Gun Policy Research Review

The primary focus of our analysis was the systematic review of 18 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 ten of the 18 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.

View the research methodology

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.

Policies Regulating Who May Legally Own, Purchase, or Possess Firearms

  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
Extreme Risk Protection Orders

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 for how extreme risk protection orders affect suicide.

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 for how minimum age requirements affect mass shootings.

No studies met our criteria.

There is limited evidence that minimum age requirements decrease firearm suicides.

There is inconclusive evidence for how minimum age requirements affect unintentional firearm deaths.

There is inconclusive evidence for how minimum age requirements affect homicides.

Prohibitions Associated with Domestic Violence

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 for how prohibitions associated with domestic violence affect suicide.

No studies met our criteria.

There is moderate evidence that prohibitions associated with domestic violence decrease intimate partner 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 inconclusive evidence for how prohibitions associated with mental illness affect suicide.

No studies met our criteria.

There is limited evidence that prohibitions associated with mental illness decrease violent crime.

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 for how surrender of firearms by prohibited possessors has an effect on violent crime.

Policies Regulating Firearm Sales and Transfers

  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.

There is inconclusive evidence for how background checks affect firearm manufacturers or retailers.

No studies met our criteria.

There is inconclusive evidence for how background checks affect mass shootings.

No studies met our criteria

There is inconclusive evidence for how background checks affect suicide.

No studies met our criteria.

There is moderate evidence that background checks decrease firearm homicides.

Bans on Low-Quality Handguns

No studies met our criteria.

There is inconclusive evidence for how bans on low-quality handguns affect firearm purchases.

No studies met our criteria.

No studies met our criteria.

No studies met our criteria

There is inconclusive evidence for how bans on low-quality handguns affect suicide.

No studies met our criteria.

There is inconclusive evidence for how bans on low-quality handguns affect 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 in the short term.

No studies met our criteria.

There is inconclusive evidence for how bans on the sale of assault weapons and high-capacity magazines affect mass shootings.

No studies met our criteria.

No studies met our criteria.

No studies met our criteria.

There is inconclusive evidence for how bans on the sale of assault weapons and high-capacity magazines affect homicides.

Firearm Safety Training Requirements

No studies met our criteria.

There is inconclusive evidence for how firearm safety training requirements affect firearm purchases.

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 for how firearm safety training requirements affect homicides.

Firearm Sales Reporting, Recording, and Registration Requirements

No studies met our criteria.

There is inconclusive evidence for how firearm sales reporting, recording, and registration requirements affect firearm purchases .

No studies met our criteria.

There is inconclusive evidence for how firearm sales reporting, recording, and registration requirements affect mass shootings.

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.

There is inconclusive evidence for how licensing and permitting requirements affect firearm manufacturers or retailers.

No studies met our criteria.

There is inconclusive evidence for how licensing and permitting requirements affect mass shootings.

No studies met our criteria.

There is limited evidence that licensing and permitting requirements decrease suicide.

No studies met our criteria.

There is inconclusive evidence for how licensing and permitting requirements affect homicides.

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.

Waiting Periods

No studies met our criteria.

There is inconclusive evidence for how waiting periods affect firearm ownership, firearm manufacturers or retailers, or firearm purchases.

No studies met our criteria.

There is inconclusive evidence for how waiting periods affect mass shootings.

No studies met our criteria.

There is moderate evidence that waiting periods decrease firearm suicides.

No studies met our criteria.

There is moderate evidence that waiting periods decrease homicides.

Policies Regulating the Legal Use, Storage, or Carrying of Firearms

  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
Child-Access Prevention Laws

No studies met our criteria.

There is inconclusive evidence for how child-access prevention laws affect firearm manufacturers or retailers.

No studies met our criteria.

There is inconclusive evidence for how child-access prevention laws affect mass shootings.

No studies met our criteria.

There is supportive evidence that child-access prevention laws decrease firearm self-injuries among young people.

There is supportive evidence that child-access prevention laws decrease unintentional firearm injuries and deaths among young people.

There is limited evidence that child-access prevention laws decrease assaults.

Concealed-Carry Laws

No studies met our criteria.

There is inconclusive evidence for how concealed-carry laws affect firearm ownership and purchases.

No studies met our criteria.

There is inconclusive evidence for how concealed-carry laws affect mass shootings.

No studies met our criteria.

There is inconclusive evidence for how concealed-carry laws affect suicide.

There is inconclusive evidence for how concealed-carry laws affect unintentional injuries and deaths.

There is limited evidence that concealed-carry laws increase violent crime.

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.

Laws Allowing Armed Staff in K–12 Schools

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.

Stand-Your-Ground Laws

There is inconclusive evidence for how stand-your-ground laws affect defensive gun use.

There is inconclusive evidence for how stand-your-ground laws affect firearm ownership and purchases.

No studies met our criteria.

There is inconclusive evidence for how stand-your-ground laws affect mass shootings.

No studies met our criteria.

There is inconclusive evidence for how stand-your-ground laws affect suicide.

No studies met our criteria.

There is supportive evidence that stand-your-ground laws increase firearm 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 rigor 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 serious 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—at least one of which was not compromised by serious methodological weaknesses⁠—found significant effects in the same direction, and contradictory evidence was not found in other studies with equivalent or stronger methods.
Supportive
At least three studies not compromised by serious methodological weaknesses found suggestive or significant effects in the same direction using at least two independent data sets.

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.