I am a law school graduate. What I offer is mere information, not to be construed as forming an attorney client relationship.
From Traffic Law, located under General Practice at the freeadvice.com homepage:
DOES A SPEEDING MOTORIST HAVE THE RIGHT TO SEE THE RADAR GUN?
You have a right to see the gun and to see the basis for which the cop is stopping you. You'll need to do some work, but you can also subpoena the calibration records for the gun. In California, for example, if it wasnt calibrated within the last 10 days of your stop, you win.