not sure
I'm no lawyer but I know that cops enter notes during a stop which are brought up on the computer when you go to see a hearing officer. (first step in MN). I've had a ticket thrown out by a hearing officer because it was something unrelated to the stop and couldn't be given because of the reason for the stop. The hearing officer even called down to the precinct and explained to them they should get their rookies in order! I was really surprised, she threw out the original one too just for my hassle.
Relating to your question - I believe that if they stopped you for something which actually wasn't wrong, then all other infractions written from that stop would be illegal. Kind of like illegal search and seizure. Those who say the cops will just make something else up in court must hate cops, it won't happen. The reason for the stop is already in the computer. Of course, it might be something else which you are unaware of. You can subpoena the notes if you go far enough. I attribute this to the same fact that a cop can't pull you over for no reason. If they could just make one up and say, "oh, look at that... your tail light isn't broken after all," but write you a ticket for some other reason inside of your car, or find a dead body in the trunk it would be illegal search and seizure. Won't hold in court.
Just be nice with the hearing office, know the facts, and don't play lawyer and you should do just fine. Go early or you'll have a long wait in Hennepin county anyways. Be there by 740 for the 8am opening.