Originally Posted by KEVTEX

GPS jammers are for people who don't want to be tracked by someone else. Commercial vehicles are often tracked by GPS so the company knows where their vehicles are at any given time. Not all employees cooperate with the corporate surveilance. Some rental car companies charge big extra fees if the vehicle is taken out of state. I remember being warned about extra charges if the vehicle was taken out of state when I rented a car in Las Vegas.
For a GPS jammer to be legal it would have to operate under the FCC rules for radio transmitters. Even if these jammers are Part 15 devices(less than 100mw) I doubt transmitting on GPS frequencies is legal.