Which party's consent is crucial when taking on a case representation against a former client?

When representing a new client in a matter that is directly adverse to a former client, the former client's consent is essential to comply with the ethical obligations outlined in the Model Rules of Professional Conduct. The duty of confidentiality and loyalty owed to a former client persists even after the representation has ended. Specifically, Rule 1.9 of the Model Rules addresses the duties owed to former clients, emphasizing that a lawyer must not represent anyone in a matter that is substantially related to the prior representation unless the former client provides informed consent.

This requirement aims to protect the former client's confidential information and to maintain trust in the attorney-client relationship. The aspect of consent means that the former client must be fully informed of the situation and must agree to the new representation. Without this consent, the attorney risks breaching professional conduct rules, which could lead to disciplinary actions or disqualification from the new case.

Other parties' consents, such as that of the new client or the attorney themselves, do not supersede the need for the former client's consent in these circumstances. The focus on the former client's interaction ensures protection of sensitive information that may be relevant to the new case being taken on by the attorney.