Nevertheless, several thousand are reportedly in use in Britain and more than 100,000 in the U.S., their main purpose being to defeat GPS tracking systems installed in trucks by their company owners.
Being active devices, these things must give themselves away to the right detection equipment.
In the US, the FCC should set up along highways and reel in the drivers who think they are being cute by using jammers to defeat their company's tracking devices. The better the enforcement and the higher the fines, the better the dis-incentive for using GPS jammers.