Well I read on GW white zombie's guitarists column and he said that in the court thay wouldn't take it because it is possible that you can cheat with that. As the guy said: "Remember your report card?" :D
What I have thought of is making a video in which you show a place which shows the date and time, kind of like Big Ben, and at the same time you play yor stuff on a tape before the camera.
What do you think about that?
Sound engeneers, do you think one can cheat with this method?