The Detroit News has a story on special infrared transmitters that can can broadcast a signal to receivers on traffic lights, turning the light from red to green (Gadget may wreak traffic havoc). The purpose of the devices is to ease the way for emergency vehicles. However, now civilian knock offs are being sold, allowing the average citizen to clear their own traffic path. The traffic headaches this can cause will be enormous, not to mention the problems it will cause for emergency vehicles. The consumer devices themselves are probably legal to sell currently.

Educated Guesswork notes how easily this could have been prevented with some simple cryptography (Remote traffic light control).

Ed Felten notes how poor engineering practices might result in poor law: banning transmitters and thus creating a black market (Remote Controls for Traffic Lights).