Well, in this day and age, cameras can be very small and concealed. Photograph the cops without them knowing they’re being photographed.
If they see you with a camera, then you’re most likely screwed.
The only thing that REALLY works is a clear resin spray. You spray a coat or two on the front and back plates, and re-install them on your car. It will look NORMAL to the naked eye, but the camera sees only pure GLARE when a picture is taken. $25 per can. Google it on the internet.