Mayor Brandon deliberately uses a flawed UChicago Justice Project study to justify ending ShotSpotter
Mayor Brandon Johnson’s public embrace of a UChicago Justice Project report that claims police response times improved after ShotSpotter was disconnected is another instance in which political ideology appears to trump public safety. The mayor’s praise for the study — and his decision to eliminate ShotSpotter without a credible replacement — risks abandoning a technology that city officials and independent observers have tied to faster responses to shootings and in many cases, has saved lives.
CWB Chicago, which tracks shootings and constructs a “body count” of incidents where no 911 call was made or police were sent to the wrong location — Brandon’s Bodies — has flagged the Justice Project’s apparent selective use of the weeks and months to support its conclusions that one would hope was not deliberate. Equally troubling is the report’s failure to account for operational changes inside the Chicago Police Department that affect response capacity.
Regarding the selective use of data, according to CWB, UChicago Project director Robert Vargas acknowledged that before analyzing response times, his students removed all 911 calls involving shots fired from the city’s dataset. This means the faster response times did not include gunfire calls, “the only type of emergency ShotSpotter was designed to address” and the specific response times the mayor has cited to justify ending of ShotSpotter.
Incredibly, Vargas’ team compared response times from March 2024 through September 2024, when ShotSpotter was disconnected, to the six-month period following the technology being dismantled. According to CWB, “The before period included spring and summer months when 911 call volumes are heavy and neighborhood patrol officers were diverted to the Democratic National Convention, festivals, and other large events. The after period covered fall and winter when call volumes are lighter and officers were back on local patrol.”
Under Superintendent David Brown, the percentage of high‑priority calls with cars available to respond rose from roughly 19 percent in 2019 to nearly 60 percent before his departure; those availability metrics have declined each year since. The report’s timeframe and omissions make it read more like a post‑hoc justification for a political decision than a dispassionate analysis.
The Justice Project pairs the removal of ShotSpotter and the mayor’s “Community Violence Interrupters” (CVIs) initiative with improvements in measured response times and with a subsequent decline in shootings and murders. Nonetheless, it largely ignores other salient developments, including operational shifts under Superintendent Larry Snelling and prosecutorial changes in Cook County after Kim Foxx’s replacement.
In 2025, after the new State’s Attorney (Eileen O’Neill Burke) took steps to more aggressively oppose bond for repeat and violent offenders, Chicago experienced sharper declines in shootings and murders than in prior years. That timing — coupled with the return of the county jail population to near pre‑COVID levels — suggests multiple, concurrent drivers of crime trends beyond any single technology removal.
Reports such as UChicago Justice Project’s should be judged by their methodology, not by how well their conclusions align with a political preference. Too often the media treat such studies as authoritative without scrutinizing their sample windows, control variables, and potential selection bias. When WTTW and other outlets ran the Justice Project's findings practically as a press release, reporters missed the report’s methodological gaps; at a recent press conference, Mayor Johnson publicly thanked WTTW’s Heather Cherone for her story and praised the Justice Project study.
Medical literature underscores the point: Delays in prehospital care raise the risk of death for gunshot victims substantially. Studies on emergency response failures show that life-threatening emergencies typically require a response within 8 minutes to optimize survival. Overall mortality rate for gunshot wounds seen in trauma centers is approximately 27.4 to 33 percent. Increasing transport time to a trauma center by each minute is associated with a 2 percent increase in the odds of mortality.
It’s unfortunate the UChicago Justice Project study seems more driven by ideology than facts. How else to explain such misuse of data? UChicago isn’t the only prestigious city university to prioritize narrative over data. Loyola University, which has received almost $3 million in grants from Cook County to evaluate its pre-trial release program, has declared the program a success by looking at the percentage of those released who committed crimes which didn’t changed while ignoring the number of crimes that increased significantly.
On the specific question of ShotSpotter’s effect, the evidence that it reduces response times is straightforward: The system’s stated purpose is not to reduce crime rates directly but to detect gunfire events and speed lifesaving interventions. Police Superintendent Larry Snelling stated in early 2024 that officers applied life-saving techniques in over 150 incidents connected to ShotSpotter alerts, figures drawn from CPD's actual internal counting of officers applying life-saving techniques or earning Life-Saving Awards associated with alerts.
The University of Chicago Crime Lab did the math and concluded that lives saved due to ShotSpotter's capability is very likely much greater — primarily because it is enabling first responders to more quickly provide lifesaving treatment to gun violence victims. In response to Mayor Johnson's decision to gut the system, Civic Committee leaders' message to the mayor based on University of Chicago Crime Lab report was very clear: “Don’t cancel ShotSpotter unless the city could transition to something better.” Since unplugging the system in 2024, Johnson has even failed to seriously explore a better alternative as he had promised.
For the mayor’s far-left supporters who conflate racism with any statistics showing police stopping, arresting or incarcerating more Blacks and Latinos, the deployment of ShotSpotter in Chicago’s highest crime neighborhoods to ensure faster emergency response to shootings is somehow racist. Despite critics charging ShotSpotter is racist, support for keeping ShotSpotter is highest among Black (78 percent in favor) and Latino (73 percent) voters who live in communities where gun violence is highest. What do these residents know the mayor does not?
Mayor Johnson should explain why he abandoned a tool that city officials credited with saving lives and why he praises a report that appears to omit key operational and prosecutorial variables. If the city’s leadership believes ShotSpotter is ineffective, produce the full analysis and data to support it. If it’s about budget priorities note the city pays roughly $30 million a year to support a 150‑officer mayoral detail — three times what was spent annually on ShotSpotter.
Chicago leaders must be honest with residents. Policy decisions that affect life and death deserve more than convenience politics and sympathetic press coverage. If Mayor Johnson’s priority is public safety, he should ensure that policy rests on full data, careful methods, and an honest accounting of all concurrent reforms — not on a report that conveniently fits a preferred political ideology.
