Fifth Gear
I was watching Fifth Gear on Channel 5 tonight (mainly to letch at Vicki Butler-Henderson). They had a very good feature on anti-speed cam protection measures. All the passive detectors were judged by a tame copper as being legal as all they do is provide information, but the active laser emitter, although very effective, was not. Said tame copper explained that the laser emitter disrupts due legal process and would result in the driver having to explain to a court why he had it fitted to his vehicle.
Top tip, Fifth Gear are running a competition to win the Volvo they fitted all of the legal gadgets to. If you call 09015 33 99 55 and tell them that the answer is (a. GPS) you may win the motor with the toys. Good luck!