The Department of Homeland Security says it developed a portable gunshot detection system

DHS has not disclosed details about the accuracy of the system. SDS, which is owned by, says its indoor gunshot detection system has a near-100 percent detection rate with fewer than one false alert per 5 million hours of use [although] critics claim that gunshot detection systems aren't effective enough and may cause more problems than they attempt to solve. “Past efforts to detect gunshots in real-time have not only wasted taxpayer dollars, they’ve put civilians in harm's way when officers are falsely told that fireworks and car backfires are active shooters," Surveillance Technology Oversight Project Executive director Albert Fox Cahn told Gizmodo. Fox Cahn added that there are privacy concerns around such systems, which "can often be misused as illegal wiretaps."

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