California Code, Code of Civil Procedure - CCP § 285.1

An attorney of record for any party in any civil action or proceeding for dissolution of marriage, legal separation, or for a declaration of void or voidable marriage, or for the support, maintenance or custody of minor children may withdraw at any time subsequent to the time when any judgment in such action or proceeding, other than an interlocutory judgment, becomes final, and prior to service upon him of pleadings or motion papers in any proceeding then pending in said cause, by filing a notice of withdrawal.  Such notice shall state (a) date of entry of final decree or judgment, (b) the last known address of such party, (c) that such attorney withdraws as attorney for such party.  A copy of such notice shall be mailed to such party at his last known address and shall be served upon the adverse party.