In a major decision last week, the Fifth Circuit Court of Appeals ruled that the location of your cell phone when you place a call is not protected by the Fourth Amendment, which guards against “unreasonable searches and seizures.”
Whenever you make a cell-phone call, your phone provider knows where you are—it needs that information in order to find your device and complete the call. Phone companies generally keep records of users’ locations when calls are connected and disconnected. These logs, which store data about which cellular sites phones connect to, are known as historical cell-site records. Since most people keep their cell phones with them, a record of a phone’s location generally provides a good lead on its owner’s location as well. If the Feds want to know where you were last Tuesday at 9 P.M., for example, they can get a pretty good idea by finding out where your phone was.
The important legal question is how much protection these records receive when the government wants to make providers turn them over. In other words, what kind of evidence should the government be required to present in order to get your location records from a cell-phone company?
For the rest of the story: http://www.newyorker.com/online/blogs/elements/2013/08/why-your-cell-phones-location-isnt-protected-by-the-fourth-amendment.html