MBE Rules · Professional Responsibility

Duty to Former Client

Cal. Rules of Prof. Conduct 1.9

The rule

A lawyer who has formerly represented a client shall not represent another person in the same or a substantially related matter in which that person's interests are materially adverse to the former client, absent informed written consent from the former client. Confidentiality obligations survive termination.

In plain English

A lawyer cannot take on a new client if that client's interests conflict with those of a former client in a similar matter, unless the former client gives informed written consent. Even after the lawyer-client relationship ends, the obligation to keep the former client's information confidential continues.

Worked example

Attorney Smith previously represented Client A in a contract dispute. Now, Client B wants to hire Smith for a lawsuit against Client A regarding the same contract. Smith cannot represent Client B without getting written consent from Client A, as their interests are materially adverse.

Memory hook

Once a client, always a client—keep their secrets safe!

The trap

Exams may present scenarios where the former client’s interests seem only slightly related to the new matter, leading students to mistakenly believe consent is not required.

How examiners test it

Questions often involve fact patterns where a lawyer is approached by a new client with conflicting interests, testing the candidate's understanding of the duty to former clients and confidentiality.

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