Does attorney-client privilege apply to disclose the identity of an anonymous client?

Generally, the identity of an attorney's client is not considered within the protection of the attorney-client privilege. (People v. Chapman (1984) 36 Cal.3d 98, 110; Hays v. Wood (1979) 25 Cal.3d 772, 785.) There is a recognized exception to this rule, however, where known facts concerning an attorney's representation of an anonymous client are such that the disclosure of the client's identity would implicate the client in unlawful activities, thus exposing the client to potential investigative action or criminal or civil liability. (See Hays v. Wood, supra, 25 Cal.3d 772, and cases cited therein.)