Lawyer’s Duties when Client Revokes Consent to Conflict
Opinion rules that a lawyer is not required to withdraw from representing one client if the other client revokes consent without good reason and an evaluation of the factors set out in comment  to Rule 1.7 and the Restatement (Third) of the Law Governing Lawyers indicates continued representation is favored.
May a lawyer rely on a written waiver of conflict regarding the matter at hand signed, with informed consent, by two or more parties, after a subsequent, unforeseen falling out among those parties? (So that the lawyer is not required to relinquish representation of a long-term client/party to the original waiver due to one of the other party/signees revoking the waiver and objecting to the lawyer's continuing to represent the long-term client.
Pursuant to Rule 1.7 comment , a client who has given consent to a conflict may revoke the consent at any time. According to comment , whether one client's revocation of consent to his own representation precludes the lawyer from continuing to represent the other client depends on the nature of the conflict, whether the client revoked consent because of a material change in circumstances, the reasonable expectations of the other client, and whether material detriment to the other client or the lawyer would result.
The Restatement of the Law Governing Lawyers indicates that if one client revokes his consent to representation without good reason, the lawyer may continue representing the other client in the matter if the lawyer and other client have already relied on the consent to their detriment. The Restatement provides that a joint client may be justified in revoking consent to multiple representation when a material change occurs in the factual basis on which the client originally gave informed consent, such as when the clients develop antagonistic positions; the lawyer favors the other client; or the other client takes harmful action. Restatement (Third) of the Law Governing Lawyers §122 cmt. f (2000). Examples of detrimental reliance by the non-revoking client or the lawyer include the investment of substantial time and money in the representation; the disclosure of confidential information; the development of a relationship of trust and confidence between the lawyer and the non-revoking client; and the election by the lawyer or the non-revoking client to forego other opportunities in reliance on the consent.
The consent agreement may specify the effect of one client's repudiation upon the other client's right to continued representation and the lawyer's right to continue to represent the other client. The DC Bar suggests the following language:
You have the right to repudiate this waiver should you later decide that it is no longer in your interest. Should the conflict addressed by the waiver be in existence or contemplated at that time, however, and should we or the other client(s) involved have acted in reliance on the waiver, we will have the right--and possibly the duty, under the applicable rules of professional conduct--to withdraw from representing you and (if permitted by such rules) to continue representing the other involved client(s) even though the other representation may be adverse to you.
DC Bar Legal Ethics Committee Opinion 317 (2002).
In the absence of specific language in the consent agreement addressing the effects of repudiation, a lawyer is not required to withdraw from representing one client if the other client revokes consent without good reason and an evaluation of the factors set out in comment  and the Restatement favors continued representation.