Can a plaintiff's lawyer also represent the plaintiff's treating expert witness at the expert's deposition in the same case?

Plain-English summary

A lawyer filed a wrongful-discharge claim for a plaintiff that alleges mental anguish. The defense subpoenaed the plaintiff's treating psychotherapist for a deposition about the plaintiff's mental state. At the start of the deposition, the lawyer announced he also represented the psychotherapist for the deposition, an arrangement made that morning, and the lawyer objected to questions and instructed the psychotherapist not to answer some. A court hearing was held mid-deposition on whether the psychotherapist had to answer, with the lawyer appearing for both the plaintiff and the psychotherapist. The opinion asks whether the lawyer may represent the psychotherapist in the deposition while representing the plaintiff in the claim, and answers yes, qualified.

The opinion analyzes the dual representation under Oregon RPC 1.7. On the limited facts, it concludes there is no conflict: the interests of the plaintiff and the psychotherapist are not directly adverse and may be aligned, since both may wish to keep psychotherapy matters out of the deposition, and even a neutral psychotherapist's different position on testifying would not be directly adverse. The opinion finds no reason that representing either would be materially limited by duties to anyone else, so no informed consent is required. It cautions that the lawyer may not advance the plaintiff's interest by instructing the psychotherapist not to answer a permissible deposition question, and that if the court ordered the psychotherapist to testify, the lawyer could not instruct otherwise.

The opinion notes conflicts could develop after the joint representation begins. If, for example, the psychotherapist gives testimony very damaging to the plaintiff, the lawyer might need to impeach the psychotherapist at trial; if the psychotherapist is still a current client, the lawyer's representation of the psychotherapist would be materially limited by the duty to impeach for the plaintiff, and the plaintiff's representation could be limited if the lawyer is unwilling to impeach the other client. In that event, Oregon RPC 1.7(a)(2) would bar continuing either representation without each client's informed consent confirmed in writing under RPC 1.7(b). A footnote flags other rules the facts could implicate, including RPC 7.3 (solicitation), 3.4(a), 8.4(a)(4), and 1.8(f).

In practice

The opinion holds that, under the current Oregon rules, simultaneously representing a party and that party's treating expert is permissible where their interests align and neither representation is materially limited, but it is inherently fragile: the same facts that make the representation proper at a deposition can shift if the expert's testimony turns against the client. Per the opinion, the analysis turns on whether the two clients' interests are directly adverse or whether one representation would be materially limited by duties to the other. Verify the current text of Oregon RPC 1.7 before relying on any specific point.

Common questions

Q: Can a plaintiff's lawyer represent the plaintiff's treating expert at the expert's deposition?

A: Yes, qualified. The opinion concludes that on these facts the interests are not directly adverse and may be aligned, so there is no conflict under Oregon RPC 1.7 and no consent is required.

Q: Can the lawyer instruct the expert not to answer deposition questions to protect the plaintiff?

A: Only proper instructions. The opinion states the lawyer may not advance the plaintiff's interest by instructing the expert not to answer a permissible question, and could not instruct against testifying if the court ordered the expert to testify.

Q: What happens if the expert's testimony ends up hurting the plaintiff?

A: Per the opinion, a conflict can then arise: if the lawyer would need to impeach the expert, Oregon RPC 1.7(a)(2) would bar continuing to represent both without each client's informed consent confirmed in writing.

Background and rules framework

The opinion interprets Oregon RPC 1.7 (current-client conflicts, including the directly-adverse test in 1.7(a)(1), the material-limitation test in 1.7(a)(2), and the consent conditions in 1.7(b)), corresponding to Model Rule 1.7.

Citations and references

Rules of Professional Conduct:

• Oregon RPC 1.7 / Model Rule 1.7 (current-client conflicts)
• Oregon RPC 1.0(b), (g) (confirmed in writing; informed consent)

Cases:

• Kidney Ass'n of Oregon v. Ferguson, 100 Or App 523, 786 P2d 754 (1990)

Other opinions cited:

• OSB Formal Ethics Op. No. 2005-122 (rev 2026) (multiple government clients; future waivers)
• OSB Formal Ethics Op. No. 2005-40 (rev 2026) (debtor and creditors)

See also

• OSB Ethics Op. 2005-110: Former Client as an Adverse Expert Witness
• OSB Ethics Op. 2005-86: Representing Husband and Wife
• OSB Ethics Op. 2005-122: Special Prosecutor, Private Clients, Advance Waivers

Source

• Landing page: https://www.osbar.org/ethics/toc.html
• Original PDF: https://www.osbar.org/_docs/ethics/2005-130.pdf