I know some will argue this, but by law driving is a privilege, NOT a right.
You are required to get a license from the state, & they can take it away from you.
And lock you up if you don't have one.
If a cop follows you long enough, he can find a reason to pull you over. Failure to signal lane change, not turning into the nearest lane provided for your direction of travel, no license plate light, ad nauseum.
Once he's got you pulled over, he can use anything he can see without physically entering your vehicle as a reason to investigate further.
Screw up, & they take away your driving privilege.
Eric
CBVET