California Code, Vehicle Code - VEH § 4460

(a) The Department of Motor Vehicles, the Traffic Adjudication Board, and the Department of the California Highway Patrol, any regularly employed and salaried police officer or deputy sheriff or any reserve police officer or reserve deputy sheriff listed in Section 830.6 of the Penal Code may take possession of any certificate, card, placard, permit, license, or license plate issued under this code, upon expiration, revocation, cancellation, or suspension thereof or which is fictitious or which has been unlawfully or erroneously issued. Any license plate which is not attached to the vehicle for which issued, when and in the manner required under this code, may be seized, and attachment to the proper vehicle may be made or required.

(b) Any document, placard, or license plate seized shall be delivered to the Department of Motor Vehicles.