Mayor Lori Lightfoot wants to employ a new tactic in the fight against crime and violence: sue gang members in civil court. But the plan is proving controversial.

According to a new report from the city’s inspector general, alerts by the gunshot detection system ShotSpotter used by the Chicago Police Department “rarely” lead to evidence of a gun crime. 

A new study by Northwestern University’s MacArthur Justice Center found that 86% of ShotSpotter alerts resulted in no report of any crime, leading to questions of the gunfire detection system’s value in violence reduction.