Every attorney who, having prosecuted or in any manner aided or promoted any action or proceeding in any court, as district attorney or other public prosecutor, afterward, directly or indirectly, advises in relation to, or takes any part in the defense thereof, as attorney or otherwise, or takes or receives any valuable consideration from or on behalf of any defendant therein, upon any understanding or agreement whatever, express or implied, having relation to the defense thereof, is guilty of a misdemeanor; and in addition to the punishment prescribed therefor he shall forfeit his license to practice.