Last week, the ACLU
was scheduled to meet with local police in Sarasota Florida to discuss the use of cell phone interception towers, dubbed stingrays, that are an increasingly common feature of federal and local investigations. A stingray
is a fake cell phone tower that law enforcement can configure to temporarily replace the real towers a device would normally connect to. In an astonishing turn of events, the US Marshals Service has acted to prevent the meeting from taking place -- seizing all of the relevant records and claiming that they're the property of the Marshals (and by extension, the US government).
Meanwhile, a Tallahassee judge reviewing a similar request for access to what ought to be public records has ordered the release of court transcripts
that show how the police use stingray towers. The transcript is available here -- it steps through how the police and Verizon cooperate to first isolate a particular device, force that device to connect to the stingray tower, and then trace that connection first to an apartment complex and then to a particular apartment. Stingray-connected devices can be forced to transmit at full power at all times, which drains the battery more quickly -- the police office being interviewed identifies this as a concern as it puts a time limit on how much time officers have to find the device. (In this particular case, the cell phone being traced had been stolen).
Q. Alright. And what exactly did you do to narrow it down, once you got to the apartment complex?
Why The Government Is Fighting To Keep This Information Secret
A. Again, using portable equipment, quite literally stood in front of every door and window measuring, determining that direction of where the signal was emanating from and contacting investigators, and advised them that we had an apartment.
What the court transcript reveals
is that the Tallahassee police can track any cell phone that's powered up, that it's used this capability more than 200x since 2007, and that the accuracy and success rate of the hardware is (according to the recollection of an officer that's worked in the department since 1995) 100%. It tracks a phone even if the phone isn't making or receiving calls, and police can essentially go door-to-door to achieve a lock on the target apartment.
Nobody likes giving up the details of such a highly effective program -- and that's why in Sarasota, the federal government is fighting back. According to the ACLU, it received information indicating that in Sarasota, the authorizations for collecting information via stingray were based on so-called "trap and trace," orders, which typically only capture phone call metadata -- not the entire activity of a cell phone (and potentially every other cell phone in the region). Before the ACLU could meet with the Sarasota Police Department and investigate the files in question, the US Marshals deputized a Sarasota officer and therefore declared the entire records of the affair sealed. Needless to say, the ACLU will be appealing that decision.