A traffic stop is in violation of the Fourth Amendment when it is based upon an officer’s pure mistake of law because there is no objectively reasonable basis to believe that a violation of law occurred. A traffic stop was predicated on the lack of a front license plate on a vehicle with a Florida license plate on the rear. Vehicle Code section 5200, subdivision (a) provides that when two license plates are issued for use upon a vehicle, they shall be attached to the vehicle for which they are issued, one in the front and the other in the rear. When only one license plate is issued, it must be attached to the rear. (Veh. Code, sec. 5200, subd. (b).) Florida issues only one plate. If the officer does not know whether the state issues two plates, he is not authorized to stop the vehicle so that he can determine the status of the law from the detainee.