Driving is a privilege not a right, hence why you must have a license to drive legally. The police are allowed to pull you over for any reason, if upon pulling you over they have reason to believe you are under the influence of alcohol or drugs they will ask your permission to do a sobriety test or B.A.C test. If you pass it you are good to go, no harm no foul! If you fail then frankly you shouldn't be driving, and hence you are screwed! Lets not bunk up the system with more red tape!!! Keep it simple