Firearm laws are designed to limit the availability of firearms, often with the aim of reducing or preventing violent crimes.
These laws include the introduction of waiting periods or background checks for the purchase of firearms, outright weapons bans, and safe storage laws.
Laws may be applied at the local, regional or national level, and may target specific types of crime or be directed at all firearms offences.
This narrative summarises the findings of two systematic reviews. Review 1 is based on 29 studies and Review 2 is based on 38 studies. All of the primary studies in the reviews were based on evidence from the USA.
Overall, the evidence suggests that laws to restrict access to firearms have reduced crime, but there is some evidence that they have increased crime.
Review 1 aggregated the results of effect size estimates from primary studies. This analysis showed that firearms laws led to a small but statistically significant reduction in crime. Review 2 did not synthesise the results, instead reporting effect sizes from individual primary studies. These studies showed both statistically significant increases and decreases in crime, with the authors declaring no overall effect when considering all primary study evidence.
Review 1 found that enhanced prison terms for firearms offences, the introduction of waiting periods, and weapons bans all led to statistically significant reductions in crime. However, safe storage laws saw a small, statistically insignificant increase in crime.
Although the reviews were systematic, many forms of bias that could influence the study conclusions remain.
Review 1 did not seek out unpublished literature (and therefore did not account for publication bias).
The statistical tests conducted in this review were not reported with enough information to conclude that they were appropriate.
Review 1 also mentioned limitations in methodological quality within the primary studies it used to calculate the effect size, which may affect the reliability of the results.
Review 2 did not attempt a synthesis of effects across primary studies due to the limited number of studies and differences in outcomes.
Both reviews suggested mechanisms by which firearm laws can reduce violence. Bans are used to decrease the availability of firearms to potential offenders.
Background checks and waiting periods are also designed to decrease availability and restrict those individuals who have criminal histories or are at risk of self-harm from obtaining weapons. As such, these laws aim to reduce the opportunity for offenders to access weapons.
Laws that require guns to be unloaded and locked away also decrease availability, particularly to children who may use them in an unsafe manner. These practices are also believed to help reduce the theft of weapons.
Review 1 noted, however, that these laws might actually result in increased crime rates by reducing the deterrent effect that an armed public has on criminals. None of these suggested mechanisms are tested within either review.
The reviews noted a number of potential moderators, particularly when considering the type of law implemented, as outlined above in the section on effect size.
Review 2 also showed that different laws have different impacts on populations and offences; for example, it showed a statistically significant reduction in firearms suicide with greater regulation. Both reviews analysed the effects of these moderators with no theoretical foundation given for any expected differences.
Review 2 noted that there were difficulties implementing the instant background check system for firearms purchase, primarily due to a lack of records on some restriction categories, or because criminal records are difficult, or sometimes impossible, to retrieve.
It was also noted that the laws might be diluted by the fact that many US states have their own provisions requiring longer waiting periods for firearm purchases.
Neither of the reviews discussed the costs of implementing the intervention, and neither conducted a cost benefit analysis.
Overall, the evidence suggests that the intervention has reduced crime, but there is some evidence that it has increased crime. Firearm laws limit the availability of weapons, decreasing the opportunity to use them to commit crime. The implementation of these laws may vary by region, and more evidence is needed to understand in which conditions and for which crimes these laws work best.
Review 1: Makarios, M. D. and Pratt, T. C. (2012) 'The Effectiveness of Policies and Programs That Attempt to Reduce Firearm Violence: A Meta-Analysis', Crime and Delinquency, 58:2, 222-244
Review 2: Hahn, R. A., Bilukha, O., Crosby, A., Fullilove, M. T., Liberman, A., Moscicki, E., Snyder, S., Tuma, F. and Briss, P. A. (2005) 'Firearm Laws and the Reduction of Violence: A Systematic Review', American Journal of Preventative Medicine, 28, 40-71
This narrative was prepared by UCL Jill Dando Institute and was co-funded by the College of Policing and the Economic and Social Research Council (ESRC). ESRC Grant title: 'University Consortium for Evidence-Based Crime Reduction'. Grant Ref: ES/L007223/1.