The vehicle code alone for my state is nearly three inches thick. If they want to pull you over, you will almost certainly give them a "valid" reason if they follow you for even just a few minutes. A friend of mine in law enforcement demonstrated this to me once while riding in my car. He had racked up four or five things on the car ahead of us (tailgating, crossing the fog line or center barrier, failure to signal within x yards of a turn, etc.) in under a mile.