The Repeal of Comprehensive Background Check Policies and Firearm Homicide

Introduction: In 2014, firearms killed 32,279 people in the United States.(Kochanek, Murphy, Xu, & Tejada-Vera, 2016) Homicide is the third leading cause of death among people age 15-34, and firearms are involved in over 75% of these homicides.(National Center for Injury Control and Prevention) Federal law requires licensed retailers, but not private parties, to conduct background checks on prospective purchasers with the goal of preventing prohibited persons from obtaining guns. Until November of 1998, Indiana and Tennessee required background checks for all handgun transfers, including among private parties. Our objective was to estimate the effect of the repeal of comprehensive background check policies in Indiana and Tennessee on firearm homicide rates.

Methods: We used a quasi-experimental comparative case study design to compare age-adjusted homicide rates in Indiana and Tennessee to weighted control groups using annual state-level data over the time period 1984-2014 (excluding 2001). Our main outcome was age-adjusted firearm homicide rates per 100,000 state residents. We used the synthetic control group method to estimate the counterfactual trajectories of firearm homicide for Indiana and Tennessee. Only states at risk of repeal of CBC policies were included in the donor pool for creating the synthetic control states. The following information was used to create our synthetic states: demographic information on age, race/ethnicity, urban/rural residents, and sex; socioeconomic indicators including percent with a high school degree, percent below the poverty line, median income, state Gini coefficient, and percent unemployed; and crime related information including incarceration rates, violent crime rates, and law enforcement employees. An estimate of the prevalence of gun ownership, and pre-intervention firearm homicide rates were also included in our models.

Results: Preliminary results suggest that the rates of firearm homicides in Indiana and Tennessee were slightly higher than in their synthetic counterparts after the repeal of CBC policies in 1998. However, the differences were within the range of what could be expected given natural variation. After 1998, the average age-adjusted firearm homicide rates in Indiana and Synthetic Indiana were 3.91 and 3.26 per 100,000 people respectively. The rates for Tennessee and Synthetic Tennessee were 5.24 and 4.96 per 100,000 people respectively.

Conclusion: Our results suggest the repeal of CBC policies had little to no impact on the rates of firearm homicide in Indiana and Tennessee. This has important implications for CBC laws. More evidence on the impact of CBC policies from other states is needed.