Police usually cannot impound the car for thirty days simply because an unlicensed driver received a traffic citation.  However, Arizona Law (ARS 28-3511) allows an officer to impound a car for thirty days if the driver's license of the driver was revoked for any reason or was suspended for DUI, or for too many driving points, or for driving on a revoked or suspended license. In those cases the officer can impound the car. The car can be released if the driver gets their license reinstated. The car can also be released to the spouse of the driver or to another owner under certain circumstances.