The FBI requires state and local police to keep quiet about the capabilities of controversial surveillance gear that allows law enforcement to eavesdrop on cellphone calls and track individual people based on the signals emitted by their mobile devices, says an FBI document released under a Freedom of Information Act request and reported by the Washington Post. The 2012 document is a heavily redacted letter between the FBI and police in Tacoma, Wa., which sought to acquire an “IMSI catcher,” sometimes described as a “fake cellphone tower” because it tricks individual phones into routing their calls and other data through the surveillance equipment.
The Tacoma police were buying gear produced by Harris Corp., a Florida-based company that makes the StingRay and other IMSI catchers used by law enforcement agencies across the U.S. The FBI letter, designated as “law enforcement sensitive,” told the Tacoma police chief that the Federal Communications Commission authorizes the sale of such surveillance equipment to state and local police departments on the condition that they first sign an FBI “non-disclosure agreement.” The details of the agreement are redacted from the letter as released. It was published first by MuckRock, a news site that helps journalists, researchers and others submit Freedom of Information Act requests and publishes the results.