The Washington PostDemocracy Dies in Darkness

Researchers reviewed thousands of gun policy studies and teased out a consensus

The findings on stand-your-ground and child access prevention laws are conclusive, the report says

Mayor Muriel E. Bowser (D) held a news conference earlier this year to announce legislation to ban the import of kits and parts used to make untraceable “ghost guns.” (Astrid Riecken for The Washington Post)

Gun control discussions often get mired in competing academic claims regarding the effectiveness, or lack thereof, of various policy options.

Do concealed carry laws increase violent crime or make communities safer? Do assault weapon bans reduce mass shootings or do they have no effect? Do background checks reduce homicides and suicides or are they ineffective?

With so many disparate findings swirling about, it can be difficult to determine where the balance of evidence lies. But a report from Rand Corp., a nonprofit think tank, has distilled reams of gun policy research published since 1995 to tease out the scholarly consensus.

In other words, they’ve waded through thousands of findings so you (and your elected representatives) don’t have to.

Not all academic studies are created equal. Many simply show correlations between various phenomena — links between assault weapon bans and mass shootings, for instance, or between suicide rates and gun purchasing habits. Such research can be useful when higher-quality data isn’t available.

But policymaking requires higher-caliber evidence, from studies that go beyond simple correlations to demonstrate a causal effect. Distinguishing those studies from less-powerful ones was one of the chief objectives of the Rand report.

“For our analysis, we looked for studies that made stronger claims to identifying a causal effect of individual laws,” said Andrew Morral, one of the authors of the report. “They had to show that changes (for instance, in suicide rates) that are attributed to the law occurred only after the law was implemented (not before), and did not occur in states where the law was not implemented.”

They narrowed down thousands of studies to those that met high standards for causal evidence — just 123 of them since 1995. Taken together, this research yielded a number of conclusions.

First, there was a clear consensus (indicated by three or more high-quality studies in agreement) that stand-your-ground laws, which allow people to use guns to defend themselves in public even if retreating is an option, result in higher overall rates of gun homicide. The higher rates aren’t simply from “bad guys” getting shot; the research shows the additional deaths created by stand-your-ground laws far surpass the documented cases of defensive gun use in the United States.

There was also a broad consensus that child access prevention laws, which set requirements for how guns must be stored at home, are effective in reducing self-inflicted gun injuries among children and adults.

No other policy realm showed the clear scholarly consensus as did stand-your-ground and child access prevention, although there were a number of cases in which the research yielded more moderate evidence of a policy’s effect, by way of two or more high-quality studies in agreement.

For instance, there is moderate evidence that banning gun purchases by people under domestic violence restraining orders decreases intimate-partner homicides. The research also showed moderate evidence that background checks reduce gun homicides, and that waiting periods for firearms purchases reduce gun suicides and overall homicide.

Finally, there was what the authors call “limited” evidence — just one high-quality study, not contradicted by other research — for a number of policy outcomes. There’s some evidence, for instance, that licensing requirements reduce suicides, that bans on gun ownership among the mentally ill reduce violent crime, that “right-to-carry” laws increase violent crime, that minimum purchasing age requirements reduce youth suicides, and that assault weapon bans end up boosting sales of those weapons in the period before the ban takes place.

Beyond that, the available high-quality research remains inconsistent or nonexistent. There is no scholarly consensus, for instance, on the effect of assault weapon bans on mass shooting rates, or on the overall effects of extreme risk prevention (“red flag”) laws. There similarly is little to no evidence on the efficacy of mandatory gun-safety training. High-quality research into gun-free zones and armed school employees is nonexistent, and there’s virtually no good research examining effects of policies on defensive gun use.

That general lack of high-quality evidence is one of the overarching themes of the report. “One reason there is such limited and inconclusive research on topics related to gun policy is that the federal government has not supported much research on gun violence prevention for most of the last 25 years,” Morral said. But he notes that last year Congress approved the first outlay of federal money for gun research since the mid-1990s.