In Utah the year is the only one that changes color, all of the months are white. That's why I was looking at his plates, to see if I could see even the letters on his plate. Granted I'm not a trained observer of registration violations and maybe it was observable to someone who is. Given the distance and the visibility during the night I'm pretty skeptical. It's just a sneaking suspicion I've had - because I know I'd want to use those license plate readers in exactly that why if I was in their place.