Is ShotSpotter effective? Data on Detroit technology fuels debate

Detroit police are embracing the potential of gunshot detection technology to prevent violence, but some community groups and elected leaders question whether the investment is making a real impact on shootings.

Detroit’s City Council is set to vote later this month on a $7 million, federally-funded expansion of its gunshot detection contract with California-based ShotSpotter Inc. Discussions over the controversial contract in recent days have elicited protests, press conferences and lengthy comments from the public.

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Detroit Mayor Mike Duggan and Police Chief James White say ShotSpotter helps better identify where and when gun crimes occur, enabling police to dispatch officers faster and recover key evidence they wouldn’t have obtained by solely relying on 911 calls. But critics from the community and some council members argue DPD has failed to prove ShotSpotter is worth the investment and point to a growing body of research that portrays the technology as ineffective and potentially harmful for community relations.

City and police officials spent much of the summer making the case for ShotSpotter’s expansion while community organizations spread the word about their concerns. The debate intensified in the wake of several deadly mass shootings this summer. Detroiters on both sides of the issue have called for swift action to curb gun violence.

Branden Snyder, executive director of nonprofit community group Detroit Action, argues police are “overselling” the benefits of a costly program to score a political win. The city, he said, isn’t getting enough bang for its buck by doubling down on ShotSpotter. He would prefer to see that the one-time pandemic relief funds be used to prevent poverty and homelessness.

“Folks look at it as irresponsible to spend money on faulty surveillance as opposed to resources people actually need to survive,” Snyder said. “This money is supposed to be used to get communities out of the pandemic and take care of families.”

Detroit’s police chief agrees that strategic investment is needed for social programs that address root causes of crime, but stressed Monday “this isn’t an either-or proposition.”

“We have to make sure people feel safe, and I’m willing to say that I fully support this (ShotSpotter) technology and the city should commit resources for both law enforcement technology and social programming,” he said.

The city’s existing $1.5 million contract with ShotSpotter was approved in 2020 and is set to  expire at the end of 2023. The system is being used in 6 square miles of the 8th and 9th precincts, located on the city’s far west and east sides, respectively.

The new contract would expand ShotSpotter to 28 square miles with listening devices at a cost of $250,000 per square mile. The entire city would not be covered, just portions of eight police precincts. Under DPD’s plan, Precincts 2, 5 and 7 would not have sensors, meaning the downtown area, Cass Corridor and much of the city’s southeast side would be excluded.

Detroit plans to use $7 million in federal American Rescue Plan Act funding to pay for the expansion, which would expire in 2024. The council is also considering an extension of the original ShotSpotter contract for another year, also expiring in 2024.

The council’s Public Health and Safety Standing Committee voted Monday to advance both contracts to the full council for consideration on Sept. 20. However, the committee did so without a recommendation to approve them. Detroiters spent nearly two hours Monday voicing support and opposition to ShotSpotter.

At-Large Council Member Mary Waters said emotions are running high after the recent mass shootings, but “ShotSpotter has simply not proven to be effective.” Waters said ShotSpotter hasn’t worked for other cities and it has led to people being wrongly incarcerated.

“We must not be driven, by fear, to bad decisions,” Waters said Monday.

Can ShotSpotter help Detroit?

The crux of disagreement is whether ShotSpotter is truly effective. 

The company itself does not guarantee the technology will prevent crime. A contract approved in 2021 states ShotSpotter “does not warrant” that its software will “result in the prevention of crime, apprehension or conviction of any perpetrator of any crime” or “prevent any loss, death, injury, or damage to property due to the discharge of a firearm.”

White said 121 arrests resulted from 5,968 total gunfire incidents reported by ShotSpotter since it was implemented in March 2021, which means arrests were made in only 2% of the gunfire incidents that it detected. 

ShotSpotter reported 25,978 total gunshots in its Detroit coverage areas since March 2021. But ShotSpotter’s overall accuracy rate remains unclear. 

White said ShotSpotter is helping find shell casings and other evidence to create leads for officers and he said police identified 629 crime weapons thanks to ShotSpotter.

Detroit Police Chief James White held a Friday, Sept. 9, 2022 press conference focused on ShotSpotter, a gunshot detection company contracted with the city. (Screenshot | Facebook)

DPD reported 2,092 gunfire incidents were connected to ShotSpotter alerts this year, as of Sept. 5, which account for 10,265 shots fired. ShotSpotter has also led to the recovery of 73 guns in 2022, according to DPD data. Weapons were recovered in 3% of all gunfire incidents detected by ShotSpotter this year. 

Critics argue it’s a low rate of success for an expensive program. But White said ShotSpotter is making criminals think twice about causing trouble in areas where the system’s audio sensors are listening for gunshots. DPD has recorded 13 fatal shootings inside ShotSpotter areas this year, compared to 18 fatal shootings in the same areas at this point in 2021. White said those areas also experienced a 43% reduction in shots fired incidents.

“If I told you that to catch a murderer it would cost us $7 million, what would your response to that be?” White asked BridgeDetroit during a Monday interview. “If I told you that 100 fewer people would have the opportunity of murdering someone in Detroit for $7 million, you’d say how much can we get for $14 million, right? It’s hard to measure when you’re talking about life and death.”

Detroit’s 8th and 9th precincts are some of the most violent in the city, which is why police said they were chosen for the initial contract. DPD data shows 176 fatal shootings occurred this year in precincts that aren’t covered by ShotSpotter.

Overall, violent crime this year has declined citywide. DPD data released the first week of September shows 12% fewer violent crimes across Detroit compared to this point in 2021, while violent crime is down by 9% from 2020. Fatal shootings are not separately recorded in DPD crime statistics, but non-fatal shootings citywide are down 12%.

DPD data shows criminal homicides increased 19% in the 9th Precinct compared to this time in 2021, while non-fatal shootings decreased by 16%. Homicides dropped by 8% in the 8th Precinct and non-fatal shootings there dropped 5%.

Council President Pro Tem James Tate, a former police department spokesperson, said each time there’s a high-profile shooting he sees a spike in support for ShotSpotter. However, he hasn’t seen enough clear data on ShotSpotter’s impact to know whether it’s having a real impact.

“I still have some questions that are outstanding, and I need (DPD) to respond for me to make that conclusion,” Tate told BridgeDetroit last week. 

District 2 Council Member Angela Whitfield-Calloway said her mind is made up. Despite what the police chief has said, she doesn’t believe ShotSpotter is reducing crime.

“After the (mass) killings in District 2 on Aug. 28, I was thinking perhaps I would change my mind in terms of my support for ShotSpotter, but just looking at the different cities that use ShotSpotter I can’t support this,” Whitfield-Calloway said.

“I just don’t think this is what we need to address the crime issue in the City of Detroit,” she added. “There has to be another way. That way, in my opinion, is not ShotSpotter.”

How ShotSpotter works

ShotSpotter uses wireless microphone and sound sensors placed on top of buildings, lamp posts and towers to listen for gunfire. Algorithms are used to identify potential gunshots, which are reviewed by ShotSpotter technicians before Detroit police are sent an alert with time and location data. DPD has a dedicated ShotSpotter unit that responds to the alerts. 

ShotSpotter can only detect outdoor gunshots. The city’s contract states that in certain areas, obstacles and ambient noise may make it difficult to accurately identify the location of gunshots.

Detroit has “exclusive” ownership of all data created through its partnership with ShotSpotter, but the company can use data gathered in Detroit for internal research to improve its product. ShotSpotter is required to delete data 60 days after its contract with Detroit is terminated. 

The company is contractually obligated to meet a 90% accuracy standard. Detroit is responsible for informing ShotSpotter when gunfire is missed or reported in the wrong location in order to calculate the performance rate.

ShotSpotter’s contract with Detroit notes fireworks can mistakenly trigger an alert and that ShotSpotter doesn’t count the 48-hours around New Year’s Eve and July 4 in its accuracy reporting specifically because of holiday fireworks.

In early June, BridgeDetroit requested all reports of incorrect locations of ShotSpotter alerts, missed gunfire incidents and reports of false positive detections since the technology was implemented in March 2021. The city sought an extension that expired on June 29. Officials have not responded since. 

According to the ShotSpotter contract, DPD can request quarterly performance reports that show the number of calls for service, the level of urgency of the call and whether the problem was resolved. DPD said it has not asked for these reports due to data privacy concerns. 

Jackson Vidaurri, a DPD spokesman, said in an email that DPD has no plans to request call center performance reports from ShotSpotter because it would require the department to provide detailed dispatch data to ShotSpotter. Vidaurri said that data contains sensitive information that DPD protects by policy.

‘Rarely produces evidence’

Molly Kleinman, managing director of the Science Technology and Public Policy Program at the University of Michigan, oversaw a policy brief on ShotSpotter created on behalf of community organizations like We the People Action Fund. The Sept. 1 report from UM cites a growing body of research on ShotSpotter’s use in other cities that suggests the tool isn’t as effective as advertised. 

“I’m not aware of any reduction in crime from ShotSpotter,” Kleinman said in an interview. “That’s not something that I’ve seen evidence of.”

A 2021 report by Chicago’s independent Office of the Inspector General determined that evidence of a gun-related crime was only found in 9% of ShotSpotter alerts that police there responded to. The report concluded the data “does not support a conclusion that ShotSpotter is an effective tool in developing evidence of gun-related crime.”

Another study by the MacArthur Justice Center in 2021 found 89% of ShotSpotter alerts in Chicago turned up no gun-related crime and 86% led to no report of any crime at all. 

Chicago is the company’s largest customer. The city signed a $33 million contract in 2018 and opted to extend the contract in 2020. 

Proponents of ShotSpotter say the technology is needed to identify gunshots when Detroiters aren’t calling 911 to report it themselves. Vidaurri said only 711 of the 7,503 gunshots detected by ShotSpotter in the two precincts since March 2021 had a 911 call associated with it. 

White says residents have become “desensitized” to gunshots in their community and are less likely to call 911 to report shootings. 

“There are also people who are worried about their own safety,” he said. “One of the things that ShotSpotter allows us to do is to take that component out.”

Kleinman said research shows ShotSpotter has led to fewer 911 calls in cities that deployed it. 

A 2021 study looking at St. Louis County in Missouri by the Policing Project at NYU School of Law found police were alerted to four times as many gunshots, but 911 calls declined in areas where ShotSpotter was used. The report suggested ShotSpotter gave residents less incentive to report gunfire. The study also found no effect on arrest rates or other crimes in St. Louis.

BridgeDetroit reviewed 911 call data for shootings in progress and ShotSpotter alerts posted on the city’s website from June 28 to Sept. 5. It shows, on average, officers responded to ShotSpotter alerts more quickly than 911 calls.

The data shows officers were dispatched within 6.4 minutes to a ShotSpotter alert and arrived on scene in under 13 minutes. The average dispatch time for 911 calls reporting a shooting in progress was 23.6 minutes over that same time period. It took officers on average 33 minutes to arrive on the scene, data shows. 

Snyder, of Detroit Action, argues that police are unreliable in Detroit.

“There’s a historic distrust against our police system in general, and what things they respond to,” he said. “It’s fair to say people aren’t calling, but it stems back to the why. People don’t feel like (police) are going to be responsive to them.”

Detroiters demand solutions 

Duggan and White said ShotSpotter could have helped police thwart the gunman connected to the Aug. 28 mass shooting that left three Detroiters dead and injured another. Police did not receive a 911 call after the first shots fired at 4:45 a.m., but the shooting wasn’t in an area using ShotSpotter or where it would be expanded, based on DPD’s plans.

White also suggested that ShotSpotter could have saved the life of Detroit Police Officer Loren Counts, who was fatally shot July 6 while responding to a 911 call near Joy Road and Marlowe Street on Detroit’s west side. White said Monday that ShotSpotter would have let Counts know where the gunfire was coming from, which could have prevented him from being ambushed.

The recent shootings have convinced some Detroiters to support ShotSpotter. Danielle Hall, a neighborhood organizer and vice president of Oak Grove Community Group, said residents want action.

Danielle Hall, a neighborhood organizer and vice president of Oak Grove Community Group, said she supports expanding ShotSpotter to help police address gun violence in Detroit. She organized a vigil for victims of an August mass shooting on Wednesday, Sept. 8, 2022. (BridgeDetroit Photo by Malachi Barrett)

“I would rather know that (ShotSpotter) is there and we can tap into it than know it’s not there at all,” Hall said. 

Other residents have questioned how police expect the community to trust that the technology won’t be misused. White has rejected the idea that ShotSpotter is a surveillance tool, since its audio sensors aren’t triggered by voices. They are set off by loud noises of a certain decibel.  

“There still is a lot of misinformation about ShotSpotter,” White said. “It is not a surveillance tool. It’s not listening. It’s not monitoring you or I as a member of the community. What it’s monitoring is shots.”

But Kleinman fundamentally disagrees. “Placing microphones all over the city is a kind of surveillance,” she said. 

Sandra Turner-Handy, president of the 9th Precinct Community Relations Council, said ShotSpotter has brought more police attention to “the most violent zip code in the city.” 

“ShotSpotter allows us to target these areas and get these people that should not have guns off the street,” Turner-Handy said. “Our community leaders are OK with it.”

Council Member Gabriela Santiago-Romero has opposed the technology, arguing DPD hasn’t provided enough evidence to justify an expansion. On Friday, she held a press conference alongside activists with We the People Action Fund and Michigan Liberation.

Detroit City Council Member Gabriela Santiago-Romero speaks in opposition to ShotSpotter on Friday, Sept. 9, 2022 press conference at the Coleman A. Young Municipal Center in Detroit, Mich. (BridgeDetroit Photo by Malachi Barrett)

“Our residents need investment in truly affordable housing, accessible health care, reliable transportation, clean air and water, green spaces, childcare, local markets with fresh food and jobs with fair wages,” she said. “We need to support preventative solutions programs and initiatives, not reactionary ones.”

White convened his own press conference on ShotSpotter hours later, touting it as an “effective tool” and rebuffing media reports and opposition from some council members.

“Anytime that someone is victimized in a community with a non-fatal shooting or murder, getting that person off the street is essential,” White said.



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