Gun Policy Research Review

The primary focus of our analysis was the systematic review of 13 broad classes of gun policies that have been implemented in some states and the effects of those policies on eight outcomes. We produced research syntheses that describe the quality and findings of the best available scientific evidence. Each synthesis presents and rates the available evidence and describes what conclusions, if any, can be drawn about the policy’s effects on outcomes. In many cases, we were unable to identify any research that met our inclusion criteria (which required a study to provide minimally persuasive evidence for a policy’s effects).

Overall, we found statistically significant evidence that seven of the 13 policies affect four of the main outcomes. For the remaining policies from our analysis, either the policies had inconclusive effects on outcomes or no research about the policies met our inclusion criteria. This does not mean that these policies are ineffective; they might well be quite effective. Instead, it partly reflects shortcomings in the contributions that scientific study can currently offer to policy debates in these areas.

Strength of Evidence for Relationships Between Gun Policies and Gun Use Outcomes

Here, we show the strength of evidence for relationships between all of the policies and outcomes we examined. Click on any cell with an evidence strength to view a more-detailed analysis.

	Gun Use Outcomes
Gun Policies	Defensive Gun Use	Gun Industry Outcomes	Hunting and Recreation	Mass Shootings	Officer-Involved Shootings	Suicide	Unintentional Injuries and Deaths	Violent Crime
Background Checks	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that background checks have an effect on mass shootings.	No studies met our criteria	There is moderate evidence that this background checks decrease suicide.	No studies met our criteria.	There is moderate evidence that background checks decrease firearm homicides.
Bans on the Sale of Assault Weapons and High-Capacity Magazines	No studies met our criteria.	There is limited evidence that bans on the sale of assault weapons and high-capacity magazines increase the price of banned firearms.	No studies met our criteria.	There is inconclusive evidence that bans on the sale of assault weapons and high-capacity magazines have an effect on mass shootings.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that bans on the sale of assault weapons and high-capacity magazines have an effect on violent crime.
Child-Access Prevention Laws	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that child-access prevention laws have an effect on mass shootings.	No studies met our criteria.	There is supportive evidence that child-access prevention laws decrease self-injuries.	There is supportive evidence that child-access prevention laws decrease unintentional injuries and deaths among children.	There is inconclusive evidence that child-access prevention laws have an effect on violent crime.
Concealed-Carry Laws	No studies met our criteria.	There is inconclusive evidence that concealed-carry laws have an effect on gun ownership.	No studies met our criteria.	There is inconclusive evidence that concealed-carry laws have an effect on mass shootings.	No studies met our criteria.	There is inconclusive evidence that concealed-carry laws have an effect on suicide.	There is limited evidence that concealed-carry laws increase unintentional injuries among adults.	There is limited evidence that concealed-carry laws increase violent crime.
Firearm Sales Reporting Requirements	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.
Gun-Free Zones	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.
Licensing and Permitting Requirements	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that licensing and permitting requirements have an effect on mass shootings.	No studies met our criteria.	There is inconclusive evidence that licensing and permitting requirements have an effect on suicide.	No studies met our criteria.	There is inconclusive evidence that licensing and permitting requirements have an effect on violent crime.
Lost or Stolen Firearm Reporting Requirements	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.
Minimum Age Requirements	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that minimum age requirements have an effect on mass shootings.	No studies met our criteria.	There is limited evidence that minimum age requirements decrease suicides among children.	There is inconclusive evidence that minimum age requirements have an effect on unintentional deaths.	There is inconclusive evidence that minimum age requirements have an effect on homicides.
Prohibitions Associated with Mental Illness	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is limited evidence that prohibitions associated with mental illness decrease suicide.	No studies met our criteria.	There is moderate evidence that prohibitions associated with mental illness decrease violent crime.
Stand-Your-Ground Laws	There is inconclusive evidence that stand-your-ground laws have an effect on defensive gun use.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that stand-your-ground laws have an effect on suicide.	No studies met our criteria.	There is moderate evidence that stand-your-ground laws increase homicides.
Surrender of Firearms by Prohibited Possessors	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that surrender of firearms by prohibited possessors has an effect on violent crime and partner homicides.
Waiting Periods	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that waiting periods have an effect on mass shootings.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence that waiting periods have an effect on violent crime and partner homicides.

Strength of Evidence Definitions

No studies: No studies meeting our inclusion criteria evaluated the policy’s effect on the outcome.
Inconclusive: Studies with comparable methodological strengths identified inconsistent evidence for the policy’s effect on an outcome, or a single study found only uncertain or suggestive effects.
Limited: At least one study meeting our inclusion criteria and not otherwise compromised by noted methodological weaknesses reported a significant effect of the policy on the outcome, and no studies with equivalent or stronger methods provided contradictory evidence.
Moderate: Two or more studies found significant effects in the same direction, and contradictory evidence was not found in other studies with equivalent or stronger methods.
Supportive: Three studies found significant effects in the same direction using at least two independent data sets, and contradictory evidence was not found in other studies with equivalent or stronger methods.

Note: In some cases, we found evidence for more than one sub-outcome for a given policy, and the strengths of the evidence differed across the sub-outcomes. For example, there is supportive evidence that child-access prevention laws decrease unintentional injuries and deaths among children, while there is limited evidence that these laws decrease the same outcome among adults. In this table, we show the highest strength of evidence for a policy and outcome relationship. To see details of all sub-outcomes, click on the associated box in the table.

Essays on Gun Policy Topics

The Relationship Between Firearm Availability and Suicide
Mar 2, 2018
Restricting Access to Firearms Among Individuals at Risk for or Convicted of Domestic Violence or Violent Crime
Mar 2, 2018
Mass Shootings: Definitions and Trends
Mar 2, 2018
The Effects of the 1996 National Firearms Agreement in Australia on Suicide, Violent Crime, and Mass Shootings
Mar 2, 2018
Education Campaigns and Clinical Interventions for Promoting Safe Storage
Mar 2, 2018
Mental Health Care Access and Suicide
Mar 2, 2018
The Relationship Between Firearm Prevalence and Violent Crime
Mar 2, 2018
The Challenges of Defining and Measuring Defensive Gun Use
Mar 2, 2018
Firearm and Ammunition Taxes
Mar 2, 2018
Methodological Challenges to Identifying the Effects of Gun Policies
Mar 2, 2018