Comprehensive background check policy and firearm background checks in three US states

Area of Science:

• Public Health
• Criminology
• Health Policy

Background:

• Comprehensive background check (CBC) policies are hypothesized to reduce firearm violence by extending background checks to private firearm sales.
• No prior studies have empirically determined if CBC policies increase firearm background checks, an expected intermediary outcome.

Purpose of the Study:

• To evaluate the association between CBC policies and firearm background check rates in Delaware, Colorado, and Washington.
• To assess the impact of CBC policies on an expected intermediary outcome for firearm violence reduction.

Main Methods:

• Utilized the synthetic control group method to estimate counterfactual trends in monthly firearm background check rates.
• Analyzed data from January 1999 to December 2016, covering handguns, long guns, and combined types.
• Conducted permutation tests and multiple sensitivity analyses to ensure result robustness.

Main Results:

• Firearm background check rates increased by 22%-34% in Delaware following CBC policy enactment.
• No significant overall changes in background check rates were observed in Washington and Colorado.
• Results remained robust across different comparison groups and statistical methodologies.

Conclusions:

• CBC policies were associated with increased firearm background checks solely in Delaware.
• External data suggest modest increases in private-party checks in Washington and non-gun show sales in Colorado.
• Potential non-compliance with CBC policies may explain the lack of observed overall increases in background checks in Washington and Colorado.