An electronic device that tricks cellphones into revealing a user's location is becoming a key weapon for law enforcement in its battle against drug traffickers, terror suspects and other dangerous criminals -- but its potential misuse against innocent Americans and the secrecy surrounding which agencies have the devices is of growing concern by civil liberties watchdogs and lawmakers.
Cellular site simulators — known as "StingRay tracking" — basically are fake cell towers that use digital signals to trick a cellphone into revealing its location and other information. Law enforcement typically places the device near the location of a known suspect -- but they also have been used at large gatherings such as rallies, where the digital information of hundreds, even thousands, is scooped up.
And while law enforcement agencies turn to the courts for permission to deploy the devices, the requests typically are generic applications called "pen register applications," which only require the agency to affirm that the device will be used in a criminal investigation, without having to name a specific individual. That legal vagueness is what concerns lawmakers.
"If you can track somebody’s location 24/7, you know the content of their life," said Rep. Jason Chaffetz, R-Utah. "I think innocent Americans have a reasonable expectation of privacy."
Chaffetz last November proposed the Stingray Privacy Act, which would toughen the warrants needed to deploy the devices and make their use without a court order illegal and punishable with a fine or up to 10 years in prison.
Since introducing the bipartisan legislation, Chaffetz said his ongoing investigation into which agencies use StingRay devices and why has yielded few answers.
"It’s still highly secretive," Chaffetz told FoxNews.com Wednesday. "They’re not very candid about how they’re using them."
"For instance, the IRS has this technology," he said. "What in the world are they doing with it? It raises questions as to why they would need to track people as they move around the country."
Cell site simulators are currently used by 13 federal agencies, including the U.S. Marshals Service and Drug Enforcement Administration, and at least 50 local and state police departments, according to the American Civil Liberties Union.
Places where the devices are used by local and state police include California, Texas, Minnesota, Florida, Maryland and New York.
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