By Dennis Mares

This document is part of the Response Guide series which is one of three series in the Problem-Oriented Guides for Police series. Response guides summarize knowledge about whether police should use certain responses to address various crime and disorder problems, and about what effects they might expect. This guide include examples and case studies as it covers the basic principles of gunfire detection and how it works; discusses the efficacy and police uses of acoustic gunshot detection systems, describing types of systems, experimental applications of the technology, and accuracy of acoustic gunshot detection systems; describes the analysis of acoustic gunshot detection system data; recommends best practices for responding to gunshots; and gives advice for implementing acoustic gunshot detection system, noting considerations such as coverage area, costs, personnel needs, interoperability with other systems, training requirements, and other factors that may impact decision-making.

PROBLEM-ORIENTED GUIDES FOR POLICE RESPONSE GUIDE SERIES NO. 14 Tempe, AZ: ASU Center for Problem-Oriented Policing, 2022. 29p

By Daniel S. Lawrence, Nancy G. La Vigne, Paige S. Thompson

This publication represents a technical summary report of the Urban Institute’s evaluation of the implementation, use, and impact of Gunshot Detection Technology (GDT) by law enforcement agencies in three cities: Denver, CO; Milwaukee, WI; and Richmond, CA. The goal of this study was to conduct a rigorous process and impact evaluation of GDT to inform policing researchers and practitioners about the impact GDT may have. To achieve this goal, we implemented a mixed-methods research design. Qualitative data collection included 46 interviews with criminal justice stakeholders to learn implementation processes and challenges associated with iDT, and 6 focus groups with 49 community members to learn how residents feel about policing efforts to reduce firearm violence and its use of GDT. Quantitative data collection included administrative data on calls for service (CFS), crime, and GDT alerts, as well as comprehensive case file reviews of 174 crimes involving a firearm. Quantitative analyses examined the impact of GDT by (1) comparing counts of gunshot notifications for GDT alerts to shooting-related CFS, (2) comparing response times of GDT alerts to shooting-related CFS, (3) examining the impact GDT has had on CFS and crimes, and (4) conducting a cost-benefit analysis of the GDT. Evaluation findings suggest that GDT is generally but not consistently associated with faster response times and more evidence collection, with impact on crime more uneven but generally cost-beneficial. We also conclude that agencies should implement GDT sensors strategically, train officers thoroughly, ensure that GDT data are used and integrated with other systems, and engage with community members early and often. More detailed information from this study will be available in forthcoming journal articles.

Washington, DC: Urban Institute 2019. 15p.

By: Eric L. Piza; George O. Mohler; Jeremy G. Carter; David N. Hatten; Nathan T. Connealy; Rachael Arietti; Jisoo Cho; Emily Castillo

This report presents a study on the impact of gunshot detection technology (GDT) on gun violence. The authors leverage over a decade of data from Kansas City, MO, and Chicago, IL, to measure how GDT contributes to policing and public safety. Both cities installed ShotSpotter GDT systems in 2012, allowing for a long-term quasi-experiment of program effects. Kansas City Police Department installed GDT in October 2012, with the target area covering approximately 3.5 square miles of the city and remaining unchanged to this day. Chicago Police Department installed GDT over approximately 3.0 square miles of the city in August 2012 with the coverage area expanding to 22 additional police districts between February 2017 and May 2018. This expansion led to approximately 100 square miles being covered by GDT in Chicago. The GDT system in Kansas City detected 11,517 gunfire incidents through the end of the study period (12/31/2019). The GDT system in Chicago detected 85,572 gunfire incidents over the full installation period from 2/6/17 – 12/31/19.1 Based upon ShotSpotter’s reported annual subscription costs of between $65,000 and $90,000 per square mile2, GDT coverage costs between $227,500 and $315,000 per year in Kansas City and between $8.8M and $12.3M per year in Chicago.

Final report submitted to the National Institute of Justice, 2023. 114p.

By Jillian Carr

Gunshot detection systems are used by policing agencies across the U.S. to detect incidents of firearms discharge. The most commonly used gunshot detection system is ShotSpotter, currently deployed in more than 100 cities across the U.S.1 Such systems typically use sensors, placed strategically throughout a particular area, to pinpoint the location of gunfire. Agencies that adopt the technology hope that it can help them reduce gun violence and make communities safer. They report that the technology can alert officers to gunshots that otherwise would not be reported, and that it can reduce officer response times by directing them to a more precise location. But the technology can be quite expensive—costing several hundred thousand dollars or more per year to maintain.

We found that in areas of St. Louis County that used ShotSpotter technology, police were alerted to four times as many gunshot incidents during the study period than in comparable areas without the technology. Despite responding to more calls related to gunfire, we found that reported assaults, which include gun-related assaults, fell by roughly 30 percent in areas with ShotSpotter. Moreover, the technology did not produce changes in the number or pattern of arrests. Because we did not find racially disparate effects on the prevalence of crime reporting or arrests from the adoption of the technology, ShotSpotter’s social costs appear minimal.

New York: Policing Project at New York University School of Law, 2021. 18p.