California Code, Government Code - GOV § 68081

Before the Supreme Court, a court of appeal, or the appellate division of a superior court renders a decision in a proceeding other than a summary denial of a petition for an extraordinary writ, based upon an issue which was not proposed or briefed by any party to the proceeding, the court shall afford the parties an opportunity to present their views on the matter through supplemental briefing. If the court fails to afford that opportunity, a rehearing shall be ordered upon timely petition of any party.