California Code, Code of Civil Procedure - CCP § 134

(a) Except as provided in subdivision (c), the courts shall be closed for the transaction of judicial business on judicial holidays for all but the following purposes:

(b) Injunctions and writs of prohibition may be issued and served on any day.

(c) In any superior court, one or more departments of the court may remain open and in session for the transaction of any business that may come before the department in the exercise of the civil or criminal jurisdiction of the court, or both, on a judicial holiday or at any hours of the day or night, or both, as the judges of the court prescribe.

(d) The fact that a court is open on a judicial holiday shall not make that day a nonholiday for purposes of computing the time required for the conduct of any proceeding nor for the performance of any act. Any paper lodged with the court at a time when the court is open pursuant to subdivision (c), shall be filed by the court on the next day that is not a judicial holiday, if the document meets appropriate criteria for filing.