EC 4-2.

The obligation to protect confidences and secrets obviously does not preclude a lawyer from revealing information when his client consents after full disclosure, when necessary to perform his professional employment, when permitted by the Disciplinary Rules, or when required by law. Unless the client otherwise directs, a lawyer may disclose the affairs of his client to partners or associates of his firm. It is a matter of common knowledge that the normal operation of a law office exposes confidential professional information to non-lawyer employees of the office, particularly secretaries and those having access to the files; and this obligates a lawyer to exercise care in selecting and training his employees so that the sanctity of all confidences and secrets of his clients may be preserved. If the obligation extends to two or more clients as to the same information, a lawyer should obtain the permission of all before revealing the information. A lawyer must always be sensitive to the rights and wishes of his client and act scrupulously in the making of decisions which may involve the disclosure of information obtained in his professional relationship. Thus, in the absence of consent of his client after full disclosure, a lawyer should not associate another lawyer in the handling of a matter; nor should he, in the absence of consent, seek counsel from another lawyer if there is a reasonable possibility that the identity of the client or his confidences or secrets would be revealed to such lawyer. Both social amenities and professional duty should cause a lawyer to shun indiscreet conversations concerning his clients.