Can the FBI Secretly Track Your Cell Phone?

Michael Isikoff

The Justice Department is poised this week to publicly defend a little-known law-enforcement practice that critics say may be the "sleeper" privacy issue of the 21st century: the collection of cell-phone "tracking" records that identify the physical locations where the phones have been.

It may come as a surprise to most of the owners of the country's 277 million cell phones, but their cell-phone company retains records of where their device has been at all times—either because the phones have tiny GPS devices embedded inside or because each phone call is routed through towers that can be used to pinpoint the phones' location to within areas as small as a few hundred feet.