The effect of gun buy-back law reform on homicides and suicides in Australia

In this paper we use the synthetic control method (SCM) to estimate the causal effects of a national legislative reform accompanied by mandatory gun buy-backs in Australia on both suicide and homicide rates. Using a rich international dataset, we are able to separate not only these two death types, but also to distinguish deaths by firearm and by other means, thereby enabling us to test substitution-of-means hypotheses. Specifically, we apply the SCM to determine whether any reductions in firearm-related death rates where wholly or partly offset by increases in the use of other means (e.g., bladed weapons, poisons) to commit suicides and perpetrate homicides. Our findings show that these gun control policies substantially reduced both homicides and suicides by firearm, but also some evidence of other-means substitution.