How firearm legislation impacts firearm mortality internationally: A scoping review.

Background: The literature on gun violence is broad and variable, describing multiple legislation types and outcomes in observational studies. Our objective was to document the extent and nature of evidence on the impact of firearm legislation on mortality from firearm violence. Methods: A scoping review was conducted under PRISMA-ScR guidance. A comprehensive peer-reviewed search strategy was executed in several electronic databases from inception to March 2024. Grey literature was searched for unpublished sources. Data were extracted on study design, country, population, type of legislation, and overall study conclusions on legislation impact on mortality from suicide, homicide, femicide, and domestic violence. Critical appraisal for a sample of articles with the same study design (ecological studies) was conducted for quality assessment. Findings: 5057 titles and abstracts and 651 full-text articles were reviewed. Following full-text review and grey literature search, 202 articles satisfied our eligibility criteria. Federal legislation was identified from all included countries, while state-specific laws were only reported in studies from the U.S. Numerous legislative approaches were identified including preventative, prohibitive, and more tailored strategies focused on identifying high risk individuals. Law types had various effects on rates of firearm homicide, suicide, and femicide. Lack of robust design, uneven implementation, and poor evaluation of legislation may contribute to these differences. Interpretation: We found that national, restrictive laws reduce population-level firearm mortality. These findings can inform policy makers, public health researchers, and governments when designing and implementing legislation to reduce injury and death from firearms. Funding: Funding is provided by the Strategy for Patient-Oriented Research (SPOR) Evidence Alliance and in part by St. Michael's Hospital, University of Toronto. Scoping review registration: Open Science Framework (OSF): https://osf.io/sf38n.