US Justice Department Urged to Investigate Gunshot Detector Purchases

The United States Justice Department (DOJ) is being asked to investigate whether a gunshot-detection system widely in use across the US is being selectively deployed to justify the over-policing of mainly Black neighborhoods, as critics of the technology claim.

Attorneys for the nonprofit Electronic Privacy Information Center—a leading US-based civil liberties group—argue that “substantial evidence” suggests American cities are disproportionately deploying an acoustic tool known as ShotSpotter in majority-minority neighborhoods. Citing past studies, EPIC alleges that data derived from these sensors has encouraged some police departments to spend more and more time patrolling areas where the fewest number of white residents live—an allegation disputed by SoundThinking, the system’s manufacturer.

In a letter today to Merrick Garland, the US attorney general, attorneys for EPIC call for an investigation into whether cities using ShotSpotter are running afoul of the Civil Rights Act—namely, Title VI, which forbids racial discrimination by anyone who receives federal funds.

“State and local police departments around the country have used federal financial assistance to facilitate the purchase of a slew of surveillance and automated decision-making technologies, including ShotSpotter,” EPIC says. Despite mounting evidence of ShotSpotter’s discriminatory impact, there is no indication that its Title VI compliance has ever been seriously assessed.

A spokesperson for SoundThinking says a statement by the company is forthcoming.

ShotSpotter has been deployed in more than 150 cities in the US, according to the company. It relies on internet-connected acoustic sensors, often attached to utility poles, and aims to detect gunfire using machine algorithms. SoundThinking says “acoustic experts” are on staff around the clock to review alerts and “ensure and confirm that the events are indeed gunfire.” The company claims its sensors have a 97 percent accuracy rate, disputing reports that alerts triggered by fireworks and other high-impact sounds affect the system’s accuracy.

EPIC is urging the DOJ to consider research that suggests ShotSpotter has produced “tens of thousands of false alerts” while simultaneously being deployed “in predominantly Black neighborhoods.” One such study, launched by the city of Chicago’s inspector general in 2021, noted that the “frequency of ShotSpotter alerts in a given area may be substantively changing policing behavior.” The agency concluded that, despite the city’s investment of $23-33 million, ShotSpotter alerts “rarely produce evidence of a gun-related crime, rarely give rise to investigatory stops, and even less frequently lead to the recovery of gun crime-related evidence during an investigatory stop.”

News investigations in Ohio and Texas have similarly raised doubts about the system’s effectiveness, revealing that in some cases its alerts have delayed responses to 911 calls. Working to expand the use of ShotSpotter in Houston in late 2020, the city also green-lit a pilot program that saw sensors deployed across two areas where communities are between 80 and 95 percent people of color.

EPIC is pressing Garland to investigate whether local law enforcement agencies have used federal grant money to buy ShotSpotter, and if so, ascertain whether those grants conformed with Title VI. Moreover, EPIC is seeking new guidelines for funding systems designed to automate police work: rules to ensure such arrangements are “transparent, accountable, and nondiscriminatory.” The attorney general should take additional steps, EPIC says, to ensure agencies dispersing federal funds are careful to assess whether tech companies meet “minimum standards of nondiscrimination” and that new police technologies are not only justified but necessary to achieve a “defined goal.”

The attorney general’s office did not immediately respond to a request for comment.

Ron Wyden, a leading privacy hawk in the US Senate, tells WIRED that he planned to urge Garland to adopt EPIC’s recommendations.

“There is more than enough evidence at this point to conclude that technologies like ShotSpotter do essentially nothing to stop crime,” Wyden says, “but instead have a well-documented discriminatory impact on marginalized and vulnerable communities.”

A spokesperson for SoundThinking told WIRED earlier this week that ShotSpotter has previously implemented safeguards meant to improve “impartiality” with regard to patrols, as well as other features designed to curb over-policing. The algorithms that drive patrol recommendations use “objective, noncrime data that mitigates potential bias,” the company said, adding that no personally identifiable information is used to determine where patrols are sent.

WIRED reported yesterday that SoundThinking has been quietly acquiring parts of Geolitica—formerly known as PredPol—the maker of an eponymous “predictive policing” tool. Researchers and critics have accused PredPol of perpetuating racial biases in policing by recycling historic crime data that was built on discriminatory police practices.

The danger, critics say, is that data- and AI-driven policing may prove an effective tool for “laundering” racist police conduct, granting it a veneer of scientific authority.

In 2021, Gizmodo and The Markup coauthored an investigation into PredPol and found that in many cases PredPol’s predictions predominantly targeted Black and Latinx residents. In a majority of the jurisdictions where the tool was being used, PredPol had urged police to mainly patrol neighborhoods in which the cities’ poorest people reside. ( The authors of this story were also members of the team that previously investigated PredPol, and EPIC cites the investigation and another Gizmodo report by an author of this story in its letter.)

“The possibility that ShotSpotter data would be an input for predictive policing tools raises yet another huge red flag,” says Chris Baumohl, an EPIC law fellow. “ShotSpotter has well-documented accuracy issues, and its sensors are placed based on historical crime data, baking in discriminatory policing patterns. Laundering this ‘dirty data’ through predictive policing tools only compounds this discriminatory impact.”

Following the Gizmodo-Markup investigation into PredPol, the Justice Department conceded in 2022 that it was unaware of how often the government was helping local police acquire “predictive policing” technology. For this purpose, it said, the DOJ has no “specific records” of how federal funding is used.