May a lawyer sue a former traffic client for another client in an unrelated dispute?

Plain-English summary

The lawyer represented Client Y and had previously represented Y's former fiancé, X, in a traffic matter. Y then sought representation in an unrelated dispute against X. The question also asked about a demand letter and referrals to lawyers inside or outside the firm.

The answer addresses the proposed suit under Rule 4-1.9(b): the lawyer may handle it if no confidential information from the former traffic representation could be used to X's detriment. It says Rule 4-1.6 confidentiality is broader than the evidentiary attorney-client privilege and includes any information acquired from the prior representation. The published answer does not separately analyze the proposed demand letter or referrals.

Currency note

This opinion was issued in 1997, before Missouri's 2007 revisions to the Rules of Professional Conduct. Subsequent rule amendments or later opinions may have changed the analysis. Treat this page as historical context and verify current rules before relying on it.

Common questions

Q: What controls whether the lawyer may sue X?

A: Whether the lawyer obtained confidential information from representing X that could be used to X's detriment in the new dispute.

Q: Did the opinion separately decide demand letters and referrals?

A: No. The question raised those possibilities, but the published answer discusses the lawyer's handling of the suit.

Background and rules framework

The answer applies Rule 4-1.9(b) to adverse work against a former client and invokes Rule 4-1.6 for the broad scope of confidential information.

Citations and references

Missouri Rules of Professional Conduct:

• Rule 4-1.9(b)
• Rule 4-1.6

See also

• Missouri Informal Op. 970226: A Firm's Former Divorce Client
• Missouri Informal Op. 980006: Lien Against a Former Client

Source

• Landing page: https://mo-legal-ethics.org/informal-opinion/970212/
• Rule revision reference: Missouri Informal Opinion 20030007

Original opinion text

Reproduced from the official source for research purposes. The linked source is authoritative.

QUESTION: Attorney represents Client Y, who was at one time engaged to X. Attorney represented X on a traffic matter at the request of Client Y. Client Y has now asked Attorney for representation in an unrelated dispute with X. Is Attorney precluded from filing suit against X? Is Attorney precluded from issuing a demand letter to X? Is Attorney precluded from referring this matter to another attorney in Attorney´s firm? Is Attorney precluded from referring Client Y´s case to another attorney outside of Attorney´s firm? ANSWER: Under Rule 4–1.9(b) Attorney may handle the suit against X as long as Attorney did not gain any confidential information in the course of representing X that could be used to X´s detriment in the current matter. Confidentiality under Rule 4–1.6 is much broader than the attorney-client privilege which is a statutory evidentiary rule. Any information which came into Attorney´s possession as a result of the previous representation would be included under the ambit of confidential information.