California Code, Code of Civil Procedure - CCP § 116.370

(1) If the court determines that the action was not commenced in the proper venue, the court, on its own motion, shall dismiss the action without prejudice, unless all defendants are present and agree that the action may be heard.If the court determines that the action was not commenced in the proper court location, the court may transfer the action to a proper location pursuant to local rule.

(2) If the court determines that the action was commenced in the proper venue and court location, the court may hear the case if all parties are present. If the defendant challenged venue or court location and all parties are not present, the court shall postpone the hearing for at least 15 days and shall notify all parties by mail of the court's decision and the new hearing date, time, and place.