Gun Policy Research Review

Using the best available scientific evidence, we systematically reviewed broad classes of gun policies to understand how they affect different outcomes in the United States.

We categorized the evidence for each study we reviewed as inconclusive, limited, moderate, or supportive. Some policies simply haven’t been studied enough, so an absence of evidence does not indicate that a policy is effective or ineffective.

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

The table below shows where there is evidence for how gun policies affect outcomes, as well as the strength of that evidence. The table does not show how much gun policies affect outcomes. Instead, the table shows how strong the evidence is that each gun policy has any effect on the outcomes.

Click on any table column heading, row heading, or filled cell below to learn more about the policy, outcome, or effect.

	Defensive Gun Use	Gun Industry Outcomes	Hunting and Recreation	Mass Shootings	Police 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.	There is inconclusive evidence for how extreme risk protection orders affect mass shootings.	No studies met our criteria.	There is limited evidence that extreme risk protection orders decrease total and firearm suicides.	There is inconclusive evidence for how extreme risk protection orders affect unintentional injuries and deaths.	There is inconclusive evidence for how extreme risk protection orders affect violent crime.
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 supportive evidence that higher minimum age requirements for purchasing a firearm decrease firearm suicides among young people.	There is inconclusive evidence for how minimum age requirements affect unintentional injuries and deaths.	There is inconclusive evidence for how minimum age requirements affect violent crime.
Prohibitions Associated with Domestic Violence	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 mass shootings.	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.	There is inconclusive evidence for how surrender of firearms by prohibited possessors affect mass shootings.	No studies met our criteria.	There is inconclusive evidence for how surrender of firearms by prohibited possessors affect suicide.	No studies met our criteria.	There is moderate evidence that surrender of firearms with expanded classes of prohibited possessors decreases firearm-involved intimate partner homicides.

Policies Regulating Firearm Sales and Transfers

	Defensive Gun Use	Gun Industry Outcomes	Hunting and Recreation	Mass Shootings	Police Shootings	Suicide	Unintentional Injuries and Deaths	Violent Crime
Background Checks	No studies met our criteria.	There is inconclusive evidence for how background checks affect gun industry outcomes.	No studies met our criteria.	There is inconclusive evidence for how background checks affect mass shootings.	There is inconclusive evidence for how background checks affect police shootings.	There is inconclusive evidence for how background checks affect suicide.	No studies met our criteria.	There is moderate evidence that background checks decrease total homicides and firearm homicides.
Bans of Low-Quality Handguns	No studies met our criteria.	There is inconclusive evidence for how bans of low-quality handguns affect gun industry outcomes.	No studies met our criteria.	No studies met our criteria.	No studies met our criteria.	There is inconclusive evidence for how bans of low-quality handguns affect suicide.	No studies met our criteria.	There is inconclusive evidence for how bans of low-quality handguns affect violent crime.
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 prices or sales of banned firearms in the short term.	No studies met our criteria.	There is limited evidence that bans on high-capacity magazines decrease mass shootings and fatalities.	There is inconclusive evidence for how bans on the sale of assault weapons and high-capacity magazines affect police shootings.	There is inconclusive evidence for how bans on the sale of assault weapons and high-capacity magazines affect suicide.	No studies met our criteria.	There is inconclusive evidence for how bans on the sale of assault weapons and high-capacity magazines affect violent crime.
Firearm Safety Training Requirements	No studies met our criteria.	There is inconclusive evidence for how firearm safety training requirements affect gun industry outcomes.	No studies met our criteria.	There is inconclusive evidence for how firearm safety training requirements affect mass shootings.	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 violent crime.
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 gun industry outcomes.	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.	There is inconclusive evidence for how firearm sales reporting, recording, and registration requirements affect suicide.	No studies met our criteria.	There is inconclusive evidence for how firearm sales reporting, recording, and registration requirements affect violent crime.
Licensing and Permitting Requirements	No studies met our criteria.	There is inconclusive evidence for how licensing and permitting requirements affect gun industry outcomes.	No studies met our criteria.	There is limited evidence that licensing and permitting requirements decrease mass shootings.	No studies met our criteria.	There is inconclusive evidence for how licensing and permitting requirements affect suicide.	No studies met our criteria.	There is inconclusive evidence for how licensing and permitting requirements affect 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.
Waiting Periods	No studies met our criteria.	There is inconclusive evidence for how waiting periods affect gun industry outcomes.	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 total homicides.

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

	Defensive Gun Use	Gun Industry Outcomes	Hunting and Recreation	Mass Shootings	Police 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 gun industry outcomes.	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 suicides among young people.	There is supportive evidence that child-access prevention laws decrease unintentional firearm injuries and deaths for children.	There is supportive evidence that child-access prevention laws decrease firearm homicides or firearm assault injuries among young people.
Concealed-Carry Laws	No studies met our criteria.	There is inconclusive evidence for how concealed-carry laws affect gun industry outcomes.	No studies met our criteria.	There is inconclusive evidence for how concealed-carry laws affect mass shootings.	There is limited evidence that concealed-carry laws increase fatal police shootings of civilians.	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 supportive evidence that shall-issue concealed-carry laws increase total homicides and firearm homicides.
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.	There is inconclusive evidence for how gun-free zones affect violent crime.
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 gun industry outcomes.	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.

Gun Policy Research Review

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

Policies Regulating Firearm Sales and Transfers

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

Key Findings on Gun Policy in America

Firearm Injury Hospitalizations in America

Gun Policy Expert-Opinion Tool