New York City, Los Angeles, Chicago and Las Vegas are among scores of police departments across the country quietly using a highly secretive technology developed for the military that can track the whereabouts of suspects by using the signals constantly emitted by their cellphones.
Civil liberties and privacy groups are increasingly raising objections to the suitcase-sized devices known as StingRays or cell site simulators that can sweep up cellphone data from an entire neighborhood by mimicking cell towers. Police can determine the location of a phone without the user even making a call or sending a text message. Some versions of the technology can even intercept texts and calls, or pull information stored on the phones.
At least 72 state and local law enforcement departments in 24 states plus 13 federal agencies use the devices, but further details are hard to come by because the departments that use them must take the unusual step of signing nondisclosure agreements overseen by the FBI.