California Code, Code of Civil Procedure - CCP § 1297.41

A party who knows that any provision of this title, or any requirement under the arbitration agreement, has not been complied with and yet proceeds with the arbitration without stating his or her objection to noncompliance without undue delay or, if a time limit is provided for stating that objection, within that period of time, shall be deemed to have waived his right to object.