Law enforcement is more and more deploying International Mobile Subscriber Identity locators that masquerade as cell towers and enable government agents to suck down data from thousands of subscribers as they hunt for an individual’s cell signal. 

This “Stingray” technology can detect and precisely triangulate cellphone signals with an accuracy of up to 6 feet—even inside your house or office where warrants have been traditionally required for a legal police search.

Law enforcement agencies prefer not to talk about cellphone tracking. “Never disclose to the media these techniques—especially cell tower tracking,” advises a guide for the Irvine, California, police department unearthed by the ACLU in 2012. The Iowa Fusion Center, one of 72 local law enforcement intelligence agencies established in coordination with the Department of Homeland Security, distributes a training manual that warns, “Do not mention to the public or media the use of cellphone technology or equipment to locate the targeted subject.” 

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This pervasive secrecy means police surveillance is rarely challenged because

 1) law-abiding citizens never learn that they have been targeted, since their service providers are not allowed to tell them; 

2) court orders authorizing surveillance are sealed and never made public; and 

3) the public and Congress do not have access to systematic data on how often electronic surveillance is used. 

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Many local police departments have policies that are looser and more inconsistent than the Justice Department’s: Based on information from 230 law enforcement agencies around the country, the ACLU found that nearly all of the police departments acknowledged tracking cellphones, but “only a tiny minority reported consistently obtaining a warrant and demonstrating probable cause to do so.”

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 Ubiquitous surveillance becomes indistinguishable from totalitarianism. “The ultimate check on government as a whole is its inability to know everything about those it governs,” Keizer writes in Privacy.

The Digital Due Process Coalition Web Site