Paul Thurst at Engineering Radio analyzes the Federal Communications Enforcement Advisory No. 2012-02, about jamming devices for Cellphones, GPS and WiFi which specifies fines in excess of $100,000 per incident. The advisory said:

"In recent days, there have been various press reports about commuters using cell phone jammers to create a “quiet zone” on buses or trains. We caution consumers that it is against the law to use a cell or GPS jammer or any other type of device that blocks, jams or interferes with authorized communications, as well as to import, advertise, sell, or ship such a device. The FCC Enforcement Bureau has a zero tolerance policy in this area and will take aggressive action against violators."

Thurst considers how most GPS jammers are being used: as privacy protection devices. "That set of people can range from truckers who don’t what their bosses to know every aspect of their journey, citizens concerned about GPS tracking devices on their vehicles, or ordinary people who don’t want the phone company tracking their every move via GPS enabled cellphones," he writes. He also notes that there's plenty of interference for the FCC to worry about: IBOC to analog adjacent channels, broadband over power line, electrical noise on the medium wave band, illegal 2 way radios on RPU frequencies, etc. "Of course, there is no money in those issues," he observes. He notes that the FCC isn't going to catch many truckers going 70 mph across interstate highways using small jamming devices. "Perhaps if the technology wasn’t so pervasive and readily abused by certain corporate and government entities, the desire to jam it wouldn’t exist," he concludes. Read the full story at Engineering Radio.