"Absent a search warrant, the government may not turn a citizen's cell phone into a tracking device," Pauley wrote.
In September 2015, the Justice Department changed their policy to require agents to obtain a warrant before using the invasive device.
In March, a Maryland appeals court became the first state court to suppress evidence obtained through the use of a Stingray, a device manufactured by the Florida-based Harris Corporation, a US defense contractor. Following their ruling, the court published a 73-page explanation containing scathing commentary regarding Baltimore police failing to notify courts when using the surveillance device, and why police must obtain a warrant before using a Stingray.
“We conclude that people have a reasonable expectation that their cell phones will not be used as real-time tracking devices by law enforcement, and—recognizing that the Fourth Amendment protects people and not simply areas—that people have an objectively reasonable expectation of privacy in real-time cell phone location information. Thus, we hold that the use of a cell site simulator requires a valid search warrant, or an order satisfying the constitutional requisites of a warrant, unless an established exception to the warrant requirement applies,” the report read.
Critics of the Stingray, including the American Civil Liberties Union, have long argued that their use violates the US Constitution, as well as pointing out that the clumsy device is akin to using a 1000-meter net to catch a butterfly. When used, a Stingray can only indiscriminately collect data from every phone in the vicinity, regardless of a user’s relevance to the case.