Also known as: MR 1.9 · Rule 1.9 · duties to former clients
Written by attorneys · grounded in primary & secondary sources — see below
A rule of professional conduct that bars a lawyer who has formerly represented a client from representing another person in the same or a substantially related matter in which that person's interests are materially adverse to the former client unless the former client gives informed consent confirmed in writing. The rule also prohibits the lawyer from using information relating to the former representation to the disadvantage of the former client except when the information has become generally known or when permitted or required by the rules.
Mariam Mansour consulted with Malcolm McKinley about a potential product liability claim against a pharmaceutical company but never retained him. McKinley later joined a firm representing a plaintiff in a substantially related suit against the same company and used details from Mansour's consultation to shape discovery requests. The firm faces disqualification because the information would be protected under the former-client standard.
Marco Marquez worked at a firm that defended Mosaic Retail in employment litigation and acquired confidential strategy information. After joining a new firm, Marquez was screened from a substantially related case brought against Mosaic Retail by a former employee. The new firm may proceed only if it provides prompt written notice to Mosaic Retail and apportions no fee to Marquez.
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Matters are substantially related when they involve the same transaction or legal dispute or when there is a substantial overlap in factual and legal issues such that confidential information from the prior matter would normally have been revealed to the lawyer. Overlap in the same product, clinical trials, or contractual provisions often satisfies the test even if the new claims address later events.
Yes. A lawyer who changes firms may not represent a person in a substantially related matter adverse to a former client of the prior firm if the lawyer acquired material confidential information about that client unless the former client gives informed consent confirmed in writing. Screening and notice requirements may allow the new firm to proceed in some cases.
Information relating to the representation remains protected even after the matter concludes. The lawyer may not reveal or use that information to the former client's disadvantage unless the information has become generally known or the former client gives informed consent.