With ShotSpotter staying in Chicago for the time being, dispute continues over the system’s usefulness

Early one morning last May, on a bungalow-lined street in Avalon Park, ShotSpotter detected real gunshots: more than half a dozen rounds fired.

It was a busy night, and officers didn’t make it to the scene for more than half an hour. But when they arrived they found 24-year-old Aréanah Preston, a Loyola law student and Chicago police officer, fatally shot on her front lawn.

Late one night in January, on a residential block of Auburn Gresham, ShotSpotter detected what likely were just fireworks.

But the alert sent officers out looking for a shooter, and when they got there they heard a loud bang. One officer opened fire in the direction of a boy who had just set off a firecracker, but did not hit him.

The episodes paint a picture of the limits of a controversial system Chicago has decided to keep around well past this summer’s Democratic National Convention after a protracted contract fight. Police see value in the system’s ability to bring them to trouble including at times when no one calls 911, but its usefulness may quickly downgrade from there, experts said.

In recent weeks, long-standing criticisms have intensified, among them that the system is inaccurate, expensive and disproportionately harms people of color. Some attorneys argue ShotSpotter shouldn’t be used in the courtroom or on the street, claims that judges could be sorting out for months if not years to come.

Mayor Brandon Johnson was an outspoken