California Code, Family Code - FAM § 6300

(a) An order may be issued under this part to restrain any person for the purpose specified in Section 6220, if an affidavit or testimony and any additional information provided to the court pursuant to Section 6306, shows, to the satisfaction of the court, reasonable proof of a past act or acts of abuse. The court may issue an order under this part based solely on the affidavit or testimony of the person requesting the restraining order.

(b) An ex parte restraining order issued pursuant to Article 1 (commencing with Section 6320) shall not be denied solely because the other party was not provided with notice.