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ShotSpotter gunshot detection system promises to alert authorities to gunfire in virtually real-time, while simultaneously pinpointing the spot where the shots were fired. The system of sensors, algorithms and artificial intelligence detects, locates and alerts police to gunfire and is located in many institutions around the US.

However, in a recent blistering report, the Chicago Inspector General’s office calls into question the effectiveness of the police department’s ShotSpotter technology.

“ShotSpotter alerts rarely produce documented evidence of a gun-related crime, investigatory stop, or recovery of a firearm,” the report states. “A large percentage of ShotSpotter alerts cannot be connected to any verifiable shooting incident.”

Indeed, the report’s authors say that out of 50,176 ShotSpotter alerts they examined from Jan. 1, 2020, to May 31, 2021, only 41,830 led to some kind of formal disposition. And out of those, only 4,556, indicated an actual gun offense.

The Chicago Police Department pushed back on the report’s conclusions. “ShotSpotter has detected hundreds of shootings that would have otherwise gone unreported,” the statement said. “Shotspotter is among a host of tools used by the Chicago Police Department to keep the public safe, and ultimately save lives,” as reported by

CPD noted in their statement that the technology’s deployment comes at a time of historically low 911 engagement. “Law enforcement can respond more quickly to locate and aid victims, identify witnesses, and collect forensic evidence,” the statement said.

But the OIG report suggested it has had a detrimental effect on policing in general.

“ShotSpotter technology in Chicago has changed the way some CPD members perceive and interact with individuals,” the report states. “Some officers, at least some of the time, are relying on ShotSpotter results in the aggregate to provide an additional rationale to initiate stops or to conduct a pat down once a stop has been initiated.”

CPD suggested the report was based on a mischaracterization of the way ShotSpotter is used. And that ultimately, communities victimized by gun violence benefit from its deployment.

A week beforehand, the Associated Press reported that its own investigation regarding communities where ShotSpotter has been deployed found serious flaws in the use of the technology as evidentiary support for prosecutors. The system can miss live gunfire right under its microphones and misclassify the sounds of backfiring cars or fireworks as gunshots, according to this investigation.