Statement of Purpose Stolen firearms are commonly used in firearm assaults. The media have reported a recent increase in firearm thefts from vehicles, but there is little empirical evidence to determine underlying causes. We determined the association between the implementation of a 2014 Tennessee law allowing any citizen not prohibited from owning a firearm to carry a firearm in their vehicle on the rate of firearm thefts from vehicles.

Methods/Approach We use monthly data from the FBI’s National Incident-Based Reporting System (NIBRS) between 2009 and 2018 on firearm thefts from a vehicle for Tennessee and 13 control states without such a law. We use a quasi-experimental design with multiple-group interrupted time-series analysis to estimate the effect of the Tennessee law on firearm theft from a vehicle.

Results Comparison of thefts before and after the enactment of the 2014 Tennessee law show a significant increase in rates of firearm thefts from a vehicle: The average monthly rate was 1.99 per 100,000 before the implementation of the law and 3.26 per 100,000 after (Difference=1.27, t=15.105, p<0.001).

Conclusion While a law passed in Tennessee was intended to allow citizens to protect themselves against intruders in their vehicles, it was associated with a marked increase in firearm thefts from vehicles.

Significance and Contributions to Injury and Violence Prevention Science Allowing anyone to carry firearms in their vehicles can have serious unintended consequences due to the increased supply of unsecured firearms in vehicles. This has resulted in thousands of additional firearms flowing from firearm owners in Tennessee into illegal markets, which in turn can increase the supply of weapons for violent crimes. Additional policies, vehicle secure storage innovations, and behavioral interventions are urgently needed to stem this source of illegally obtained firearms.