I used to put my plate on my window because my license plate holes were shaved on my bumper and when I got pulled over, the cop told me about the whole "projectile" thing and that it could decapitate me if I was to get in an accident. After that, I just kept the front plate under my seat and I never got pulled over again for it. Keeping it on the window like flo w fx said makes it stick out like a sore thumb and gives them a reason to pull you.