EC 4-4.

The attorney-client privilege is more limited than the ethical obligation of a lawyer to guard the confidences and secrets of his client. This ethical precept, unlike the evidentiary privilege, exists without regard to the nature or source of information or the fact that others share the knowledge. A lawyer should endeavor to act in a manner which preserves the evidentiary privilege; for example, he should avoid professional discussions in the presence of persons to who the privilege does not extend. A lawyer owes an obligation to advise the client of the attorney-client privilege and timely to assert the privilege unless it is waived by the client.