John Gaal's Ethics Corner

A: Yes it does. Under DR 5-105, a lawyer is not to undertake, or continue in, employment on behalf of one client if it is likely to involve the lawyer in representing the differing interests of another client. As explained in ABA Formal Opinion 92-367, when a lawyer finds him- or herself having to cross examine a current client as an adverse witness, he or she is faced with exactly that type of dilemma. It does not matter whether the client is a fact witness or an expert witness, or whether the examination is at trial or in discovery. In either case, the lawyer's duty of loyalty to his client/witness precludes him or her from acting in such an adverse capacity.

A similar situation can arise when the adverse witness is a former rather than a current client. In that case, however, it is not the lawyer's duty of loyalty that creates the problem because that duty generally ends with the conclusion of the representation. Rather, it is the lawyer's duty to maintain client confidences and secrets, which continues even after the attorney client relationship has ended, which can create the problem. Where there is a substantial relationship between the current matter and the prior representation of the former client/witness, or confidential information acquired in the course of the prior representation of the former client/witness is potentially relevant in the new matter, DR 5-105 is likely to preclude the lawyer from similarly acting in an adverse manner to the former client/witness.