Not if you carry a GPS with the track feature enabled
I doubt whether that would be admissible in court. It's dead easy to import the track in, say, OziExplorer, modify the altitudes and then export it again into the GPS.
Unless you have a sealed, tamperproof model (like the ones gliders use to record their achievements) and follow proper chain-of-evidence procedures, my guess is that the prosecutor would have no problem throwing this "evidence" out.
Apart from the fact that GPS isn't all that accurate in the vertical and if you want to argue that you flew at 501' instead of 499', your GPS is not going to help you.