Mobile phone tracking scrutinized.

• Position: UP FRONT: News, Trends & Analysis

Nearly 200 million Americans have cell phones, but many of them are not aware that wireless technology companies, as well as the U.S. government, track their movements through signals emitted by their handsets.

Cellular providers, including Verizon Wireless and Cingular Wireless, know, within about 300 yards, the location of their subscribers whenever a phone is turned on. Even if the phone is not in use, it still communicates with cell tower sites, and the wireless provider keeps track of the phone's position as it travels. These companies are marketing services that turn handsets into even more precise global positioning devices for driving or allowing parents to track the whereabouts of their children.

[ILLUSTRATION OMITTED]

In recent years, law enforcement officials have used cellular technology as a tool for easily and secretly monitoring the movements of suspects. But this kind of surveillance, which investigators have been able to conduct with easily obtained court orders, has now come under tougher legal scrutiny.

The New York Times reports that, in the last four months of 2005, three federal judges denied prosecutors the right to get cell phone tracking information from wireless companies without first showing "probable cause" that a crime has been or is being committed--the same standard applied to requests for search warrants.

The rulings, issued by magistrate judges in New York, Texas, and Maryland, underscore the growing debate over privacy rights and government surveillance in the digital age. Wireless providers keep cell phone location records for varying lengths of time, from several months to years, and have said that they turn over cell location information when presented with a court order to do so.

Prosecutors argue that having such data is crucial to finding suspects, corroborating their whereabouts with witness accounts, or helping build a case for a wiretap on the phone. The government has routinely used records of cell phone calls and caller locations to show where a suspect was at a particular time, with access to those records obtainable under a lower legal standard.

But it is unclear how often prosecutors have asked courts for the right to obtain cell-tracking data as a suspect is...