Fear of being tracked leads citizens to consider buying GPS jammers

　　With the rapid proliferation of inexpensive, fast, accurate, and small, easy-to-use vehicle tracking systems, law enforcement agencies at all levels are using GPS-assisted devices to covertly monitor suspects.

　　Since then, case by case has helped determine the scope of searches and seizures, the necessary details of search warrants, and where and when U.S. residents can get privacy.

　　Generally, U.S. court decisions reaffirm that your home is still your castle. A castle includes a fenced yard, courtyard, or other area attached to your house, and you have every right to think that you will not be bugged or watched.

　　When the Fourth Amendment to the U.S. Constitution was ratified, it did seem to be sufficient for the times. New Americans were tired of the free search and pillage of colonial powers, and general search warrants were as flawed as Swiss cheese.

　　The Founding Fathers said authorities must either ignore it or obtain a specific search warrant detailing what they hope to find and where they hope to find it. They cannot knock on citizens' doors on a whim, but need to provide evidence of "probable cause" to the judge who decides whether to allow the search.

　　Court decisions expand police powers in these cases and address the use of technology. But technology is changing so fast, the law is still struggling to catch up.

　　With satellite positioning, thermal imaging, satellite photos and wireless, navigation and timing technologies, as well as smartphones and other mobile devices, violations of privacy are now much less common and imperceptible than before. Privacy concerns have been raised for GPS-enabled social networking tools (such as Facebook Places or FourSquare) or visualization and navigation-related services (such as Google Earth or MapQuest).

　　Worry about being tracked — whether by the FBI or the Public Toll Highway Administration — monitoring payments, being stalked by suspicious spouses — could lead some citizens to consider buying GPS jammers, which could cause widespread problems of its own.

　　Those concerns are emerging in a growing number of federal appeals court cases across the country in which GPS or other tracking technologies are at play.