While traveling eastbound on the GCP I noticed a NYPD Highway Patrol car stilling on the shoulder right by the on-ramp from the Cross Island Parkway. Because I was heading eastbound I wasn't concerned since the LEO appeared to be tagging eastbound traffic. However, as I passed him I noticed he was shooting cars from behind!!! (Using PL3) He wasn't perpendicular to the road but instead was just slightly out to the left on the shoulder with his window down. We has aiming at cars that passed him (I guess people who were clueless his was out in the open). My only other thought was that maybe he was tagging traffic on my side, running a two car operation. However to get to the point, its it even legal for a LEO's to shoot rear lidar in NY??? If so I'm going to have to get LI's in the front/rear.