OP - are you a dork? GO back up there and see if there is a no u-turn sign. Sheesh. ALSO make sure that it's reflective (can be seen at night) and is within a reasonable distance to the spot you turned. You don't go to court to "fight" a ticket w/out doing YOUR part to "fight" the ticket. If you'r enot gonan do your part then just pay the bitch.