Was it Radar or Laser?
There has to be calibration records indicating when he checked the calibration of the radar and when the radar was calibrated. He should have a log of when he checked it. Probably written on his copy of the ticket. He should have a certificate that he's certified, records of when he checked the calibration, records of when the unit was actually calibrated by a tech, records for the certification of the tuning forks. When were the tuning forks last checked? Was it stationary radar or moving? Probably stationary. If it was moving then you have to have the certificate for the speedometer showing it's calibrated. When running moving radar the radar sends out two signals. One picks up the ground speed and one picks up the closing object speed. The ground speed displays as the patrol speed. The counting unit of the radar deducts his ground/patrol speed to the closing speed to give him your speed. His ground speed has to match the speed on his certified speedometer. If he's moving too slow the radar can screw up only and show the combined speed in the target window. This is why it's difficult to run moving radar driving through a school zone. You can tell though by the patrol speed readout. Also, if he was too close to the back of a large vehicle in front of him going down a highway, the radar could be geting it's ground speed from the back of that vehicle. If he's doing 55 and the truck was doing 50, it could get a false reading of 5 mph from his closing speed to the vehicle and add the remaining 50 mph to you.
If he was on a motorcycle he was probably stationary which has fewer errors to watch for. Any large neon signs around him? They say it can cause errors, but I've never seen it. Some talk about the angle of his radar to you if he's on the side of the road. Actually, anything other than straight on reduces the target speed (slightly).
Basically my advise is:
1) Go to court. There is a small chance he won't show to get paid his minimum contractural overtime (probably atleast 3 hours even if he's there 1).
2) Ask for certificates for the operator (cop), radar, tuning forks and record of calibration. You'd be surprised at how many departments don't keep good records, can't afford maintenance or proper training of their officers.
3) Don't admit to anything over the speed limit. If he says 52 and you say you were doing no more than 40, the judge will find you guilty of doing 40 in a 35.
4) Stay away from discussing speed, tire sizes and what you think your speedometer really means. The court will eat you alive.
5) The prosecutor will eventually want to talk to you. Tell him/her that your truck is a POS that doesn't run that well, you know you weren't going that fast and complain about getting points on your license and a big fine. The prosecutor may offer you a no point violation and reduced fine to clear the docket and keep from going to court. The cop will agree to it because he hates testifying and he's getting more overtime than what he's actually working. See #1 above.
6) Unless you lose time from work, it's not going to cost you anymore to go to court.
The cop is required to:
Explain the calibration check, when it was done and the operation of the radar.
Visual identification of your vehicle and visual estimation of your speed
Confirm his estimation by the use of radar
Maintain a tracking history until you pass him to ensure he was clocking you and not someone behind you.
I doubt you'll win unless it's a cop with a bad rep with the court or completely unprepared. Your best bet is to hope for a deal on something lesser to avoid a trial. Judge would probably rather be playing solitare on his computer at the bench or leaving early because nothing is left on the docket.
Good luck.
oh...one last thought for whoever....
If a cop stops you for speed from moving radar, look at the radar. There should be two speeds. One for his, one for yours. Radars have a feature to shut off the display for the 'patrol' speed and only show the 'target' speed. Have them turn it back on if your only shown one speed from moving radar. He probably blocked it so you wouldn't see he was speeding too.
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