Previously, we explained that “Stingrays,” a.k.a. cell site simulators, are powerful law enforcement tools that allow police to track mobile phone users’ location and sometimes intercept their data transmissions. We also noted that in some cases, police have used Stingrays to track suspects without a warrant.

Fortunately, judges are beginning to crack down on such operations. Defense attorneys for Kerron Andrews, a Baltimore man charged with attempted murder in 2014, discovered he had been located via the warrantless use of a cell site simulator. In March, the Maryland Court of Special Appeals threw out all evidence in the case gathered with the device, in what is possibly the first appellate decision concerning the use of Stingrays. Further prosecution of the case may be impossible.

Hoping to build on that ruling, the American Civil Liberties Union and the Electronic Frontier Foundation investigated the circumstances surrounding the arrest of Milwaukee man Damian Patrick. In response to an amicus brief the two organizations filed recently, the government admitted that the Milwaukee P.D. used a Stingray without a warrant to locate Patrick. The police first told Patrick that an anonymous source had told them of his whereabouts and later implied the information came from his service provider, Sprint.

In 2014, police used a cell site simulator to locate murder suspect Robert Copes at his apartment home and discovered the blood of the murder victim in the apartment. On April 25, 2016, Circuit Judge Yolanda Tanner reluctantly threw out that evidence because police had not obtained a search warrant, despite having court permission to use the Stingray.

Clearly, judges are quite concerned about the pitfalls of widespread use of cell site simulators, and if police want to avoid jeopardizing prosecutions, they must be very careful to obtain proper permission before using them.