This case involves the surreptitious use of a cell site simulator, a cell phone surveillance device commonly known as a “Stingray.” These privacy-invasive devices have been employed by law enforcement agencies for years with little to no oversight from legislative bodies or the courts due to a deliberate policy of secrecy. Cell site simulators can be installed in vehicles, mounted on aircraft, or even carried by hand. They masquerade as the cellular tower antennas of wireless companies such as AT&T and Sprint, and in doing so, force all mobile phones within the range of the device that subscribe to the impersonated wireless carrier to emit identifying signals, which can be used to locate not only a particular suspect, but bystanders as well. In this case, Metropolitan Police Department (“MPD”) officers transmitted signals through the walls of homes and vehicles in a Washington, D.C., neighborhood to force Defendant’s mobile phone to transmit its unique serial number and, as a result, reveal its location. In the process, MPD also collected data about an unknown number of bystanders’ phones. Amici submit this brief to provide publicly available facts about cell site simulators’ capabilities to inform the Court of Fourth Amendment concerns unique to this technology. Amici also explain why, in light of the extreme secrecy surrounding law enforcement use of cell site simulators in the District, it is crucial that the Court provide guidance to police, prosecutors, and the public about the Fourth Amendment’s application to cell site simulator surveillance, even if the Court could resolve the case without reaching the merits of this issue.

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