Cal. Veh. Code § 2814
Every driver of a passenger vehicle shall stop and submit the vehicle to an inspection of the mechanical condition and equipment of the vehicle at any location where members of the California Highway Patrol are conducting tests and inspections of passenger vehicles and when signs are displayed requiring such stop.
The Commissioner of the California Highway Patrol may make and enforce regulations with respect to the issuance of stickers or other devices to be displayed upon passenger vehicles as evidence that the vehicles have been inspected and have been found to be in safe mechanical condition and equipped as required by this code and equipped with certified motor vehicle pollution control devices as required by Part 5 (commencing with Section 43000) of Division 26 of the Health and Safety Code which are correctly installed and in operating condition. Any sticker so issued shall be placed on the windshield within a seven-inch square as provided in Section 26708.
If, upon such inspection of a passenger vehicle, it is found to be in unsafe mechanical condition or not equipped as required by this code and the provisions of Part 5 (commencing with Section 43000) of Division 26 of the Health and Safety Code, the provisions of Article 2 (commencing with Section 40150) of Chapter 1 of Division 17 of this code shall apply.
The provisions of this section relating to motor vehicle pollution control devices apply to vehicles of the United States or its agencies, to the extent authorized by federal law.
Ca. Veh. Code § 2814