Cal. Veh. Code § 31612
Persons operating vehicles, or combinations of vehicles, in the transportation of explosives and subject to this division, shall not accept any explosives for transportation unless the shipment is accompanied by a bill of lading or other shipping paper supplied by the shipper, showing the kind of explosives and bearing a statement that they have been packaged, labeled and marked in accordance with regulations of the United States Department of Transportation, and the bill of lading or other shipping paper shall be carried in the vehicle while en route and shall be displayed upon demand of any member of the California Highway Patrol or any police officer of a city who is on duty for the exclusive or main purpose of enforcing the provisions of this code.
Ca. Veh. Code § 31612