US tech monitors for gunfire but critics say targets Black areas

  • U.S. homicides jump 44% in two years
  • Government may fund divisive gunshot detection systems
  • Critics say the tech is biased and doesn’t work

By Carey L. Biron

WASHINGTON, Aug 22 (Thomson Reuters Foundation) – When Toledo experienced a spike in gun violence, the Ohio city police force turned to a simple if controversial tool: it miked up part of the city to capture the sound of gunfire.

Advocates say that always-on microphone systems are a good way to catch criminals and help victims quickly, spawning a multimillion-dollar industry as U.S. shootings soar.

Sceptics, though, worry about rising surveillance, fearing it could widen the U.S. racial divide, invade peoples’ privacy and waste police time without cutting crime.

“There’s a lot of potential and good impact for this type of program, but the challenge is framing it in a way that shows we’re trying to help the community, and trying to implement it in areas where it has the most effect,” said Daniel Lawrence, a research scientist with CNA, a think tank.

It was back in 2019 that Toledo police first installed the ShotSpotter system, mounting an array of acoustic sensors on city buildings and other listening posts to alert law enforcement within a minute of gunfire being detected.

On the very first day, the alarm picked up its inaugural shot and police made an arrest.

In the following months, they made 70 more and realized that residents had only been reporting about one in five shooting incidents citywide, according to a case study.

Similar sensors have been installed in more than 130 cities, Chicago among them.

Workers review ShotSpotter alerts at a center in California in 2019. ShotSpotter / Handout via Thomson Reuters Foundation.

But the technology has also led to concerning incidents, critics say.

In April, a false alarm by ShotSpotter led police to stop and interrogate a 36-year-old man doing his family’s washing at a Chicago laundromat – an intervention that is now the subject of a class-action lawsuit filed by the MacArthur Justice Center at Northwestern University’s law school against the city.

The two cases reveal the complexity of gunshot sensors, seized on as a panacea for a nationwide rise in violent crime in the pandemic, with homicides surging by 44% from 2019 through 2021, according to the Council on Criminal Justice.

U.S. cities are rolling out ever more surveillance systems, and a federal Safer American Plan proposed by President Joe Biden would make more than $2.6 billion available for gunshot detection and other technologies.


Privacy advocates say the schemes are a waste of money – at best – and a new form of surveillance in already overpoliced communities at worst.

“We see cities blanketing certain neighborhoods, often majority-Black and Latino neighborhoods … with the promise that these systems can automatically detect and report gunshots,” said Albert Fox Cahn, executive director of the Surveillance Technology Oversight Project (STOP).

“But growing evidence says this technology does nothing of the sort: it’s falsely reporting a number of everyday sounds as being gunshots, and sending police on wild goose chases – a waste of policing time that can actually be deadly,” he said.

A report from the group last month found that 70% of New York police precincts that deployed ShotSpotter in 2018 were majority Black or Latino, while Cleveland, Atlanta and Kansas City, Missouri, focused almost entirely on such areas.

ShotSpotter says its system has a 97% aggregate accuracy rate, and rebuts suggestions of bias.

“ShotSpotter’s coverage areas are determined by police using objective historical data on shootings and homicides to identify areas most impacted by gun violence,” the company said in a statement to the Thomson Reuters Foundation.

A worker reviews ShotSpotter alerts at a center in California in 2017. ShotSpotter / Handout via Thomson Reuters Foundation.


The global gunshot-detection market, worth $594 million in 2020, is expected to grow to $979 billion by mid-decade, according to consultancy Markets and Markets.

The technology was initially developed for military use during the war in Iraq, said Lawrence.

Some systems use acoustic sensors with cameras that can swivel toward a perceived event.

ShotSpotter’s sensor arrays can triangulate the location of a potential gunshot, the company says, after which the audio is analyzed by computer before it is relayed to technicians and potentially onto law enforcement.

2020 report that Lawrence co-authored found the accuracy of gunshot detection was “relatively high” in the three cities surveyed – Denver, Milwaukee and Richmond, California.

The alerts doubled the number of police calls – but with mixed effects.

“In Richmond, we saw a reduction in violent crimes, led by a reduction in robberies,” Lawrence said, but only Denver saw an increase in arrests for crimes involving firearms.

In Chicago – among the worst U.S. cities for gun violence – the technology has detected hundreds of shootings that would otherwise go unreported, said police spokesperson Thomas Ahern.

“The system gives police the opportunity to reassure communities that law enforcement is there to serve and protect them,” he said by email.

Yet the report last month from STOP on ShotSpotter said its efficacy was “unproven”, and that it increases the risk of police violence without producing “any significant effect on firearm offenses”.

The company rejected the allegations, saying over 80% of shootings are not reported to police.

“ShotSpotter enables a fast, precise police response to nearly all outdoor gunfire in the coverage area to help save the lives of gunshot wound victims and capture critical evidence at the scene,” ShotSpotter said in a statement.


This month, activists launched a national campaign urging local officials to halt the use of gunshot-detection systems, saying the increased police focus on certain neighborhoods was itself problematic.

ShotSpotter alerts “are exposing folks to more harmful, more violent interactions with police,” said Alyxandra Goodwin, a Chicago-based activist with the Action Center on Race & the Economy advocacy group.

“There’s evidence of increased stop-and-frisk because ShotSpotter is in these neighborhoods.”

Last year, Goodwin and others unsuccessfully sought to push the city not to extend its ShotSpotter contract.

She says the money would do more to cut gun crime if it were spent on housing, jobs, education and mental health care.

Yet others insist that careful use of the technology can help rebuild fragile relations between communities and police.

Portland, Oregon, is considering ShotSpotter to combat an “unprecedented increase in gun violence” that saw 2019’s total of 199 shootings jump to 582 last year.

The 2022 tally had hit 673 by June alone.

A mayor-appointed citizen oversight group, which recently helped create a new community policing unit in hopes of fostering greater trust, last month recommended the sensor system, with caveats attached.

Members first researched community concerns, giving the go-ahead for that unit only if the system was properly tested, if sensors were fairly located and after wider community opinion was sought.

The technology can help build trust by showing local communities that police will respond – potentially breaking a vicious circle of residents arming themselves in pursuit of protection, said Pastor Ed Williams, who chairs the group.

Effective post-shooting investigations are also key to creating greater trust, said co-chair Kimberely Dixon.

“This isn’t just about you getting there, but also about the police investigation that winds up being more important,” she said. “This will lead to better investigations and better outcomes down the road.”

(Reporting by Carey L. Biron; Editing by Lyndsay Griffiths. Please credit the Thomson Reuters Foundation)