Impact of ShotSpotter Technology on Firearm Homicides and Arrests Among Large Metropolitan Counties: a Longitudinal Analysis, 1999-2016.

Over the past decade, large urban counties have implemented ShotSpotter, a gun fire detection technology, across the USA. It uses acoustic listening devices to identify discharged firearms' locations. We examined the effect of ShotSpotter with a pooled, cross-sectional time-series analysis within the 68 large metropolitan counties in the USA from 1999 to 2016. We identified ShotSpotter implementation years through publicly available media. We used a Poisson distribution to model the impact of ShotSpotter on firearm homicides, murder arrests, and weapons arrests. ShotSpotter did not display protective effects for all outcomes. Counties in states with permit-to-purchase firearm laws saw a 15% reduction in firearm homicide incidence rates; counties in states with right-to-carry laws saw a 21% increase in firearm homicide incidence rates. Results suggest that implementing ShotSpotter technology has no significant impact on firearm-related homicides or arrest outcomes. Policy solutions may represent a more cost-effective measure to reduce urban firearm violence.