Thinking Through the ShotSpotter Debate

Robert VerBruggen Fellow

Recent years have seen significant activism against “gunshot detection technology,” or GDT— most prominently, the ShotSpotter product. This technology monitors neighborhoods for loud percussive sounds likely to be gunshots and—after a brief review process to limit false positives— alerts the police to the incidents and their locations. Opponents claim that the technology is inaccurate, racially biased (as sensors are disproportionately placed in minority neighborhoods), ineffective in helping police respond to crime, and simply not worth the cost. The purpose of this report is to dispassionately assess the evidence regarding each of these criticisms of GDT. Key findings include: • Racial bias: Sensors appear to be placed based on levels of gun violence—i.e., where they are most needed—though these areas do tend to be disproportionately minority. • Accuracy: There are relatively few proven false alerts. However, police often fail to find actionable evidence of a shooting when responding. • Effectiveness: ShotSpotter delivers on its promise of getting police to shooting scenes faster, identifying gunfire that otherwise would have gone unnoticed, and increasing evidence collection. But many studies are unable to measure increases in clearance rates or reductions in shootings in places where GDT is deployed. • Costs: The direct costs of GDT are generally a tiny fraction of total police spending in big cities, and officers spend a relatively small share of their total time responding to alerts, though resource- and staff-constrained departments will feel these burdens most acutely. The cost-benefit trade-off of GDT will vary from department to department, especially because some are better equipped than others to handle the additional police workload and comprehensively process new evidence. In addition, reasonable people may disagree about how to value the technology’s proven benefits to investigations in light of unclear effects on clearance and crime rates. One sensible approach is for departments to focus primarily on hiring adequate staff to respond to calls and to create a strong infrastructure to support investigations. Departments can then explore whether the additional information provided by GDT is worth the costs.

New York: Manhattan Institute 2025. 21p.