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Cal. Rules of Prof. Conduct, rule 1.9 · Chapter 1. Lawyer-Client Relationship

Duties to Former Clients

Verbatim from the official edition

Text — 2026 edition, as the State Bar of California publishes it (read October 22, 2026)

(a) A lawyer who has formerly represented a client in a matter shall not thereafter represent another person* in the same or a substantially related matter in which that person’s* interests are materially adverse to the interests of the former client unless the former client gives informed written consent.*

(b) A lawyer shall not knowingly* represent a person* in the same or a substantially related matter in which a firm* with which the lawyer formerly was associated had previously represented a client

(1) whose interests are materially adverse to that person;* and

(2) about whom the lawyer had acquired information protected by Business and Professions Code section 6068, subdivision (e) and rules 1.6 and 1.9(c) that is material to the matter;

unless the former client gives informed written consent.*

(c) A lawyer who has formerly represented a client in a matter or whose present or former firm* has formerly represented a client in a matter shall not thereafter:

(1) use information protected by Business and Professions Code section 6068, subdivision (e) and rule 1.6 acquired by virtue of the representation of the former client to the disadvantage of the former client except as these rules or the State Bar Act would permit with respect to a current client, or when the information has become generally known;* or

(2) reveal information protected by Business and Professions Code section 6068, subdivision (e) and rule 1.6 acquired by virtue of the representation of the former client except as these rules or the State Bar Act permit with respect to a current client.

Notes and commentary — not rule text

Comment

[1] After termination of a lawyer-client relationship, the lawyer owes two duties to a former client. The lawyer may not (i) do anything that will injuriously affect the former client in any matter in which the lawyer represented the former client, or (ii) at any time use against the former client knowledge or information acquired by virtue of the previous relationship. (See Oasis West Realty, LLC v. Goldman (2011) 51 Cal.4th 811 [124 Cal.Rptr.3d 256]; Wutchumna Water Co. v. Bailey (1932) 216 Cal. 564 [15 P.2d 505].) For example, (i) a lawyer could not properly seek to rescind on behalf of a new client a contract drafted on behalf of the former client and (ii) a lawyer who has prosecuted an accused person* could not represent the accused in a subsequent civil action against the government concerning the same matter. (See also Bus. & Prof. Code, § 6131; 18 U.S.C. § 207(a).) These duties exist to preserve a client’s trust in the lawyer and to encourage the client’s candor in communications with the lawyer.

[2] For what constitutes a “matter” for purposes of this rule, see rule 1.7(e).

[3] Two matters are “the same or substantially related” for purposes of this rule if they involve a substantial* risk of a violation of one of the two duties to a former client described above in Comment [1]. For example, this will occur: (i) if the matters involve the same transaction or legal dispute or other work performed by the lawyer for the former client; or (ii) if the lawyer normally would have obtained information in the prior representation that is protected by Business and Professions Code section 6068, subdivision (e) and rule 1.6, and the lawyer would be expected to use or disclose that information in the subsequent representation because it is material to the subsequent representation.

[4] Paragraph (b) addresses a lawyer’s duties to a client who has become a former client because the lawyer no longer is associated with the law firm* that represents or represented the client. In that situation, the lawyer has a conflict of interest only when the lawyer involved has actual knowledge of information protected by Business and Professions Code section 6068, subdivision (e) and rules 1.6 and 1.9(c). Thus, if a lawyer while with one firm* acquired no knowledge or information relating to a particular client of the firm,* and that lawyer later joined another firm,* neither the lawyer individually nor lawyers in the second firm* would violate this rule by representing another client in the same or a related matter even though the interests of the two clients conflict. See rule 1.10(b) for the restrictions on lawyers in a firm* once a lawyer has terminated association with the firm.*

[5] The fact that information can be discovered in a public record does not, by itself, render that information generally known* under paragraph (c). (See, e.g., In the Matter of Johnson (Review Dept. 2000) 4 Cal. State Bar Ct. Rptr. 179.)

[6] With regard to the effectiveness of an advance consent, see rule 1.7, Comment [9]. With regard to imputation of conflicts to lawyers in a firm* with which a lawyer is or was formerly associated, see rule 1.10. Current and former government lawyers must comply with this rule to the extent required by rule 1.11.

Source of truth

Edition
2026 edition, as the State Bar of California publishes it (read October 22, 2026)
Official file
https://www.calbar.ca.gov/sites/default/files/portals/0/documents/rules/Rules-of-Professional-Conduct.pdf (PDF pages 30–31)
Text hash
sha256 3dbb6a84ee35f01f915820570d45460ebd4ded6902d2b17d62e8d06ee10ac446
Composed by
rpc/build 2026-10-22: the State Bar's 2026 PDF (pages 12-71) read by two readers, PyMuPDF glyph positions and pdfminer with the PDF's tagged structure, agreeing on 834 of 843 paragraphs character for character, the other nine (paragraph boundaries only) resolved against the rendered page; 205,485 printed glyphs accounted for; the State Bar's chapter pages a third reading

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Procedural information only. Not legal advice and not a substitute for the advice of an attorney. Confirm the current text with the official publisher before relying on it.