In November 2014, Prince Jones was convicted for rape and robbery. To apprehend Mr. Jones, police used a “StingRay,” a device that captures a cellphone’s signal and measures the time it takes to communicate with the cellphone. In other words, a StingRay shouts “Marco,” and the cellphone responds with “Polo!” Based on these responses, a StingRay can discern the cellphone user’s location with great accuracy. The police did not have a search warrant authorizing them to use the StingRay for this purpose, but Mr. Jones’s motion to suppress the evidence obtained by the StingRay was denied.
Mr. Jones appealed, and in February 2016, we filed an amicus brief in this case in the D.C. Court of Appeals. In our view, a warrant should be required because, like turning a person’s car into a tracking device by attaching a GPS, a StingRay turns a person’s phone into a tracking device, and it does so by seizing locational information from him, not from the phone company. Additionally, a warrant should be required because cell site simulators interact with the cell phones of other people in the vicinity, forcing their phones to drop (or be unable to make) calls and transmitting data to the government that they would not otherwise have transmitted to the government. This considerable intrusion into the private affairs of innocent people should require a warrant because a judge, not the police, should determine that such interference is justified, and the warrant should mandate minimization of disruption and protection of bystanders’ data.
We participated in oral argument, which took place before the D.C. Court of Appeals in April 2017 and which the Washington Post discussed in an article here.
Later that month, the court issued an order, prompted by a question at oral argument, asking the parties to file supplemental briefs on the question, “What reasonable and legitimate expectation of privacy does a person have in his or her location information when the person possesses (outside his or her residence) a stolen cell phone capable of being located by a cell-site simulator or through real-time cell-site location information available to the cell phone owner or his or her telecommunications provider?”
In May 2017, we filed a motion for leave to file a supplemental brief addressing that question and were allowed to file a brief that argued that a person’s possession of a stolen cell phone doesn’t reduce her legitimate expectation of privacy any more than her possession of any other contraband would; the Fourth Amendment would have little force if people who were found with evidence of crime were automatically deemed to have had no protection against the search that discovered the evidence.
In September 2017, the court reversed Mr. Jones’s convictions, agreeing with us that the use of the StingRay required a search warrant.