California Code, Penal Code - PEN § 816a

A summons issued pursuant to Section 813 shall be served by any peace officer, or any public officer or employee authorized to serve process when the summons is for a violation of a statute or ordinance which that person has the duty to enforce, within the state. Upon service of the summons, the officer or employee shall deliver one copy of the summons to the defendant and shall file a duplicate copy with the magistrate before whom the defendant is to appear.