Skip to contents

ShotSpotter Alerts Rarely Result In Evidence Of Gun Crime, City Watchdog Says

ShotSpotter is touted by police for its real-time gunshot detection technology, but it has been under scrutiny for months. Previous reports determined it’s too unreliable for routine use.

A Chicago Police squad car on June 30, 2021.
Colin Boyle/Block Club Chicago
  • Credibility:

CHICAGO — The Police Department’s response to ShotSpotter alerts rarely produce evidence of a gun-related crime, and the technology changes the way responding officers interact with people in areas with the technology, the city’s top watchdog said in a report released Tuesday.

The Office of Inspector General found data it examined did “not support a conclusion that ShotSpotter is an effective tool in developing evidence of a gun-related crime,” according to a statement issued with the report.  

ShotSpotter is touted by police for its real-time gunshot detection technology, but it has been under scrutiny for months. Previous news media reports and analyses have determined it’s too unreliable for routine use.

Mayor Lori Lightfoot and the Police Department have defended the technology.

Activists have called on the city to cancel the contract, but records show the Police Department extended the agreement months ago, finalizing an extension in December to continue using ShotSpotter until late 2023. The deal is worth up to $33 million.

“If the department is to continue to invest in technology which sends CPD members into potentially dangerous situations with little information — and about which there are important community concerns— it should be able to demonstrate the benefit of its use in combatting violent crime,” Deborah Witzburg, deputy inspector general for Public Safety, said in the statement.

“The data we analyzed plainly doesn’t do that. Meanwhile, the very presence of this technology is changing the way CPD members interact with members of Chicago’s communities.”

Police spokesman Tom Ahern has defended the technology, saying it allows officers to respond “quickly to locate and aid victims, identify witnesses and collect foreseeing evidence,” instead of relying on 911 calls.

“ShotSpotter is among a host of tools used by the Chicago Police Department to keep the public safe and ultimately save lives,” Ahern said last month. “Using ShotSpotter, CPD receives real-time alerts of detected gunfire enabling patrol officers to arrive at a precise location of a shooting event quickly.”

After the report was published, Shotspotter said in a statement it would defer to the CPD regarding the value the technology has for the department. “We work very closely with our agency customers to ensure they get maximum value out of our service,” the company said.

The city watchdog analyzed data from the Police Department and the Office of Emergency Management for all ShotSpotter alert notifications Jan. 1, 2020-May 31, 2021, as well as investigatory stops confirmed to be associated with the department’s response to a ShotSpotter alert. 

The MacArthur Justice Center published its own study earlier this year. Over a nearly two-year period, ShotSpotter sent Chicago officers on more than 40,000 “dead-end deployments,” meaning officers never filed any kind of police report after responding to an alert, the center’s report said.

In that report, attorneys argued the technology’s lack of accuracy — along with its dominant use in predominantly Black and Brown communities — feeds “racialized patterns of overpolicing.”

The inspector general’s office found that police rely, “at least in part” on the perceived frequency of ShotSpotter alerts in an area to make investigatory stops or “as part of the rationale” for a pat-down once a stop has been made. 

More than 100 cities have contracts with ShotSpotter. In Chicago, the system covers 117 square miles across 12 police districts concentrated on the city’s South and West sides, making the city one of the company’s top customers.

Chicago police have used ShotSpotter since 2012, according to the inspector general. The department relies on the technology to pick up loud noises and determine if a boom or bang was a gunshot. ShotSpotter is said to pinpoint where the noise came from, within close proximity.

Vice magazine published a report in July about ShotSpotter alerts being manipulated at the request of police departments, fueling demands by activists that the city stop working with the company.

In an investigation published last week, the AP reported a ShotSpotter employee prepared forensic reports that were used in court to allege a defendant shot at police. The system also missed gunfire under its microphones and misclassified fireworks or cars backfiring as a gunshot, according to the report.

Alyx Goodwin, of the Action Center on Race and the Economy said local organizers still are committed to end the city’s use of the technology.

“This is a public health issue,” Goodwin said. “We want City Council to be more aware of the technology that CPD is using and also heed the words of their constituents. If constituents say they don’t want ShotSpotter but they do want housing or healthcare, City Council members should be listening.”

ShotSpotter did not immediately respond to a request for comment.


Activists Want City To Cut Ties With ShotSpotter — But Chicago Police Already Extended Its Contract Two More Years

Chicago Should Cancel ShotSpotter Contract After Report Shows Police Influence On Technology, Activists Say

85 Percent Of ShotSpotter Alerts Are Dead Ends — But Officers Coached To Think They’re Responding To Dangerous Situations, Study Finds

Subscribe to Block Club Chicago, an independent, 501(c)(3), journalist-run newsroom. Every dime we make funds reporting from Chicago’s neighborhoods.

Already subscribe? Click here to support Block Club with a tax-deductible donation. 

Listen to “It’s All Good: A Block Club Chicago Podcast” here: