Alright, here's my $.02 on electronic warfare.
Active jammers are illegal. As they transmit radio frequencies they are regulated by the FCC and any transmission with the intent of interfering with the operation of other electronic equipment is prohibited. Believe me, the military even has a hard time getting clearance to practice using its jamming equipment. That being said, if you decide to get one of the available black market active jammers (such as the Phantom--NOT the same one that's sold by Rocky Mountain), just be aware that their effectiveness is very limited, due to low power output. The jammer has a small window in which it is effective. Too close and radar gun burns through, too far away and your transmitter is too weak to jam the gun.
Passive jammers are legal as they don't transmit any radio signals, but they are good for jamming tuning forks, not radar guns. They claim to work by adding a chirp to the signal...sorta like a vibrating mirror, so that you get a fuzzy return, but on one magazine review, a Rocky Mountain Radar product actually increased the range at which its speed was detected.
LIDAR or laser jammers are legal in most areas as the FCC does regulate the transmission of light. You'll have to refer to local laws on those as well as passive jammers. Laser jammers from all the reviews I've seen are very effective. However, it's a little known fact that driving with your high beams on also blinds the laser and gave the same results in most tests.
My advice, keep your eyes wide open and don't drive stupid.
Bill
[This message has been edited by wildbill846 (edited 04 May 2002).]