California Code, Probate Code - PROB § 2405

(a) Enter into an agreement in writing with the third person to refer the dispute to a temporary judge designated in the agreement. The agreement shall be filed with the clerk, who shall thereupon, with the approval of the court, enter an order referring the matter to the designated person. The temporary judge shall proceed promptly to hear and determine the matter in controversy by summary procedure, without any pleadings, discovery, or jury trial. The decision of the temporary judge is subject to Section 632 of the Code of Civil Procedure. Judgment shall be entered on the decision and is as valid and effective as if rendered by a judge of the court in an action against the guardian or conservator or the third person commenced by ordinary process.

(b) Enter into an agreement in writing with the third person that a judge of the court, pursuant to the agreement and with the written consent of the judge, both filed with the clerk within the time for bringing an independent action on the matter in dispute, may hear and determine the dispute pursuant to the procedure provided in subdivision (a).