California Code, Vehicle Code - VEH § 2814.2

(a) A driver of a motor vehicle shall stop and submit to a sobriety checkpoint inspection conducted by a law enforcement agency when signs and displays are posted requiring that stop.

(b) Notwithstanding Section 14602.6 or 14607.6 , a peace officer or any other authorized person shall not cause the impoundment of a vehicle at a sobriety checkpoint if the driver's only offense is a violation of Section 12500 .

(c) During the conduct of a sobriety checkpoint, if the law enforcement officer encounters a driver who is in violation of Section 12500 , the law enforcement officer shall make a reasonable attempt to identify the registered owner of the vehicle.  If the registered owner is present, or the officer is able to identify the registered owner and obtain the registered owner's authorization to release the motor vehicle to a licensed driver by the end of the checkpoint, the vehicle shall be released to either the registered owner of the vehicle if he or she is a licensed driver or to the licensed driver authorized by the registered owner of the vehicle.  If a notice to appear is issued, the name and driver's license number of the licensed driver to whom the vehicle was released pursuant to this subdivision shall be listed on the officer's copy of the notice to appear issued to the unlicensed driver.  When a vehicle cannot be released, the vehicle shall be removed pursuant to subdivision (p) of Section 22651 , whether a notice to appear has been issued or not.