I don't know much about photo enforcement, so I'm assuming a picture of your license plate is used to "identify" you.
I think most camera systems are sensitive to near IR. Seems like you could put enought high luminus intensity IR LEDs aound your license plate to effectively overexpose any attempt to photograph your plate. Maybe gut an old ZR3 laser jammer, or simply buy enough IR LEDs from Radio shack. No need to try and detect or emit any special jamming sequence. Just leave the IR LEDs on all the time when your car is running.
Any feedback on this idea?