Cal. Code of Civil Procedure - CCP § 1297.291. Section 1297.291.
Unless otherwise agreed by the parties, in arbitral proceedings with more than one arbitrator, any decision of the arbitral tribunal shall be made by a majority of all of its members.
Notwithstanding this section, if authorized by the parties or all the members of the arbitral tribunal, questions of procedure may be decided by a presiding arbitrator.