“Don’t do me like that, Ar,” the last words of an Oakland, California man shot in the street in June 2007 were later used to convict Arlito Johnson of second-degree murder. But the dying man’s last words weren’t overheard by a witness or police officer on the scene. They were captured by a network of microphones employed by the Oakland Police Department to detect gunfire called ShotSpotter.
Originally designed for the military to counter sniper fire in the field, ShotSpotter is a system of powerful sensors placed around a city to detect the location of a shooting by triangulation. Each ShotSpotter sensor includes microphones, high-tech hardware, and a connection to the Global Positioning System, which uses satellites to pinpoint the exact location. ShotSpotter is designed so that its sensors, perched on neighborhood rooftops and utility poles, alert law enforcement of a shooting even before people call 911 to report it.
“This new gunshot detection system is going to do a world of good in terms of going after the bad guys in this town,” Mayor Bill de Blasio said when he introduced the system in New York City. Created by SST, Inc., the technology is being used by around 90 police departments across the U.S, including those in Washington, Boston, and Miami.
DC police, one of its largest users, employ at least 300 ShotSpotter sensors across a third of the city. Between 2005 to 2013, sensors captured nearly 39,000 gunshot incidents, according to the Washington Post. “It is a valuable tool that provides almost instantaneous alerts that allow officers to be dispatched quicker for the sound of gunshots,” Police Chief Cathy L. Lanier told the Post. “It has also been instrumental in determining crime trends and establishing information in investigations.” (emphasis added) Therein lies the major problem with ShotSpotter. This technology captures more than just the sound of gunshots. Conversations and other audio picked up by the sensors are obtained without consent, and the subjects are unknowingly being recorded.
“There is clear evidence that ShotSpotter can record conversations,” the Electronic Frontier Foundation’s Nadia Kayyali told Business Insider. This has major Fourth Amendment implications. Because it constitutes a warrantless search and seizure by collecting public sounds, should potentially incriminating evidence picked up by the sensors be allowed as evidence in a criminal case? The murder case in Oakland is not an isolated instance. According to Fusion.net, the sensors recorded portions of a heated conversation before a killing in New Bedford, Massachusetts in 2011. Someone could be heard on the recording calling out “No, Jason! No, Jason!” before the shots were fired. Two men, Jason Denison and Jonathan Flores, were convicted of the murder. The recording was used as part of the prosecution’s case.