Legal gun ownership and carrying are not associated with homicides in Brazil: a Bayesian analysis of state-level longitudinal data

The academic debate on the relationship between gun ownership and violence remains unresolved, with recent studies highlighting its complexity. In Brazil, most research has concluded that greater civilian access to firearms is associated with higher levels of violence, typically reflected in rising homicide rates. However, this literature relies heavily on proxy measures of gun ownership. While some of these proxies have been validated in the United States, their validity in the Brazilian context is uncertain. Moreover, prior studies have not examined how gun ownership relates to homicides, while accounting for state-level variation. This study addresses these gaps by analysing the association between legal gun ownership and number of homicides using official data on firearm possession and carrying rather than proxy measures. To capture regional heterogeneity, we employed Bayesian multilevel models with state-level variation explicitly modelled. The results suggest that legal gun ownership is unlikely to be a significant driver of the number of homicides. Instead, the substantial differences observed across states indicate that state-specific criminal justice policies and institutional contexts may play a more decisive role than the prevalence of legally owned and carried firearms.