Summary: Evidence that background checks may reduce violent crime and total homicides is limited, and studies provide moderate evidence that dealer background checks reduce firearm homicides. Evidence of the effect of private-seller background checks on firearm homicides is inconclusive.

We identified eight studies since 2003 that examined the relationship between background checks and violent crime and met our inclusion criteria.[1] In reviews of the literature before 2003, Hahn et al. (2005) and the National Research Council (2004) reviewed Ludwig and Cook (2000), which found no difference in homicide rates across states that had laws comparable to those the Brady Act would impose (which initially included both background checks and a waiting period) and states that experienced larger changes in the law when the Brady Act was implemented.[2] The Ludwig and Cook study had an unfavorable ratio of estimated parameters to observations (less than one to six), meaning its parameter estimates and confidence intervals (CIs) may not be accurate because of model overfitting.

Gius (2015a) examined the effect of the federal Brady Act, state-mandated dealer background checks (either a check that was in place before the Brady Act or checks for categories of state-prohibited possessors other than those mandated by the Brady Act), and state-mandated private-seller background checks on gun-related homicides (the paper did not evaluate the effect of these variables on total homicides). The analysis of the federal Brady Act does not meet our criteria for inclusion because although the regression model evaluated whether changes occurred after implementation of the Brady Act, there was no comparison (control) group. State dealer background checks were found to significantly reduce firearm homicides by 20 percent (see the figure below), but the study’s design cannot distinguish whether this effect is attributable to a state’s implementation of background checks prior to the Brady Act, prohibition of more classes of people from owning guns after the Brady Act was passed, or some combination of the two. Private-seller background checks appeared to increase firearm homicides to levels 131 percent of what would be expected without the policy. Gius (2015a) does not provide information on the variation in state laws over the period evaluated, so the quality of causal effect estimates is uncertain.

La Valle (2013) examined the effect of the existence of a pre–Brady Act state background check law on gun homicides and total homicides (as well as other state policies). Using data from 56 large U.S. cities over 1980–2010, the author found in his preferred models (weighted models with a one-year lag and using control variables that were interpolated over the period, but where the dependent variable was not interpolated) that pre–Brady Act state background check requirements had an uncertain effect on either gun homicides or total homicides.