted as an expert witness in physics, materials characterization
and analysis, and environmental monitoring. 15 FMSHRC at 1488. Using a stereo optical
microscope, Dr. Lee measured the filter-to-foil distance of the 3,100 samples generated in his dust
tunnel as well as 650 samples taken from coal mines across the country. Id. at 1489; R. Ex. 1001,
at 1, 11. Based on his tests of subjecting cassettes to drops and hoses to impacts, Dr. Lee
concluded that filter-to-foil distance was the strongest factor influencing susceptibility to AWC
formation. 15 FMSHRC at 1491; Tr. 6238-39; R. Ex. 1001, at 11, 15. In tests of dropping
cassettes a distance of 4 feet, 33% of 30 filters with filter-to-foil distance of 1 mm or less had
potentially citable AWCs; 27% of 129 filters with a distance of 1 to 2 mm had potentially citable
AWCs; none of 43 filters with a distance of 2 to 3 mm had potentially citable AWCs; 4% of 52
filters with a distance of 3 to 4 mm and none of 5 filters with a distance of 4 to 5 mm had
potentially citable AWCs. 15 FMSHRC at 1491; R. Ex. 1001, at 11; App. B-4.3, B-4.7, B-8. In
tests of hose impacts using a one pound weight, 66% of 30 filters with a distance of 0 to 1 mm,
12% of 8 filters with a distance of 1 to 2 mm, none of 3 filters with a distance of 2 to 3 mm, 12%
of 30 filters with a distance of 3 to 4 mm, and none of 9 filters with a distance of 4 to 5 mm had
potentially citable AWCs. 15 FMSHRC at 1491; R. Ex. 1001, at B-5.2-5.3, B-5.6. Dr. Lee also
produced a video, R. Ex. 1006, which illustrated that, under the same conditions, it is easier to
produce an AWC with a short filter-to-foil distance than with a larger distance. Tr. 6241-53. Dr.
Lee explained that, as a matter of basic physics, it is easier to dislodge dust on a filter that is
closer to the foil. Tr. 6241; See 15 FMSHRC at 1515.

Dr. Grayson is dean of the College of Mineral and Energy Resources at West Virginia
University and has a doctorate in mining engineering. 15 FMSHRC at 1497; Tr. 5518-20; R. Ex.
1014C. He was accepted as an expert witness in aerosol mechanics, fluid mechanics,
thermodynamics, aerosol filtration, and engineering statistics. 15 FMSHRC at 1499. In his
research on filter-to-foil distance, Dr. Grayson measured the distances of 178 samples from
various mines by inserting a millimeter scale into the cassette inlet. Id. at 1498. Of those filters,
94 were drop tested and the remaining filters were examined for existing AWCs. Id.; Tr. 5644-

48

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Page 49

45; R. Ex. 1014, at 14-16. Dr. Grayson concluded that there was a strong relationship between
filter-to-foil distance and creation of AWCs. 15 FMSHRC at 1499; R. Ex. 1014, at 18.

Dr. McFarland is a professor of mechanical engineering and was accepted as an expert in
the fields of aerosol mechanics, fluid mechanics, thermodynamics, aerosol filtration, and
engineering statistics. 15 FMSHRC at 1499; Tr. 4480, 4548. Dr. McFarland measured the filter-

49

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Page 50

to-foil distances of several hundred cassettes. 15 FMSHRC at 1502; Tr. 4730-38, 4752. Based
on his tests of applying varying degrees of pressure to cassettes with varying distances between
the filter and the foil, Dr. McFarland concluded that it was more difficult to form AWCs on filters
with larger filter-to-foil distances. 15 FMSHRC at 1502, 1505, 1515-16; Tr. 5004-05 ; R. Ex.
1018, at 37.

As noted, Dr. Corn was qualified as an expert in aerosol and particle physics, including the
adhesion and dislodgment of particles and coal mine dust sampling technology. Tr. 7490; See
also 15 FMSHRC at 1496-97. Corn measured filter-to-foil distances and examined 1,248 of the
cited filters in reaching his opinion that a cassette with a shorter filter-to-foil distance is more
prone to dust dislodgment than one with a greater distance. Tr. 7562, 7591; R. Ex. 1037, at 2.

Thus, the operators= experts presented a scientific basis, not merely a Acommon sense@
view as alleged by the Secretary, S. Br. at 82, to support the effect of filter-to-foil distance on
susceptibility to dust dislodgment.

The testimony of the Secretary=s experts, Drs. Marple and Rubow, was inconsistent on the
influence of filter-to-foil distance and filter floppiness. The judge recognized that, although
Marple and Rubow concluded that manufacturing variables such as filter-to-foil distance and
floppiness were Anot probably contributing factors@ to dust dislodgment, Marple had also testified
that filter floppiness and the distance between the filter and foil influenced dust dislodgment
patterns. 15 FMSHRC at 1482-83; compare Tr. 2826, 9347-48; Gov=t Ex. 282, at 13 and Tr.
2692-93, 2803-04, 2820-21, 2841-42. The judge reasonably discounted the inconsistent
testimony of the Secretary=s experts on the effect of filter-to-foil distance and credited the
scientifically supported, consistent, and corroborated testimony of the operators= experts. Thus,
his finding that filter-to-foil distance affects the likelihood of AWCs is supported by substantial
evidence and we affirm it. In Keystone, the judge reiterated his holding in the Common Issues
Decision, that shorter filter-to-foil distance increases susceptibility to AWC formation.49 16
FMSHRC at 885.

49
The Secretary also requests the Commission to accept Marple=s uncontradicted
testimony identifying threshold velocity of dust particles, i.e., the air velocity that is required to
dislodge dust particles from the surface of filters, as the single most important factor in dust
dislodgment. S. Br. at 82. The judge found that both filter-to-foil distance and threshold velocity
were important factors in dislodgment. See 16 FMSHRC at 885, 899. There is no inconsistency

50

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Page 51

in the judge=s determination that both factors, one having to do with the physical characteristics of
dust and the other with the physical characteristics of the filter cassette (filter-to-foil distance),
were causative.

51

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Page 52

The Secretary also takes issue with the judge=s finding that the cited filters were from a
population of filters having short filter-to-foil distances. 15 FMSHRC at 1516; S. Br. at 78-79.
Lee testified, without contradiction, that 80% of the cited filters were from the series with
numbers 200,000 and 300,000.50 See Tr. 6271. See also 15 FMSHRC at 1515-16. Based on
certain graphs, the judge also found that, after the filters were loaded with dust, the filter-to-foil
distance for 80% of the series 200,000 and 95% of the series 300,000 filters was 2 mm or less.
15 FMSHRC at 1516; R. Exs. 1068-69.51

The Secretary asserts that the judge erred in relying on graphs that plotted filter-to-foil
distances for experimental filters in each series because the graphs were based on a small number
of filters with widely varying measurements. R. Exs. 1068-69; S. Br. at 79-81. He argues that
the judge made an Ainherently weak assumption@ that the very few experimental filters
manufactured before February 1990 were representative of all such filters. S. Br. at 80. The
Secretary also contends that the graphs Aat best showed only a slight tendency over time toward
an increase in the relative percentages of filters with filter-to-foil distances of more than

50
The series 200,000 filters were manufactured between April 20, 1988, and April 3,
1989, R. Ex. 1069; series 300,000 between April 3, 1989, and February 13, 1990, R. Ex. 1068;
series 400,000 between February 13, 1990, and October 25, 1990, R. Ex. 1070; series 500,000
between October 25, 1990, and August 5, 1991, Gov=t Ex. 259A; series 600,000 between August
5, 1991, and February 15, 1992, Gov=t Ex. 261A; series 700,000 between February 15, 1992, and
May 28, 1992, R. Ex. 1071; and series 800,000 from May 28, 1992, through the date of the
Common Issues trial, Gov=t Ex. 265A.
51
The graphs provide filter-to-foil distance measurements under two conditions, before
dust was loaded onto the filter, and after dust had been loaded. See Tr. 2880-81. The judge
analyzed both types of measurements and noted that the pre-loading values show a slight
tendency of filter-to-foil distance to increase in the later manufactured series. 15 FMSHRC at
1516. See Gov=t Exs. 253A, 255A, 257A, 259A, 261A, 263A.

52

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Page 53

2 mm . . . .@ Id. He further argues that 50% of the filters manufactured between October 25,
1990, and February 15, 1992, seven months to almost two years after institution of the void code,
had short filter-to-foil distances, and that the rarity of AWCs in that filter group refutes an
association between filter-to-foil distance and AWCs. Id. at 80-81.

The graphs in question were prepared by the Secretary and set forth the filter-to-foil
distances after dust loading for experimental filters manufactured between April 20, 1988, through
the time of the Common Issues trial; they were based on measurements by both the Secretary=s
and the operators= experts. 15 FMSHRC at 1516. In addition to showing that 80% of the series
200,000 and 95% of the series 300,000 filters had short filter-to-foil distances (2 mm or less) the
graphs showed that a lower percentage of filters in the later manufactured series had short filter-
to-foil distances: 45% in the 400,000 series; 50% in the 500,000 series; approximately 50% in the
600,000 series; and a little more than 40% in the 700,000 series. Gov=t Exs. 260A, 262A; R. Exs.
1070, 1071. Thus, the graphs support the judge=s finding that the cited filters, more than 80% of
which were from the 200,000 and 300,000 series, came from a population of filters with
comparatively shorter filter-to-foil distances. 15 FMSHRC at 1515-16. Dr. Rubow, Marple=s
colleague, acknowledged that the graphs showed a marked increase in the percentage of filters
with filter-to-foil distances greater than 2 mm in filters manufactured after February 1990. Tr.
9244-47.

Contrary to the thrust of the Secretary=s argument, the judge was mindful of the
limitations of the graphs. 15 FMSHRC at 1516. He recognized that the number of filters
measured from each series varied considerably and that the measurements in each series were
made by different experts who used different methods. Id. The judge noted, however, that,
because the cited cassettes had been disassembled without being measured, the graphs provided
the best available evidence of the filter-to-foil distance. Id.

Based on the evidence of record, we conclude that the judge=s finding in the Common
Issues Decision, that the cited filters came from a population of cassettes with shorter filter-to-foil
distance, more susceptible to AWC formation than those manufactured subsequently, is supported
by substantial evidence. Id. at 1515-16.

b. Filter-to-foil Distance and Decline of AWCs at Urling

In Keystone, the judge found that the cited filters probably had shorter filter-to-foil
distances than those manufactured subsequently. 16 FMSHRC at 886. He also found that the
decline in the number of cited AWCs in the spring of 1990 could be explained, in part, by this
manufacturing variable. Id.

The Secretary asserts that there was no evidence that filter-to-foil distance or other filter
characteristics, varying with date of manufacture, changed after March 26, 1990, or provide an
explanation for the decline in AWC rates after that date. S. Br. at 83; S. Reply Br. at 23.

53

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Page 54

All the cited Urling filters were series 200,000 and 300,000 filters. 16 FMSHRC at 885;
see K. Ex. 2133, R. Exs. 1068-69. As discussed supra, the judge, in the Common Issues
Decision, found that filters from these two series tended to have shorter filter-to-foil distances.
15 FMSHRC at 1515-16. The judge noted that, according to Dr. Lee, the Urling filters exhibited
physical characteristics indicative of shorter filter-to-foil distances. 16 FMSHRC at 885. Lee
testified that the absence of 9 mm segmented ring standoff patterns on the Urling filters correlated
with shorter filter-to-foil distance.52 K. Tr. 3874-79; R. Ex. 1001, at 15; K. Ex. 2001, at 5-6.
Dr. Marple concluded that the absence of standoff patterns did not indicate shorter filter-to-foil
distance because his experiments for the Common Issues trial indicated that, even when filters
were resting on the standoff, only 50% had standoff patterns. 16 FMSHRC at 885; Tr. 2528-29.
Nonetheless, Marple agreed that the presence of the standoff pattern was associated with greater
filter-to-foil distance; he found that standoff ring patterns appeared only on filters with filter-to-
foil distances greater than 3.7 mm. Tr. 2527-29, 9335-38, 9619-23; Gov=t Ex. 327. Lee also
testified, without contradiction, that the presence of crimping or pinching on 20% of the Urling
filters indicated shorter filter-to-foil distance. K. Tr. 3877-78; K. Ex. 2001, at 6. Lee noted that
the incidence of crimping on recently purchased filters was much lower, about 6%. Id.; 16
FMSHRC at 885.

We conclude that substantial evidence, including the testimony of Dr. Lee, which was
properly credited, as well as the testimony of Dr. Marple, supports the judge=s conclusion in
Keystone, 16 FMSHRC at 885-86, that the cited filters more probably than not had shorter filter-
to-foil distances than filters manufactured subsequently.

In arguing that the judge erred in finding that manufacturing variables provided an
explanation for a decline in AWC rates after March 26, 1990, S. Br. at 79, the Secretary
mischaracterizes the Keystone Decision. The judge merely considered filter-to-foil distance as
one of several factors that could account for a decline in AWCs at Urling in the spring of 1990.
16 FMSHRC at 882-86. The failure of manufacturing variables to explain completely a decline in
AWCs in the spring of 1990 does not substantiate the Secretary=s argument that the judge erred in
finding that such variables Acould have been a factor@ contributing to the decline. At oral
argument, the Secretary asserted that Athe judge owed it to us to analyze those data and tell us
what he thought was the most likely cause of these appearances.@ Oral Arg. Tr. 48. The judge
was not required to find a complete explanation for the downward trend in AWCs. The
Secretary, to preponderate, was required to show that the trend was the result of deliberate
tampering.

c. Statistical Analysis of Manufacturing Variables

In the Common Issues Decision, the judge, relying on Dr. Roth=s statistical analysis,
concluded that the evidence Adoes not establish . . . but may point to@ manufacturing variables as
52
The 9 mm ring standoff pattern is caused by the filter backing pad coming in contact
with the 9 mm plastic (standoff) supports on the cassette. Tr. 2526-27; Gov=t Ex. 328.

54

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Page 55

affecting the decline in AWC formation. 15 FMSHRC at 1520.53 In his Keystone Decision, the
judge noted that the statistical experts arrived at different conclusions on the effect of cassette
manufacturing date on AWC rate. 16 FMSHRC at 900. He found that manufacturing variability
may have played some role in AWC formation. Id. at 886, 900-01.

The Secretary challenges the judge=s analysis of manufacturing variables in Keystone,
asserting that Athe statistical evidence does not support a finding that manufacturing variables
caused AWCs or the sudden . . . change in AWC occurrences.@ PDR at 17. The Secretary
argues, based on Miller=s analysis, that, rather than the cassette manufacturing date, the most
significant date affecting the occurrence of AWCs was the sampling date and whether it was
before or after March 26, 1990, the date he alleges Keystone learned of the void code. S. Br. at
84-87. The Secretary further states that the judge failed to resolve conflicting testimony of Miller
and Roth on the relationship between manufacturing dates and AWC formation. Id. at 87-88. In
response, Keystone argues that Miller=s comparison of cassettes manufactured on certain dates
and used by R&P mines before and after March 26, 1990, was faulty because he failed to use data
for the same mines in the two periods. K. Br. at 109-10. Keystone further asserts that a valid
comparison, based on cassette manufacturing date, between R&P mines including Urling and
mines of other operators could not be made because of handling and sampling differences. Id. at
109.

53
The judge referred to Roth=s testimony and report, which showed that cassettes
manufactured before 1990 had an AWC rate that was 10 times higher than cassettes manufactured
after 1990. See Tr. 4128-30; R. Ex. 1041, at 3. See also Oral Arg. Tr. 168.

55

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Page 56

Dr. Roth=s analysis showed that the rate of AWCs at Urling was more than nine times
higher for cassettes manufactured on four consecutive key dates than on other manufacturing
dates, 46.9% as compared to 4.8%.54 K. Ex. 2004, at 6; 16 FMSHRC at 881, 900-01. Dr.
Miller=s analysis showed that, for non-R&P mines sampled before March 26, 1990, the citation
rate for cassettes manufactured on the key dates was 2.5%, lower than that for cassettes
manufactured on other dates, 6.2%. K. Gov=t Ex. 527, at 2-3, Table 1b; S. Br. at 85; 16
FMSHRC at 879. Miller also found, however, that, for all samples from R&P mines including
Urling that were taken before March 26, 1990, the citation rate for cassettes manufactured on the
key dates was 49.9%, higher than that for cassettes manufactured on other dates, 38.2%. 16
FMSHRC at 879; K. Tr. 760-61; K. Gov=t Ex. 527, at Table 1a.

Miller=s analysis that manufacturing date does not account for changes in AWC rates was
countered by Roth=s analysis that the rate of AWCs tended to be higher for cassettes
manufactured earlier. K. Ex. 2004, at 5-6; K. Tr. 3563, 3565. The judge explained that he saw
merit in both Miller=s and Roth=s analyses, i.e., that manufacturing in general did not explain
citation rates, but that cassettes manufactured on four key dates accounted for 60% of the AWCs
at Urling, suggesting manufacturing anomalies. 16 FMSHRC at 900-01. There is record
evidence that the dust cassettes were plagued by manufacturing problems. In July 1990, MSA,
the manufacturer of the dust cassette assemblies, recognized that filter airflow resistance
exceeding the allowed level and incompatibility of the filter and backing pad had to be corrected.
R. Ex. 1124, at 2-4; Tr. 9211-13. On August 23, 1990, MSA recalled from its district offices and
destroyed all cassettes manufactured before August 1, 1990. R. Exs. 1134, 1144; Tr. 9221-22.
This recall included all filters in the 200,000 and 300,000 series and part of the 400,000 series.
See note 50, supra. Shortly thereafter, MSA began screening all cassettes to ensure proper
airflow resistance. Tr. 9207-08, 9221-22; R. Ex. 1180. As the judge noted, 15 FMSHRC at
1481, Dr. Rubow, the Secretary=s expert, conceded that a filter with a higher airflow resistance
would be more likely to flex (and thereby be more susceptible to AWC formation) when exposed
to a constant reverse airflow. Tr. 9147-48. Dr. Lee similarly testified that reverse air pulses of
low magnitude would be more likely to form AWCs on filters with higher airflow resistance. Tr.
6214-16. Dr. Corn also testified as to his concern that changes associated with achieving proper
airflow resistance influenced the formation of AWCs. Tr. 8050-51.

54
The four key dates were: May 26, May 31, June 1, and June 2, 1989. Roth found that,
for all R&P mines including Urling, the rate of AWCs for cassettes manufactured on these dates
was 49.6% as compared to 5.8% for other dates of manufacture. K. Ex. 2004, at 6; 16 FMSHRC
at 880.

56

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Page 57

We affirm the judge=s refusal to infer tampering from Miller=s statistical analysis. Miller
used March 26, 1990, as the critical date in analyzing data on AWCs submitted by Keystone. The
judge determined that March 26, 1990, is not materially significant at Urling because R&P
personnel knew of the AWC investigation some six weeks prior to that date and Urling=s AWC
citation data show a significant overall decline beginning in September of 1989.55 16 FMSHRC at

900. Accordingly, the judge could reasonably diminish the weight accorded to Miller=s statistical
     analysis. Conversely, Roth=s analysis of the four key dates of cassette manufacture was not tied to
     March 26, 1990, was supported by record evidence of cassette manufacturing problems, and
     could reasonably be considered more probative by the judge. See Id. at 900-01.

Given the conflicting analyses of the experts, the judge was within his discretion in
refusing to draw an inference of tampering from these statistics. We emphasize that the judge did
not hold that manufacturing variables, in themselves, explained the decline in AWCs; rather, he
considered them as a factor, among others, that could account for the decline in AWC rates at
Urling. Id. at 885-86.

6. Judge=s Admission and Crediting of Dr. Lee=s Opinion on Scrubbers56

In Keystone, the judge found that, when the air was sampled in the vicinity of a continuous
miner with a scrubber, the dust deposits on filters were damper, had a higher threshold velocity,
and were more difficult to dislodge. 16 FMSHRC at 883. He noted that the experts expressed
conflicting opinions on the effect of scrubbers and their accompanying water sprays on dust
deposits.57 The judge concluded that the introduction of scrubber systems on the continuous
miners at Urling in 1989 and 1990 could have been a factor in the decline of AWCs during that
period. Id. at 882-83.

The Secretary raises two issues related to the judge=s findings and conclusion. First, citing
Rule 26 of the Federal Rules of Civil Procedure, the Secretary contends that the judge erred in
admitting Dr. Lee=s testimony on the effect of water sprays and scrubber systems because that
opinion had not been disclosed during discovery. PDR at 17; S. Br. at 89-90. Further, the

55
We have affirmed that determination as discussed infra in section D. 2. a.
56
This section addresses Issues No. 10 and 11 in the PDR.
57
The record shows that scrubbers were gradually introduced beginning in 1989 and early
1990. See K. Tr. 85-86, 2594, 2796-98.

57

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Page 58

Secretary asserts that Lee lacked the scientific background to offer such an opinion. PDR at 17;
S. Br. at 90-96. Keystone responds that the judge properly admitted Lee=s opinion because the
Secretary had notice of, and opportunity to rebut, the testimony. K. Br. at 87-88. Additionally,
Keystone argues that Lee was qualified to give an opinion on the effects of environmental
conditions and mining equipment. Id. at 86-87. After review of the record, we find neither of the
Secretary=s contentions well taken.
a. Admission of Dr. Lee=s Opinion

Under Rule 46 of the Federal Rules of Civil Procedure, a party must make known to the
court the action that he seeks and the grounds therefor. Fed. R. Civ. P. 46; In Re Bildisco, 682
F.2d 72, 82 (3d Cir. 1982), aff=d on other grounds, 465 U.S. 513 (1984); accord Browzin v.
Catholic Univ. of Am., 527 F.2d 843, 850 & n.15 (D.C. Cir. 1975). See also section
113(d)(2)(A)(iii) of the Mine Act, 30 U.S.C. ' 823(d)(2)(A)(iii). Here, the Secretary failed to do
that. Several times during the Keystone trial, the Secretary objected specifically to Lee=s opinions
on other issues on the grounds that they had not been disclosed during discovery. K. Tr. 3781-
83, 3865-66, 3883. When Keystone questioned Lee as to whether an increase in the water
pressure of scrubbers, with an accompanying greater water spray, would affect the susceptibility
to dislodgment of dust samples, however, the Secretary raised no objection. K. Tr. 3891. The
judge then asked whether the increase in water pressure would increase or decrease the
susceptibility, and Lee answered that the pressure increase would decrease the susceptibility to
dislodgment. K. Tr. 3892. The Secretary again failed to object to Dr. Lee=s testimony on the
effect of scrubbers on susceptibility of filters to dust dislodgment. Indeed, the Secretary
subsequently questioned Dr. Lee as to how he arrived at his opinion on the effect of scrubbers.
K. Tr. 4043-45.

The portion of the transcript that the Secretary cites in support of his contention, K. Tr.
3894, pertains to another matter. He has apparently confused questions to Dr. Lee related to
whether Aoverall water levels and moisture levels in the Urling One Mine [that] increased between
1990 and 1993" affected the susceptibility of filters to dust dislodgment, to which he raised
objections, with earlier questions regarding the use of scrubbers between 1989 and 1990 (see
Stips. 85, 93, and 94),58 which coincided with the general decline in AWCs, to which he raised no
objection.59

In any event, even if the Secretary had timely objected to questions regarding the effect of
scrubbers, the testimony would have been properly admitted. As noted with respect to the
Secretary=s Rule 26 objection to the testimony of Dr. Corn, the judge stated at the Common

58
In their stipulations, the parties included facts relating to the use of scrubbers on
continuous miners at Urling and specifically identified those miners that had scrubbers. Stip. 94.
59
The judge was unable to draw conclusions from the evidence before him concerning the
increased moisture levels in the mine in 1993 as compared to 1989 and 1990 and the decline in
AWCs in late 1989 and 1990. 16 FMSHRC at 883.

58

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Page 59

Issues pretrial conference that, at trial, Athe expert witnesses should be able to testify in support of
their own conclusions, their own opinions and should be able to respond to criticism by other
experts and should be able to criticize and attack the reports of experts on the other side.@ Tr. 23-
24 (Prehr=g Conf. Nov. 17, 1992). Dr. Lee=s testimony falls squarely within the parameters of the
judge=s ruling.

Further, the primary report submitted by Dr. Lee in the Keystone proceeding set forth his
opinion that lower relative humidity, in existence in the winter months, increases the susceptibility
of filters to dust dislodgment. K. Ex. 2001, at 14. In response to Dr. Lee=s report, the
Secretary=s expert, Dr. Marple, stated:

[T]he important parameter to consider is the moisture content
of the particles and not the relative humidity of the air outside
of the mine or even in the mining environment. When the coal
is mined, there are water sprays from the mining machine on the
coal face providing a very wet local atmosphere in the generated
dust, independent of the months identified in Dr. Lee=s report.

K. Gov=t Ex. 509, at 10. At the Keystone trial, Dr. Marple testified further on the effect of
scrubbers: AI think the wetness of the particles would have a major effect which would be related
back to water sprays.@ K. Tr. 1551. Dr. Lee=s subsequent testimony regarding scrubbers was
made in response to Marple=s report and testimony. See also K. Tr. 4042-44. Thus, under the
judge=s pretrial ruling, which was within his discretion, Lee=s testimony was admissible, even if not
disclosed during discovery.60 See Fed. R. Civ. P. 26(a)(2)(B); Phil Crowley, 601 F.2d at 344.

b. Crediting of Dr. Lee=s Opinion

The Secretary challenges the expertise of Dr. Lee to give an opinion on the effect of
scrubber systems on dust deposits, arguing that the issue was outside the area in which he was
qualified, and that Dr. Marple=s credentials were more directly related to this issue. S. Br. at 90-

91. In response, Keystone notes that Dr. Lee was the only expert to research systematically the
    effect of humidity and water on AWC formation and that his testimony on the effect of scrubbers
    was consistent with his basic opinion that moisture content of coal was a factor that affected
    susceptibility to AWCs. K. Br. at 86-87. Intervenors argue that Dr. Lee=s opinion was consistent
    with testimony of all experts at the Common Issues trial and that Dr. Marple=s testimony also
    indicated that a variety of factors, including humidity, could affect the threshold velocity needed
    to dislodge dust particles from filters. I. Br. at 50-52.

60
The cases on which the Secretary relies, S. Br. at 90, to support the proposition that his
testimony should have been excluded are inapposite. See Weiss v. Chrysler Motors Corp., 515
F.2d 449, 457-58 (2d Cir. 1975); Freund, 956 F.2d at 356-59.

59

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Page 60

The Secretary failed to lodge an objection to Lee=s testimony on this subject during the
trial. As with the Secretary=s contention that the judge erred in admitting Lee=s testimony because
it was not disclosed during discovery, the Secretary was obliged to lodge a timely objection to the
testimony in order that the judge could consider the issue of Lee=s qualifications to give an
opinion on this issue. See Fed. R. Civ. P. 46; Browzin, 527 F.2d at 850 & n.15; 30 U.S.C. '
823(d)(2)(A)(iii).

In any event, Lee was fully qualified to offer an opinion on this subject. As noted, he has a
doctorate in solid state physics and was accepted as an expert witness in physics, materials
characterization and analysis, and environmental monitoring. 15 FMSHRC at 1488; see R. Ex.
1001A. The R. J. Lee Group, which Dr. Lee headed, was experienced in analyzing air samples
and particulate matter and had worked for numerous government agencies, as well as for private
industry. See Tr. 5923-48. A portion of his expert report dealt with the impact of humidity on
the susceptibility of filters to dislodgment. See K. Ex. 2001, at 14. Lee=s opinions were based on
his water spray experiments performed for the Common Issues trial. K. Tr. 3893. The Secretary
offers no persuasive argument to support his contention that Dr. Lee=s testimony was outside his
area of expertise. See S. Br. at 90-91. Rather, he argues that Dr. Marple, who testified that
water sprays do not reduce the susceptibility of dust deposits to dislodgment, K. Tr. 4145-49, was
more qualified to testify in this area. S. Br. at 90-91. However, Athe resolution of conflicting
testimony, including that of expert witnesses, is for the trier of fact.@ Jackson, 422 F.2d at 1275
(citations omitted); see also L & J Energy, 57 F.3d at 1088.

Here, the judge weighed partially conflicting testimony and determined that the use of
scrubbers and water sprays would reduce the susceptibility of filters to dust dislodgment. 16
FMSHRC at 883. He noted inconsistencies in Marple=s testimony regarding the effect of water
sprays. Id. at 875. Marple testified that water sprays do not reduce the susceptibility of dust
deposits to dislodgment, K. Tr. 4145-50, but he also testified that wetness of coal dust caused by
scrubbers affects susceptibility to dust dislodgment, K. Tr. at 1551-52. We further note that
Marple testified in the Common Issues trial, in response to a question from the judge, that wet
particles would be more resistant to dislodgment. Tr. 3103-05; see also Tr. 9498-9500. The
judge was well within his discretion in crediting Dr. Lee=s opinion over Dr. Marple=s.

Finally, the Secretary argues that the installation of scrubbers systems does not explain a
decline in AWCs after March 26, 1990. S. Br. at 93. As noted in section C. 5. b., supra, the
Secretary mischaracterizes the Keystone Decision. The judge merely considered the installation of
scrubbers as one of several factors that could account for the decline in AWCs at Urling in late
1989 and early 1990. 16 FMSHRC at 883.

60

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Page 61

D. Statistical Issues61

61
This section addresses Issues No. 7 and 8 in the PDR, which are set forth in terms of
the Keystone Decision. The Secretary Aconcurrently objected to@ related findings and conclusions
in the Common Issues Decision. PDR at 10 n.1; S. Br. at 40 n.15.

61

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Page 62

In the Common Issues trial, the Secretary attempted to establish, through the use of
statistics, that AWCs were not randomly distributed across the industry, that a sharp drop in the
rate of AWC citations across the industry occurred after institution of an AWC void code on
March 19, 1990, and that these factors, along with other evidence, established intentional
tampering by the cited operators.62 In support of his proposition that statistics can be used to
prove a causal relationship, the Secretary cited cases in which statistics were used to prove
discrimination in employment. The judge found that the susceptibility of filters to dust
dislodgment depended on a number of manufacturing and other variables and that the statistical
analysis of the Secretary=s expert failed to take those variables into account. 15 FMSHRC at
1521. He noted that the operators= statistical evidence showed that AWCs were non-random
after the void code was instituted as well as before and that the decline in AWC citation rate
commenced in September 1989. Id. at 1507-08; see also id. at 1485-86. The judge concluded
that, because of the existence of many other potential causes, the statistical evidence did not
establish that AWCs resulted from intentional tampering. Id. at 1519-22.

In Keystone, the Secretary attempted to establish, through the use of statistics, that a sharp
drop in Urling=s AWC citation rate occurred after March 26, 1990, the date the Secretary alleges
ESD personnel became aware of the void code,63 and that this drop established that Urling had
intentionally tampered. As noted in section C.5.c., supra, the judge refused to infer tampering
from the statistical evidence. He held that March 26, 1990, was not materially significant at
Urling and that the statistical evidence did not establish that a reduction in the mine=s citation rate
resulted from MSHA=s investigation of its dust sampling program. 16 FMSHRC at 900-01.

1. Common Issues Decision

62
The Secretary states: AThe institution of the AWC void code was the first official
notification to the mining industry that samples with AWC characteristics were considered by
MSHA to be abnormal and that some kind of government investigation into the AWC matter was
under way.@ S. Br. at 8-9.
63
In the Common Issues case, the Secretary used March 19, 1990, the date on which the
void code notices were issued by MSHA, asserting that this was the date on which operators were
advised of the voiding of filters with AWCs. 15 FMSHRC at 1460, 1486; S. Br. at 8-9. In
Keystone, he used March 26, 1990. 16 FMSHRC at 878.

62

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Page 63

In his PDR, the Secretary argues that the judge erred in failing to understand the
significance of the statistical evidence in supporting the conclusion that intentional tampering was
the likely cause of AWCs because such conduct was highly consistent with a dramatic decline in
AWCs in the spring of 1990 and other explanations are inconsistent with that decline. PDR at 15-
16.

The Secretary states that his use of statistics in the Common Issues trial was designed to
enable the judge to draw inferences regarding the conduct of the cited operators and to
corroborate the Secretary=s other evidence of intentional tampering. S. Br. at 36-37 n.12; S.
Reply Br. at 15. He asserts that the judge erred when he stated that A[s]tatistical evidence
alone . . . cannot prove causal relationships.@64 S. Br. at 36-37 n.12, quoting 15 FMSHRC at
1484 n.4. He contends that the judge had Aa legally erroneous understanding of what statistical
evidence can prove.@ S. Br. at 37 n.12. He submits that very significant weight should have been
given to the statistical evidence and cites discrimination cases, in which courts have determined
that statistics alone can constitute prima facie proof of employment or other discrimination.65 Id.
at 36-37 n.12. He also argues that Intervenors= attempts to explain AWCs do not comport with
the Secretary=s evidence that AWCs did not occur randomly over time and across the industry. S.
Reply Br. at 15-16.

Intervenors respond that the inference, if any, to be drawn from, and the weight to be
given to, the statistical evidence was within the judge=s sound discretion. I. Br. at 56. Intervenors
and Keystone argue that the statistical evidence deserved little weight because the underlying data
were merely allegations of tampering, not objective evidence of such conduct. Id. at 61-62,
referencing 15 FMSHRC at 1465-66; K. Br. at 94. They distinguish the discrimination cases as
analyzing fundamentally different data, i.e., objective facts, and as providing evidence of probable
relationships between variables, not proof of causal relationships. I. Br. at 57 & n.49. They note
that MSHA first developed written protocols for AWC identification in the spring of 1990 and
that the criteria for identifying AWCs also became more stringent then. Id. at 63. Intervenors
argue that the continuing non-random distribution of AWCs across mines after the void code
undermines the Secretary=s position. Id. at 69. Intervenors further argue that AWC rates had

64
Dr. Miller conceded at the Common Issues trial, however, that none of his studies
allowed him to conclude that the presence of an AWC on a filter Aestablishes that the weight of
the coal dust on that filter was intentionally altered . . . .@ Tr. 3740; see also Tr. 3806-07.
65
The Secretary relies on such discrimination cases as Hazelwood School District v.
United States, 433 U.S. 299, 307-08 (1977); International Brotherhood of Teamsters v. United
States, 431 U.S. 324, 339-40 (1977); Barnett v. W.T. Grant Co., 518 F.2d 543, 549 (4th Cir.
1975); Wetzel v. Liberty Mutual Ins. Co., 508 F.2d 239, 259 (3d Cir. 1975), cert. denied, 421
U.S. 1011 (1975); United States v. Jacksonville Terminal Co., 451 F.2d 418, 442 (5th Cir. 1971),
cert. denied, 406 U.S. 906 (1972); Alabama v. United States, 304 F.2d 583, 586 (5th Cir. 1962),
aff=d per curiam, 371 U.S. 37 (1962). S. Br. at 35-36.

63

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Page 64

dramatically declined for five months before institution of the void code and that the data reveal a
continuous decline throughout the period in question. Id. at 66. They point out that any date
selected during the period will result in a rate that is statistically significantly higher before that
date than after, and that the rate of decline was steeper before the void code date than after. Id. at
67-68. Intervenors further note the Secretary=s failure to explain the comparable rate of decline in
AWCs in the samples taken by MSHA inspectors before and after institution of the void code. Id.
at 68.

The statistical evidence on which the Secretary relies was based on cited filters submitted
to MSHA between August 8, 1989, and March 31, 1992. 15 FMSHRC at 1484. The data base

64

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Page 65

(the AAnalysis Data Set@) analyzed by Dr. Miller, the Secretary=s statistical expert, contains a
record of all respirable dust compliance filters submitted to MSHA during that period except
those from operators who pled guilty to charges related to submitting fraudulent samples. Tr.
3201-07; Gov=t Ex. 227, at 4-6. Miller concluded, on the basis of a chi-square analysis, that the
data were Ainconsistent with the hypotheses that the phenomenon leading to cited cassettes is
random and that the likelihood of cited cassette generation is the same at each mine.@ Gov=t Ex.
227, at 18. He also found Aa trend to decreasing cited rate over time@ and Aa marked decrease in
the cited rate on or about 3/19/90.@ Id. at 21.

Preliminarily, we agree that the data here are not objective. The Secretary asserts that the
AWC citations constitute objective data because the judge found Thaxton=s AWC determinations
to be consistent for purposes of the Common Issues case. The judge found in his Common Issues
Decision that Thaxton=s classifications were consistent and that his determinations as to whether
filters should be cited under his tamper codes Awere sufficiently consistent so that I must consider
whether an AWC establishes a violation.@ 15 FMSHRC at 1466-67, 1469. The judge declined,
however, to credit Thaxton=s opinion on AWC causation, finding that his opinion was not
supported by systematic scientific experiments. 16 FMSHRC at 897; see 15 FMSHRC at 1513,
1521. We have affirmed that conclusion. Thus, the data analyzed by Dr. Miller were merely
allegations of tampering.66

We find no error in the judge=s determination that the statistical evidence on non-
randomness was not persuasive of intentional tampering. Differences in AWC rates across mines
do not necessarily prove tampering.

66
The judge was correct in determining that this case is not analogous to a discrimination
case. 15 FMSHRC at 1464. Use of data derived from Thaxton=s decisions, even if consistent as
to which filters to cite, stands in marked contrast to the use of statistical data in employment
discrimination cases, where statistics are generally used to compare objective data as to two
groups. See, e.g., Teamsters, 431 U.S. at 336-42. For example, the racial makeup of a particular
category of a company=s workers is compared to the racial makeup of the qualified and available
labor pool. Absent discrimination, the percentages should be similar. The data used by the
Secretary in this case are not objective and, moreover, they are not compared to a second, control
group.

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Further, the drop in citation rate for the industry as a whole on March 19, 1990, derives
from data as to two different groups of mines. The data were analyzed based on certain Abefore@
and Aafter@ periods. The Abefore@ period included mines that submitted filters with AWCs before
March 20, 1990, and the Aafter@ period included mines that submitted filters with AWCs after
March 19, 1990. See Gov=t Ex. 241, at 1. The Abefore@ data included filters from 300 mines that
did not submit filters during the Aafter@ period. 15 FMSHRC at 1507; Tr. 4036-38. The Aafter@
period contained data on 762 mines that were not considered in the Abefore@ period. Id. Of the

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2,677 mines in the Secretary=s analysis, more than 1,000 were included in only one period, not
both. 15 FMSHRC at 1507-08; Tr. 4036-38. Thus, the data can prove nothing as to a change
over time for one group of mines or the other.

Moreover, the drop in the citation rate for the coal mining industry does not prove a drop
in the citation rate for all operators in the Common Issues proceeding. Some operators had
submitted their only cited sample some months before the void code date.67 Others received their
only citation for a sample taken many months after that date.68 In fact, many operators who
received multiple citations had not yet taken their first cited sample as of that date.69 The
statistical evidence presented by the Secretary in the Common Issues trial did not even prove that
many cited operators experienced a drop in citation rates at or near the void code date.
67
For example, Big Fork Coal Co., Mine ID # 4401969, received its only citation for a
sample taken on September 22, 1989; C&N Coal Co., Mine ID # 1516336, received its only
citation for a sample taken on November 17, 1989; and Big Hill Coal Co., Mine ID # 1513300,
received its only citation for a sample taken on October 4, 1989. See Gov=t Ex. 272.
68
For example, Bullion Hollow Enterprise, Inc., Mine ID # 4404871, received its only
citation for a sample taken on April 2, 1991; LJ=s Coal Corp., Mine ID # 1516637, received its
only citation for a sample taken on October 25, 1990; and Wampler Brothers Coal, Inc., Mine ID

1516722, received its only citation for a sample taken on September 25, 1990. See Gov=t Ex.

272.
69
For example, Trojan Mining, Mine ID # 1502091, received its first of 12 citations for a
sample taken on July 11, 1990; Double M. Coal Co., Mine ID # 4405661, received its first of five
citations for a sample taken on October 22, 1991; and Soldier Creek Coal Co., Mine ID

4200077, received its first of three citations for a sample taken on June 11, 1990. See Gov=t Ex.

272.

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The Secretary has not alleged that the operators in this consolidated case were engaged in
a conspiracy or were in any way acting in concert to violate the Mine Act. Yet he has attempted
to use statistics on the citation rate for the coal mining industry as a whole not only to prove a
drop in the citation rate for all operators but to prove that the drop occurred because operators
learned of the AWC void code and, as a result, ceased deliberate tampering. The Secretary is
essentially asserting that a drop in the rate of allegations against coal mine operators as a group
provides legal support for the underlying allegations against particular operators. We conclude
that, absent a conspiracy charge, a drop in the citation rate for the industry as a whole cannot, as a
matter of law, be used to draw inferences regarding the conduct of all operators or to support a
finding of deliberate misconduct on the part of any. Based on that determination, we conclude
that the judge did not err in finding that the statistical evidence did not establish that AWCs
resulted from intentional tampering. See 15 FMSHRC at 1520.

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2. Keystone Decision

The judge, refusing to infer tampering from the statistical evidence, held that March 26,
1990, was not materially significant at Urling. He was unable to conclude on the basis of the
statistical evidence that the reduction in the citation rate at Urling was related to MSHA=s
investigation of the dust sampling program at the mine. 16 FMSHRC at 901.

In his PDR, the Secretary argues that the judge erred in failing to understand the
significance of the statistical evidence in supporting the conclusion that intentional tampering was
the likely cause of AWC formation because such conduct was highly consistent with a sharp
decline in AWCs on March 26, 1990, and other explanations are inconsistent with that decline.
PDR at 15-16. Further, the Secretary asserts that the judge erred in his analysis of the statistical
evidence Aby focusing, inter alia, on the bimonthly sampling period rather than recognizing the
self-evident and paramount importance of March 26, 1990, as a discrete and most logical date for
evaluating rates of AWCs.@ Id. at 16.

In support of the petition, the Secretary argues that the record establishes that Urling
submitted 74 filters with AWCs during the seven months preceding March 26, 1990, but only one
AWC after that date, and that AWC rates for other R&P mines were similar. S. Br. at 37-38.
The Secretary asserts that whatever was causing the AWCs effectively ceased on March 26, 1990,
and the most likely explanation was the response of R&P employees to the AWC void code. Id.
at 37-40. The Secretary further argues that, even assuming R&P employees had sufficient
knowledge of the MSHA investigation to consider altering their conduct prior to March 26, 1990,
that date is of critical importance because it is when they learned that tampering would no longer
yield positive results for R&P. Id. at 45-46. He also argues that the analysis of AWCs on a
bimonthly basis masks a dramatic decline after March 26, 1990. Id. at 46-48. Finally, the
Secretary asserts that Keystone=s attempts to explain the occurrences of AWCs are unsatisfactory.
S. Reply Br. at 15-16; see also id. at 20, 26, 27.

Keystone responds that substantial evidence supports the judge=s decision. It asserts that
the Secretary=s analysis is flawed. It states that the date on which Keystone was alleged to have
gained knowledge of the void code, March 26, 1990, is irrelevant because their personnel were
aware almost two months prior to that date of a criminal investigation into dust sampling
conducted by MSHA. K. Br. at 94-99. Keystone also argues that, even if these flaws in the
Secretary=s analysis are ignored, the statistical evidence does not establish that AWCs resulted
from tampering. Id. at 94.

a. Significance of March 26, 1990

The judge concluded that March 26, 1990, was not the most logical cutoff point for
comparing AWC rates. 16 FMSHRC at 900. He found that Athe evidence shows that the ESD
personnel and Keystone management were aware of the investigation . . . 6 weeks or more before
the notification of the void code . . . .@ Id.

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In early February 1990, Dennis Hellgren, the Director of Safety for R&P mines, learned
that MSHA was investigating R&P=s dust sampling program. 16 FMSHRC at 888. He had
received a telephone call from the superintendent of the Florence No. 2 mine, who related that
two foremen, Charlie McGinnis and Norm Thompson, had been contacted by MSHA special
investigators, who were looking into R&P=s dust sampling program. Both foremen had taken
notes of their interviews with the MSHA investigators, and those notes were sent to Hellgren.70
Hellgren knew that special investigators normally handled criminal investigations. K. Tr. 2490-

91. From his review of the notes, Hellgren knew that the investigators were asking questions
    concerning cassettes with white centers and tampering. K. Tr. 2476-78, 2492-97; see 16
    FMSHRC at 888. He called the superintendents of other R&P mines to find out whether MSHA
    investigators had contacted their foremen about the dust sampling program and asked them to
    report back to him. K. Tr. 2477-78, 2486-88; K. Ex. 2073; see 16 FMSHRC at 888.

Hellgren called but was unable to reach the MSHA agent in charge of special
investigations at the local district office; instead, he spoke to an investigator, who confirmed that
MSHA was collecting information but who refused to explain the reason. K. Tr. 2478-79. On
February 2, while Hellgren was present, Edward Onuscheck, a former vice-president of safety and
a consultant to R&P, had a telephone conversation with Jerry Spicer, an MSHA supervisor.
Spicer said that a preliminary inquiry, on a nationwide basis, was being made into respirable dust
sampling. K. Tr. 2479-84; K. Ex. 2073; see 16 FMSHRC at 888.

On or about February 3, after reviewing Thompson=s and McGinnis=s notes, Hellgren
showed them to Donald Eget, supervisor of R&P=s ESD laboratory, and asked Eget what he
thought the investigators were seeking. K. Tr. 2299-2300, 2497-98; see 16 FMSHRC at 888.
Other employees of the ESD laboratory also learned of the MSHA investigation. Dust technician,
Robert Bollinger, Sr., knew about the investigation because MSHA investigators came to his
home looking for his son, who was a foreman at an R&P mine. K. Tr. 3016-19. Shawn Houck,
who worked under Eget=s supervision, learned of an MSHA investigation from Bollinger. K. Tr.
2120-21. Foreman McGinnis told Thomas Hollern, a dust technician in the R&P laboratory,
about the MSHA investigation in early February. K. Tr. 3256-58, 3294. Douglas Snyder and
Herbert Gleditsch, other dust technicians, also learned of the MSHA investigation and knew that
investigators were talking to foremen. K. Tr. 1908-11, 2677-78, 2728.

70
Thompson=s notes are dated January 25, 1990, K. Ex. 2075, while McGinnis=s are
dated February 1, 1990, K. Ex. 2076. McGinnis=s notes indicate that he was interviewed at his
home and shown dust filters with AWCs. Id.; see K. Tr. 2496-97. Neither Thompson nor
McGinnis testified at trial.

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On February 20, 1990, an MSHA investigator, Joe Totorio, telephoned Hellgren to set up
a meeting with R&P officials. Totorio indicated to Hellgren that MSHA was working with the
U.S. Attorney=s office in investigating dust cassettes with white spots in the centers. Hellgren
asked Totorio which of the R&P mines were being investigated and was told that Urling was one.
In a second telephone conversation that day, Totorio identified the lawyer from the U.S.
Attorney=s office with whom he was working. K. Tr. 2499-2507; K. Ex. 2074; see 16 FMSHRC
at 888. Following these conversations, Hellgren told R&P=s legal department that the company
was Aunder investigation by the U.S. Attorney.@ K. Tr. 2507-08. Hellgren also told Eget about
the conversation with Totorio. K. Tr. 2300-01, 2508-09; see 16 FMSHRC at 888.

To summarize, beginning in early February 1990, officials at R&P, from its top
management to its first-line supervisors, had knowledge of MSHA=s investigation into dust
cassette tampering. A mine superintendent first telephoned R&P=s safety director to report
MSHA=s efforts to interview foremen, and he in turn put every R&P mine superintendent on
notice to report any MSHA contacts with foremen. The safety director=s February 20 telephone
conversation with an MSHA investigator confirmed that the investigation involved allegations of
criminal misconduct. In early February and again on the 20th, details of the investigation were
passed along to Donald Eget, whom the judge found had an opportunity to tamper with dust
cassettes. 16 FMSHRC at 888-89, 901; K. Tr. 2495-98, 2508-09. These communications
diffused knowledge of the investigation among R&P managers. ESD laboratory employees,
including dust technicians, also became aware of the investigation. 16 FMSHRC at 890-92; K.
Tr. 1908-11, 3016-19, 3355-59.

Substantial evidence in the record supports the judge=s finding that R&P employees were
aware of MSHA=s criminal investigation some six to seven weeks prior to MSHA=s notification
that dust sample filters with AWCs would be voided. 16 FMSHRC at 900. Further, we reject the
Secretary=s argument that, even if R&P employees knew of the investigation earlier, March 26,
1990, is critical because they learned on that date that tampering would no longer be beneficial.
The Secretary has presented us with no evidence of why, if R&P personnel had been tampering
with dust cassettes, they would have been more likely discouraged by the institution of the void
code than by the special investigation and the prospect of criminal prosecution. We also note
that, from early February 1990, the time the judge found R&P=s employees had knowledge of the
investigation, until March 26, 1990, Urling=s citation rate actually rose sharply, from zero in the
sampling weeks of February 5, 12 and 26, to 50% in the week of March 19, 1990. K. Gov=t Ex.
501.

Significant to the judge=s rejection of Miller=s analysis of the rate of AWCs at Urling
before and after March 26, 1990, was the unexplained overall decline in the rate of AWCs from
September of 1989 through April of 1990. 16 FMSHRC at 900. Indeed, in other periods prior to
March 1990, the rate of AWCs also decreased, sometimes more sharply than it did after March

26. See 16 FMSHRC at 905 (App. A); K. Ex. 2129B; K. Gov=t Ex. 500, at Attach. A1.
    Although the Secretary states in his brief that Athe data picked the date,@ S. Reply Br. at 21, Dr.
    Miller testified that the date March 26, 1990, was given to him by the Secretary=s trial counsel for

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use in his analysis. K. Tr. 788-789. The Secretary offered no explanation, see Oral Arg. Tr. 116-
17, to distinguish earlier declines in the rate of AWCs from the decline that occurred after March
26, 1990, which he asserts is indicative of the cessation of intentional tampering.

We affirm the judge=s conclusion that the date March 26, 1990, is not materially significant
in the Keystone proceeding and that the drop after that date in Urling=s citation rate does not
establish intentional tampering.

b. Use of Bimonthly Data71

The Secretary challenges the statistical analysis of the rate of AWCs by Keystone=s expert,
Dr. Roth, because it was based on bimonthly data, which the Secretary alleges masks the decline
after March 26, 1990.72 S. Br. at 46-48. The judge accepted Roth=s approach in using bimonthly
data because operators carry out dust sampling on a bimonthly basis. 16 FMSHRC at 900; see 30
C.F.R. '' 70.207(a) & 70.208(a) (1994).

Miller conceded that, once March 26, 1990, loses its significance as the date on which
R&P employees became aware of the MSHA investigation, as the judge held and we have
affirmed, there was nothing Anecessarily wrong@ with using a two-month period to analyze the
rate of AWCs. K. Tr. 845-47. It is also apparent, from the judge=s consideration of Urling=s
AWC rate before and after March 26, 1990, that he also examined weekly data and did not rely
exclusively on Roth=s bimonthly analysis. 16 FMSHRC at 900, 905 (App. A). Thus, we conclude
that the judge did not err in relying in part on Dr. Roth=s analysis based on bimonthly data.

E. Exclusion of Third-Party Criminal Evidence73

Prior to the Common Issues trial, the operators sought to exclude the testimony of five
individuals on the Secretary=s witness list who were expected to testify about methods by which
dust could be deliberately dislodged from filters or fraudulent samples created. Mot. to Exclude
S. Case-Specific Witnesses from the Common Issues Trial, filed Nov. 12, 1992; Tr. 79-80, 85-88
(Prehr=g Conf. Nov. 17, 1992). Those individuals included Randy Thomas, a former R&P
employee, and a principal and an employee of Triangle Research Corporation (ATriangle@).

71
Bimonthly analysis has the effect of smoothing the data over time. 16 FMSHRC at

880. Compare 16 FMSHRC at 905 (App. A) with Id. at 906 (App. B).
     72
     In the Common Issues proceeding, Dr. Roth analyzed weekly data. See R. Ex. 1041,
     Attachs. B & C. In that case, Dr. Miller used March 19, 1990, rather than March 26, 1990, as the
     pivotal time in his analysis. 15 FMSHRC at 1485. We note that both experts tailored their
     analyses to the issues before the judge in the respective cases.
     73
     This section addresses Issue No. 14 of the PDR.

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S. Witness List filed Oct. 30, 1992. At the pretrial hearing, the judge granted the operators=
motion, excluding the testimony because it was not relevant to the issue to be determined in the
Common Issues trial, i.e., whether Aan AWC on a cited filter cassette . . . establishes that the
operator intentionally altered the weight.@ Tr. 82-83, 89 (Prehr=g Conf. Nov. 17, 1992).

At the Common Issues trial, the Secretary, in examining Mr. Thaxton on filters classified
as tamper code 10, sought to question him regarding Triangle and offered exhibits involving guilty
pleas of individuals and entities in criminal cases involving Triangle and its employees and other
operators.74 Tr. 294-96. He offered the evidence to show Athe accuracy of Mr. Thaxton being
able to discern which cassettes [had] been deliberately altered,@ and Aalso discern the method by
which they were altered.@ Tr. 296-97. The Secretary asserted that evidence of those guilty pleas
would show that, at least as to tamper code 10, Mr. Thaxton was very accurate. Tr. 296-97. The
judge sustained the operators= objection and excluded the evidence. Tr. 307. He let stand
Thaxton=s testimony that tamper code 10 filters came from a particular geographical area
(Kentucky, Virginia, and West Virginia) and were largely submitted by Triangle. Tr. 305. During
redirect examination of Thaxton, the Secretary renewed his request that the evidence be admitted,
again urging that it would show Thaxton=s ability to identify filters that had been deliberately
altered. Tr. 1115-20. Again, the judge sustained the operators= objection, finding the evidence
irrelevant and not necessary to rehabilitate Thaxton as a witness. Tr. 1119-20. The Secretary
made offers of proof regarding the five individuals whose testimony was excluded at the pretrial
hearing as well as several other documents involving criminal pleas. Excluded Exs. 330-34; Tr.
307-11, 1120; S. Statement and Intro. to Offers of Proof Reg. Potential Testimony of Pysher,
Murray, Thomas, Ellis, and White, filed Jan. 7, 1993.

In the PDR, the Secretary asserts that the judge erred in the Common Issues trial in
excluding evidence of criminal tampering and evidence from those who had witnessed or
participated in tampering because it would have played a substantial role, when weighed with
other evidence, in establishing that intentional tampering was the most likely cause of AWCs and
was Aclearly relevant to the general question of motive in tampering . . . .@ PDR at 20-21. He
further contends that the evidence of criminal conduct was relevant to showing the opportunity
and the incentive to tamper by R&P personnel, S. Br. at 101, S. Reply Br. at 49-50, and that the
judge=s ruling precluded Athe possibility of consideration of most of this evidence at the
[Keystone] hearing.@ S. Br. at 100.

Intervenors argue that the evidence was properly excluded under the terms of the
September 1992 Order, which provided that evidence of intent by individual mine operators was
not an issue in the Common Issues proceeding. I. Br. at 53-54. Keystone and Intervenors also
argue that the evidence was properly excluded at the Common Issues trial because it was neither
relevant nor probative and because evidence concerning operators who were criminally liable
74
Tamper code 10 was developed in the fall of 1990, after initiation of the void code.
Filters classified under this code had a slightly darker center, less than 6mm in diameter,
surrounded by a broad lighter ring. 15 FMSHRC at 1462; Tr. 292-93, 8264-65.

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could not be used to establish that other operators acted in a similar manner. Oral Arg. Tr. 198-
99; K. Br. at 52; I. Br. at 54.

We conclude that the judge did not err in excluding the evidence at the Common Issues
trial. As noted in section B. 3., supra, the judge, in the September 1992 Order, set forth the

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issue to be determined in the Common Issues trial as whether an AWC Aestablishes that the
operator intentionally altered the weight of the filter.@ 14 FMSHRC at 1677. AThe intent of a
particular mine operator or group of operators [was] not an issue in the common issues trial . . . .@
Id. Moreover, evidence that some AWCs were caused by deliberate conduct would not have
established that all or even most AWCs were caused by deliberate conduct. We conclude that the
judge=s evidentiary ruling is consistent with the September 1992 Order and was not an abuse of
discretion.

We also agree with Keystone and Intervenors that the evidence concerning guilty pleas by
several operators could not properly be used to establish motive, opportunity, incentive, or the
likelihood of intentional tampering as to others because such evidence does not prove that
operators, in general, had acted similarly.

Further, it is not apparent that, if the testimony regarding Triangle and the challenged
exhibits had been admitted into evidence, the judge would have analyzed tamper code 10 filters
differently. The evidence was proffered for the purpose of confirming Mr. Thaxton=s ability to
identify and categorize AWCs, particularly those in tamper code 10. The judge found the
evidence neither relevant to the case nor Anecessary to rehabilitate Mr. Thaxton as a witness.@ Tr.
1119-20. In fact, the judge found that Aclassification of AWCs by Thaxton under his tamper
codes was consistently applied . . . .@ 15 FMSHRC at 1513. Moreover, the judge allowed
testimony from Thaxton that the vast majority of tamper code 10 filters came from mines serviced
by Triangle, whose principal and employee were parties to a criminal plea agreement. Tr. 295,

305. Thus, the judge had before him evidence of criminal activity with respect to tamper code 10
     filters and referred to the criminal convictions in the Common Issues Decision. 15 FMSHRC at
     1520.

Contrary to the Secretary=s argument, S. Br. at 100-101, Oral Arg. Tr. 205, the judge=s
exclusion of the proffered evidence in the Common Issues trial did not preclude its consideration
in Keystone. Randy Thomas, one of the individuals whose testimony was excluded from the
Common Issues trial, testified as the Secretary=s witness in Keystone. K. Tr. 1307; 16 FMSHRC
at 892, 902. Further, at trial, after Keystone had cross-examined Thaxton using exhibits relating
to the criminal pleas involving Rushton Mining Company and Peabody Coal Company, those
exhibits were accepted into evidence on the Secretary=s motion. K. Tr. 1212-16, 1295-97; K.
Exs. 2117, 2118. Keystone Exhibit 2118 included criminal indictments and plea agreements
relating to Peabody and made up a portion of the Secretary=s Exhibit 334, which was offered and
excluded at the Common Issues trial. The Secretary did not offer into evidence any other
testimony or exhibits on this issue that were excluded from the Common Issues trial. Thus, the
Secretary=s argument on review, that the judge=s exclusion of this evidence in the Common Issues
proceeding precluded its consideration in Keystone, is without merit.

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F. Other Keystone Issues

1. Handling of Sampling Equipment at ESD75

The judge found that changes in the handling of sampling equipment at ESD could have
been a factor in the decrease of AWCs at Urling in the spring of 1990. 16 FMSHRC at 884. He
found that ESD supervisor Donald Eget, who handled the equipment more roughly than other
ESD personnel, did not handle samples or sampling equipment from April 9 until May 10, 1990,
and that dust technician Douglas Snyder and the other technicians were more careful in their
handling of the equipment as a result of MSHA=s investigation. Id.

The Secretary contends that substantial evidence does not support a finding by the judge
that changes occurring on or about March 26, 1990, in handling of dust sampling equipment at
ESD explained the decline in AWCs after that date. PDR at 18; S. Br. at 96-100. To support his
argument, the Secretary states that both Eget and his laboratory assistant Shawn Houck admitted
that they had not modified their handling practices after March 26, 1990. S. Br. at 97. He also
argues that Snyder could not identify the time at which he made changes in his handling of the
sampling units. Id. Keystone counters that the judge found handling changes in the spring of
1990 to be only one of many possible explanations for the decline. K. Br. at 103-07.

In asserting that the judge relied on changes in handling to explain the decline of AWCs
after March 26, 1990, the Secretary mischaracterizes the Keystone Decision. The judge found
that handling changes by ESD personnel, in addition to other phenomena at Urling, Acould have
been factors in the decrease in the number of cited AWCs in the Spring of 1990.@ 16 FMSHRC at
884; see also id. at 882-86. Substantial evidence supports that finding.

Eget, Houck, and Snyder testified that the sampling units had been subjected to rough
handling by ESD personnel. For example, Snyder testified that, in transporting pumps, he
dropped the pumps, caught protruding hoses on door latches, and slammed hoses in doors. K.
Tr. 1838, 1849-51. Houck testified that the dust technicians often left the pumps in disarray at
the ESD with pumps piled on top of each other and hoses tangled together. K. Tr. 2084-86,
2159-60. Eget was rough in his treatment of the pumps; for example, he carelessly threw pumps
into his vehicle when transporting them and swung pumps onto the table at the ESD laboratory.
K. Tr. 2178-80, 2244-48, 2250-52.

Houck testified that, although he did not know of any changes in the conduct of the
respirable dust program and that it was hard to reduce the rate of accidentally dropped cassettes,
he thought everyone, including the technicians, became Aa little bit more careful of the handling of
the pumps.@ K. Tr. 2179, 2203, 2214-15. Although Eget did testify that he had not changed his
behavior after March 26, 1990, he did not handle pumps from early April until May 10, 1990. K.
75
This section addresses Issue No. 12 in the PDR.

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Tr. 2319-20, 2362, 2384. Snyder could not pinpoint exactly when his behavior changed, but he
testified that he became more careful in his pump handling. See K. Tr. 1921. Other ESD dust
technicians also testified to using greater care. Dust technician Herbert Gleditsch, who at times
sampled at Urling, testified that he handled pumps more carefully. K. Tr. 2713-14, 2733-34.
Dust technician Thomas Hollern, who sampled at R&P=s Heshbon mine, testified that he became
more careful after the AWC investigation. K. Tr. 3272-76, 3283-84.

We conclude that substantial evidence supports the judge=s finding that changes in the
handling practices of ESD personnel did occur and we affirm that finding. We also affirm the
judge=s conclusion that these changes Acould have been factors@ causing the decrease in cited
AWCs in the spring of 1990.

2. Optional Quartz Samples76

The judge drew no conclusions with respect to the fact that no AWCs were noted or cited
by MSHA on the Aoptional quartz samples@77 concurrently submitted by Urling and other R&P
mines. 16 FMSHRC at 887-88. The Secretary asserts that the judge erred in failing to accord
weight to this evidence. PDR at 14-15; S. Br. at 48-55. He contends that the Urling and R&P
quartz sample filters did not display AWCs even though they were taken in the same manner,
under the same conditions, and at the same time as the respirable coal dust samples that exhibited
AWCs. Id. The Secretary asserts that the absence of AWCs on the quartz samples indicates
tampering because, for a quartz sample to be accepted as valid by MSHA, it must be sufficiently
heavy and, thus, R&P would not have had the same incentive to remove dust from a quartz
sample as from a compliance sample. S. Br. at 49-51; see K. Tr. 1109, 1122-24. Keystone

76
This section addresses Issue No. 6 in the PDR.
77
If a mine=s atmosphere contains more than 5% quartz, the maximum level of respirable
dust permitted is reduced below 2.0 milligrams per cubic meter. K. Tr. 1104-05; 30 C.F.R. ''
70.101, 71.101, 90.101 (below 1.0 milligrams per cubic meter where a Part 90 miner is exposed).
If more than 5% of quartz is detected in a sample drawn by an inspector, an operator is given the
option of submitting additional samples for evaluation. K. Tr. 1119. The results of the optional
quartz samples drawn by the operator are then averaged with the results of the inspector samples
to determine the mine=s respirable dust standard. K. Tr. 1119.

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responds that the judge properly rejected the Secretary=s evidence on optional quartz samples
because the appearances of those filters could not be evaluated. K. Br. at 90-92.

Paul Parobeck, chief of the instrumentation and analytical branch at the PHTC laboratory
and overseer of quartz sampling and the Secretary=s only witness on this issue, testified that none
of the quartz sample filters submitted by Urling and other R&P mines from August 1989 through
March 31, 1991, had AWCs. K. Tr. 1124-30. Parobeck=s testimony was based on computer
records, not on his personal examination of the filters. K. Tr. 1124-30, 1140; K. Gov=t Ex. 506.
The PHTC employees who had reviewed the filters were not called as witnesses. 16 FMSHRC at
887-88; see K. Tr. 1140-42. Moreover, the filters were no longer in existence78 and no
photographs of them were introduced at the trial or made available for examination prior to the
trial. 16 FMSHRC at 887; see K. Tr. 1128-30, 1140-41; K. Gov=t Ex. 506. Thus, the operators=
experts did not have an opportunity to examine the filters and compare them with cited filters or
form opinions about them. We conclude that the judge did not err in according no weight to the
Secretary=s evidence regarding Urling=s quartz sample filters or in refusing to infer from such
evidence that Keystone or R&P personnel had engaged in tampering.

3. Credibility of ESD Personnel79

Keystone, unlike the Common Issues case, involved allegations of tampering by the
employees of a specific operator. The judge=s evaluation of the credibility of employee witnesses
was critical and properly assumed a significant role in his decision. See 16 FMSHRC at 903. The
judge heard the testimony of 33 witnesses from Keystone and the ESD laboratory; all employees
of ESD during 1989 and 1990 testified. 16 FMSHRC at 859, 888, 901; see generally K. Tr. The
judge accepted as truthful the testimony of these employees that they did not tamper with dust
samples. 16 FMSHRC at 903.

The Secretary argues that the judge erred in several respects in his credibility
determinations as to ESD personnel. PDR at 18-19. He asserts that the judge gave undue weight
to the testimony and credibility of ESD witnesses and contends that the judge=s credibility
determinations are undermined because that testimony conflicts. He objects to the judge=s finding
that ESD personnel lacked incentive to tamper and he objects to the judge=s failure to credit the
testimony of Randy Thomas and Jack Szentmiklosi. Id. at 19. He also asserts that the judge=s
credibility determinations conflict with the overwhelming weight of the other evidence. Id. at 19-

20. Keystone responds that the judge=s credibility determinations are fully substantiated by the
    record and, in accordance with longstanding precedent, are entitled to significant weight. See K.
    Br. at 36-45, 53-57.

78
The quartz evaluation process itself destroys the quartz sample filters. K. Tr. 1112-13.
79
This section addresses Issue No. 13 in the PDR.

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The Commission has long held that a judge=s credibility determinations are not to be
overturned lightly and are entitled to great weight. Farmer v. Island Creek Coal Co., 14
FMSHRC 1537, 1541 (September 1992); Quinland Coals, Inc., 9 FMSHRC 1614, 1618
(September 1987); Penn Allegh Coal Co., 3 FMSHRC 2767, 2770 (December 1981); Hollis v.
Consolidation Coal Co., 6 FMSHRC 21, 25 (January 1984). ASince the ALJ has an opportunity
to hear the testimony and view the witnesses he is ordinarily in the best position to make a
credibility determination.@ Ona, 729 F.2d at 719. The Ona court observed that, Aas a general rule
courts are bound by the credibility choices of the ALJ, even if they >might have made different
findings had the matter been before [them] . . . de novo.=@ Id. at 719, citing Gulf States Mfrs., Inc.
v. NLRB, 579 F.2d 1298, 1329 (5th Cir. 1978).

The judge, noting several elements of demeanor that must be considered in determining
credibility, also recognized that his credibility determinations must take into account the extensive
factual, scientific, and statistical evidence and the witnesses= prior knowledge of sanctions for
tampering. 16 FMSHRC at 901. His analysis focused on Eget and Houck because he determined
that only they, among ESD personnel, had substantial opportunity to tamper. Id. In evaluating
their testimony, the judge stated that he was Aimpressed [with] the backgrounds of Eget and
Houck and their forthrightness on the witness stand@ and that he Acarefully considered their
testimony.@ Id. at 902. We conclude from our review of this record that the judge did not make
these credibility resolutions lightly. The judge found these individuals to be truthful witnesses and
his acceptance of their denials of tampering is linked to his careful consideration of the other
evidence. See id. at 903. Thus, the judge properly based his credibility determinations on his
evaluation of the witnesses and their demeanor and did so in the context of the record before him.

The Secretary argues that, in crediting ESD personnel, the judge overlooked a number of
inconsistencies in their testimony. S. Br. at 109-11 & n.38. The Secretary identifies two points
on which Eget and Houck differed: Eget did not regard his handling as rough, whereas Houck
did; Houck recalled performing a dust removal experiment that Eget did not remember. See PDR
at 18, citing 16 FMSHRC at 862, 890; S. Br. at 109-10. Neither of these differences provide
reason to discredit the witnesses or overturn the judge=s determination. The perception of one=s
own behavior frequently differs from how it is perceived by others. Eget=s failure to recall one
experiment does not make his testimony that he had not tampered unworthy of belief by the judge,
who had the opportunity to listen to his testimony and observe his demeanor. We conclude that
such insignificant differences in testimony do not provide sufficient basis to overturn the judge=s
credibility determinations.

The Secretary also argues that the judge erred in basing his decision to credit ESD
personnel on their lack of incentive to engage in tampering because they knew that tampering
could subject them to punishment. S. Br. at 106-07. Specifically, the Secretary contends that the
judge erred by: (1) failing to recognize that, on both Aan economic plane@ and Aa psychological
plane,@ employees have an incentive to help their employer; and (2) by stating that R&P=s small
number of respirable dust violations indicates a lack of incentive. Id. at 107-09. The judge

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expressly recognized that mine operators and agents had pled guilty to criminal tampering. 16
FMSHRC at 901. The judge=s statement as to lack of incentives responded to the Secretary=s
asserted motivation for ESD personnel to engage in tampering, i.e., to avoid penalties, to avoid
resampling, and to avoid the enormous potential costs of non-compliance. Id. at 902. The judge
rejected these asserted incentives as very weak and, when considered with R&P=s relatively small
history of dust violations, to be almost non-existent. Id. It was in this context that the judge
referenced the employees= knowledge of criminal sanctions and found, on balance, that the
evidence showed a lack of incentive rather than an incentive to tamper, as argued by the
Secretary. Id.

In addition, the record reveals that ESD supervisor Eget had a strong concern relating to
MSHA investigations into tampering and possible sanctions. See K. Tr. 2322-26. In 1982, Eget
wrote a memo cautioning safety personnel of the possibility of criminal investigations and advising
them to conduct themselves Ain a responsible manner and beyond reproach.@ K. Ex. 2036.
Because of an earlier MSHA investigation, Eget kept a logbook to record the appearance of every
sample sent to MSHA. K. Tr. 2260-61, 2377-80. Eget=s logbook noted that two of the filters
(369468 and 294719) submitted to MSHA and later cited would be voided for having been taken
on a low production shift. K. Ex. 2006A; K. Tr. 2279-80. We find no apparent incentive for
Eget to remove dust from filters that he knew were going to be routinely voided by MSHA.
Thus, the judge=s finding of lack of incentive is supported as to Eget.

As to other ESD personnel, dust technician Robert Bollinger, Sr. testified that he and
others who worked under Eget=s supervision had nothing to gain from tampering. K. Tr. 3035-

36. Dennis Hellgren, R&P=s Director of Safety, testified that he knew of no incentive for
    personnel to tamper. K. Tr. at 2540. Hellgren also stated that Eget would not have put up with
    tampering and that Hellgren would have fired Eget if he had tampered with filters. K. Tr. at 2541.

Further, a review of the record indicates that, before the judge, the Secretary neither
offered evidence on, nor argued his theory regarding, employees= incentive to help their
employers. We do not accept the Secretary=s theory as true on its face because even if, in much
of their behavior, employees have an incentive to help their employers, it is not evident that, in
general, they would engage in tampering or other illegal behavior to help their employers.
Consequently, we reject the Secretary=s theory as a basis for reversing the judge.

The Secretary argues that the judge=s reasoning with regard to the effect on incentives of
R&P=s small history of respirable dust violations is circular in nature, because the small history
itself may have resulted from tampering. S. Br. at 107-08. In deciding to credit denials of
tampering by ESD witnesses, the judge relied primarily on his evaluation of their truthfulness and
their demeanor in the context of the other evidence. 16 FMSHRC at 901-03. Before taking into
consideration R&P=s small history of dust violations, he found the Secretary=s asserted incentives
to be minimal. Id. at 902. Moreover, his determination as to ESD employees= credibility was
based only marginally on their lack of incentive. Thus, any error by the judge in relying on R&P=s
violation history is harmless.

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We also reject the Secretary=s assertion that the judge failed to give his reason for
discounting the testimony of Jack Szentmiklosi, that he had heard a conversation between
Bollinger and R&P=s then Vice-President of Operations, Robert Anderson, on the subject of the
tampering investigation. S. Br. at 110 n.39. As the judge explained, both Anderson and Bollinger
testified that they did not recall such a conversation. 16 FMSHRC at 891, 893. In choosing to
credit Bollinger and Anderson, the judge referenced the same reasons he had set forth earlier for
crediting Eget and Houck. Id. at 903. The PDR further takes issue with the judge=s discounting
of the testimony of Randy Thomas, who testified to alleged tampering at ESD some 15 years
earlier, PDR at 19; K. Tr. 1316-19, but the Secretary offers no support in his briefs for this
objection. We conclude that the judge did not abuse his discretion in weighing Thomas=s
testimony against that of Gary Foehrenbach and in determining that Thomas misunderstood what
he saw or that his recollection was dimmed by the passage of time. 16 FMSHRC at 902.
Finally, we reject the Secretary=s assertion that the judge=s credibility determinations Aare
entitled to no deference@ because they are irreconcilable with the weight of the evidence. S. Br.
at 103. The contrary evidence of tampering referenced by the Secretary, which he characterizes
as Aoverwhelming,@ i.e., Athat nothing explains the sudden and dramatic decline in AWCs except
the fact that on March 26, 1990, R&P learned that MSHA believed that the existence of AWCs
indicated tampering,@ id., provides no basis on which to overturn the judge=s credibility
determinations. We have affirmed the judge=s findings and conclusions as to the scientific and
statistical evidence as well as the handling of sampling equipment at ESD. Thus, in our view, the
judge=s crediting of ESD employees= testimony that they did not engage in tampering is not
irreconcilable with the record evidence but is in accord with it.

The Secretary=s contentions do not compel the extraordinary step of overturning the
judge=s credibility determinations.80 See Hollis, 6 FMSHRC at 25.

80
We have considered the cases on which the Secretary relies for extending diminished
weight to the judge=s credibility determinations. S. Br. at 28-30, 102-05, 110. Those cases offer
no support for the Secretary=s position; they recognize the general rule that, absent exceptional
circumstances, appellate courts do not overturn findings based on credibility resolutions. Medline
Industries, Inc. v. NLRB., 593 F.2d 788, 795 (7th Cir. 1979); Breeden v. Weinberger, 493 F.2d
1002, 1010 (4th Cir. 1974) (administrative law judge has unique advantage in making credibility
determinations); NLRB v. Brooks Cameras, Inc., 691 F.2d 912, 915 (9th Cir. 1982) (weight is
given to the administrative law judge=s determinations of credibility for obvious reasons). None of
the exceptions to the general rule on review of credibility resolutions presented in those cases
apply here. The judge=s determinations were not self-contradictory (Ona Corp., 729 F.2d at 719),
were not based on irrational criteria (Breeden, 493 F.2d at 1010), and did not contradict the
evidence (Medline, 593 F.2d at 795; NLRB v. Huntington Hospital, Inc., 550 F.2d 921, 924 (4th
Cir. 1977)). Unlike many of the Secretary=s proffered cases, see, e.g., NLRB v. Interboro
Contractors, Inc., 388 F.2d 495, 501 (2d Cir. 1967) (credibility determinations not supported by
record); Victor Products Corp. v. NLRB, 208 F.2d 834, 839 (D.C. Cir. 1953) (sense of record did
not support finding), the judge=s credibility determinations are supported by the record.

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III.

Conclusion

We have concluded that the judge articulated and applied the appropriate burden
of proof in both the Common Issues Decision and in the Keystone Decision. We have
determined that the judge did not abuse his discretion in rejecting Mr. Thaxton=s opinion on AWC
causation, in crediting Dr. Lee=s opinion on AWC causation, in admitting and crediting Dr. Corn=s
opinions on the effect of filter-to-foil distance and the size and shape of dust particles, and in
admitting and crediting Dr. Lee=s opinion on the effect of scrubbers. We have found that

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substantial evidence supports the judge=s findings that manufacturing variables affect the
susceptibility of filters to AWC formation and could have been a factor, among others, in the
decline of AWCs.

We have also affirmed the judge=s conclusion that the statistical evidence did not establish
that AWCs resulted from intentional tampering or that, in Keystone, a reduction in the mine=s
citation rate resulted from MSHA=s investigation of its dust sampling program. We have
concluded that the judge did not err in excluding evidence of criminal tampering from the
Common Issues trial and that its exclusion did not preclude its consideration at the Keystone trial.

As to Keystone, we have found that substantial evidence supports the judge=s finding that
changes in the handling of sampling equipment occurred at Urling and that those changes could
have been factors in the decrease in cited AWCs. We have also concluded that the judge did not
err in according no weight to the Secretary=s evidence as to quartz samples and have declined to
overturn the judge=s credibility determinations as to ESD personnel.

Accordingly, we affirm both the Common Issues Decision and the Keystone Decision.
The 75 citations at issue in Keystone are vacated.

The judge=s determination in the Common Issues Decision, i.e., that the presence of an
AWC on a filter does not, in itself, prove deliberate conduct and a violation of section 209(b),
applies to all citations in Master Docket 91-1. It serves as precedent on that issue in other dust
cases, not on the Master Docket, that have been stayed pending the outcome of this case.

Within 45 days after issuance of this decision, the Chief Administrative Law Judge shall
issue an order in the cases on stay, setting forth a schedule for submissions from the parties as to
disposition of those cases.

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Joyce A. Doyle, Commissioner

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Arlene Holen, Commissioner

Commissioner Marks dissents and will file his opinion later.

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