Chicago’s ShotSpotter Misses Gunfire, Manipulates Police Behavior: Report

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Photo by Nick M via Flickr

Late last week, a new report from the Chicago Office of Inspector General (OIG) concluded that the Chicago Police Department’s (CPD) use of the ShotSpotter technology not only rarely leads to evidence of a gun-related crime, but its prevalence and alerts are actually changing the way that some CPD members interact and police communities where alerts are frequent, according to The Trace, the Chicago Tribune, and the Office of Inspector General. 

ShotSpotter is a gunshot detection system that uses a network of acoustic sensors to identify and locate suspected gunshots. ShotSpotter data also heavily involves rigorous human analysis, as a monitoring team analyzes acoustic waveforms and sensor data to determine whether an alert is published to the police or dismissed as a false positive. 

This technology currently operates in more than 100 U.S. cities. To that end, Chicago’s system is one of the largest in the nation, spanning over 117 square miles in predominantly Black and Latinx communities, the OIG detailed. 

Not only is the Chicago ShotSpotter network physically expansive, but it’s also fiscally expensive. 

Chicago’s $33 million, three-year contract with ShotSpotter began on August 20, 2018 — but in December 2020, well before the end of the 2021 contract term, the City exercised an option to extend the contract, setting a new expiration date for August 19, 2023, the Chicago Tribune reports.

Now, advocates and leaders are increasingly questioning whether the extended contract is money well spent, noting that there’s mounting evidence that the system is ineffective at preventing shootings. 

What’s worse, some of the encounters that result from a ShotSpotter alert manifest injustice, with documented “patterns of discrimination and abuse,” The Trace details. 

‘Algorithms Ensnare the Innocent’

According to a recent Associated Press investigation covered by The Crime Report, prosecutors frequently use ShotSpotter for evidentiary support in gun violence cases. However, ShotSpotter’s algorithm-based and human-backed technologies can convey serious inaccuracies, like missing live gunfire right under the microphones, to misclassifying the sounds of fireworks or cars backfiring as gunshots. 

Beyond missing and misclassifying gunshots and loud noises, the data and “evidence” ShotSpotter technology creates can inadvertently land innocent people in jail, just as it seemingly did to Michael Williams, 65, who was accused of shooting and killing a young man in 2020 based on ShotSpotter information.

The key evidence against Williams was a clip of a noiseless security video showing a car driving through an intersection, and a loud bang picked up by a ShotSpotter.

Prosecutors argued that the noise detected was Williams shooting and killing the man. 

To that end, Williams was arrested approximately three months after the young man’s death, following the police investigation. ShotSpotter maintains that a forensic report request from the CPD was not made until February 1, 2021 — approximately six months after William’s arrest.

Ultimately, Williams had his case dismissed due to lack of evidence, weakening the confidence in ShotSpotter’s ability to be used by authorities, The Crime Report detailed. 

“I kept trying to figure out, how can they get away with using the technology like that against me?” said Williams, speaking publicly for the first time about his ordeal earlier in August. “That’s not fair.”

In response to the Associated Press’s investigation detailing that ShotSpotter is responsible for the tragedy of Mr. Williams arrest, a recent letter to customers from Ralph Clark, the company’s CEO, stated the following:

“The facts show that neither ShotSpotter’s initial alert nor its forensic report caused Mr. Williams’s arrest or incarceration, and we believe our forensic report may have contributed to his release in July 2021”.

Williams’ experience foreshadowed much of what Chicago’s OIG uncovered in their latest report in regard to CPD’s handling of ShotSpotter information.

ShotSpotter Rarely Leads to Helpful Evidence

The OIG report analyzed CPD and Office of Emergency Management and Communications (OEMC) data regarding all ShotSpotter alerts from January 1, 2020 to May 31, 2021, as well as analyzed investigatory stops confirmed to be linked to a ShotSpotter alert.

As the analysis stands, out of the total of 50,176 confirmed alerts, the OIG concluded that there’s no evidence that ShotSpotter is translating into safer streets, the report states. 

Some 41,830 of the total ShotSpotter alerts logged a police response, yet only 4,556 — 9.1 percent — resulted in viable evidence that a gun-related criminal offense had occurred.

While these numbers are enough to make anyone take a step back and reassess ShotSpotter’s validity, Deputy Inspector General for Public Safety Deborah Witzburg says that even if the technology was better at correctly identifying the sound of a gunshot, it does nothing to help the police to control gun crimes, therefore it does not have value for the city, according to a quote in the Chicago Tribune. 

“Our study of ShotSpotter data is not about technological accuracy, it’s about operational value,” said Witzburg, as quoted by The Trace. “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 combating violent crime.” 

Meanwhile, the very presence of the ShotSpotter technology is manipulating the way CPD members interact with members of Chicago’s communities, further instilling bias and increasing police presence in underserved neighborhoods, the OIG report explains. 

Specifically, the OIG reviewed instances in which CPD members rely, at least in part, on a perceived aggregate frequency of ShotSpotter alerts in an area to form the basis for an investigatory stop — or as part of the rationale for a pat-down once a stop has been initiated.

In other words, the Chicago Police Department has been using ShotSpotter “hotspot” data to rationalize over-policing. What’s more, this over-policing has a ballpark numerical figure, the OIG uncovered.

“OIG identified an additional 1,366 investigatory stops potentially associated with ShotSpotter alerts whose event number did not match any of the 50,176 confirmed and dispatched ShotSpotter alerts,” the report details.

ShotSpotter offered an official statement in response to the OIG’s report, as quoted by WGN9:

“It is important to point out that the Chicago Police Department continually describes ShotSpotter as an important part of their operations. The OIG report does not negatively reflect on ShotSpotter’s accuracy which has been independently audited at 97 percent based on feedback from more than 120 customers. Nor does the OIG propose that ShotSpotter alerts are not indicative of actual gunfire whether or not physical evidence is recovered. We would defer to the Chicago Police Department to respond to the value the department gets from being able to precisely respond to criminal incidents of gunfire. We work very closely with our agency customers to ensure they get maximum value out of our service.” 

Nevertheless, advocates argue that for the usefulness of ShotSpotter to be illuminated in Chicago, the city will have to demonstrate the worth of the sensors, and clearly detail how their role safeguards communities rather than hurts and overpolices them, the Chicago Tribune concludes.

The full Chicago Office of the Inspector General report can be accessed here. 

CEO Ralph Clark’s full statement can be further accessed here. 

Additional Reading: When Algorithms Ensnare the Innocent

Andrea Cipriano is a TCR staff writer.

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