Where two or more clients have retained or consulted a lawyer upon a matter of common interest, none of them, nor the successor in interest of any of them, may claim a privilege under this article as to a communication made in the course of that relationship when such communication is offered in a civil proceeding between one of such clients (or his successor in interest) and another of such clients (or his successor in interest).

(Enacted by Stats. 1965, Ch. 299.)