Which US laws have been shown to cut gun violence and mass shootings?

By Grace Wade

Behavioural scientist Andrew Morral leads the Gun Policy in America initiative at non-profit research institute the RAND corporation. He tells New Scientist why conducting gun violence research in the US has been so difficult, how that is starting to change and what the latest evidence shows about the impact of everything from background checks and safe storage laws to assault weapon bans.

Grace Wade: What interventions work against gun violence?

Andrew Morral: At the Gun Policy in America initiative, we maintain a systematic review of what we know about the effects of gun laws on outcomes including suicide, homicide and mass shootings but also defensive gun use participation, hunting and sport shooting.

We’ve rated child access prevention laws, or safe storage laws, as having the strongest evidence of an effect at reducing firearm suicides and injuries among young people. There’s also moderately good evidence that they reduce firearms casualties, even among older people.

But most states don’t have child access prevention laws. That’s because most people who buy firearms, at least handguns, are buying them for self-protection. They then feel like if they have their gun locked up, they won’t be able to access it in time in an emergency.

That’s one of the reasons safe storage laws don’t pass in many states – fear that there will be a downside to that law. Yet we can’t really evaluate this trade-off because we don’t have good research on defensive gun use.

Do we know which laws make things worse?

We have good evidence on stand your ground laws, but it points to them having a harmful effect. These are associated with increases in firearm homicides.

These laws, which expand the circumstances in which deadly force is permitted in self-defence, have swept the nation in the last decade or two. It used to be that, if you could retreat from a conflict safely, you were not permitted to use deadly force. [Stand your ground laws] relieve people of the duty to retreat.

What about background checks?

There’s moderately good evidence, our second highest rating, that the kind of background checks the federal government requires decrease firearm homicide.

But they only apply to sales of firearms from gun dealers. There are a lot of transactions of firearms between private parties, and they are not subject to background checks in many states.

There have been calls for a federal law requiring universal background checks [for all sales]. These very well may improve upon ones only with dealers, but there just isn’t great research on that yet.

What are red flag laws, and do they work?

They are different in different states, but they apply to people who appear to present a risk to themselves or others. The petition for a red flag order or extreme risk protection order could be made by people such as a family member, law enforcement or mental health professional.

A judge then determines whether that person should not be allowed to have a firearm. The laws are very time limited, 16 days in some cases. It’s not a permanent injunction, it’s an emergency measure.

We don’t have studies that make an open-and-shut case that they’re effective because they just haven’t been around long enough to get that kind of evidence.

But there was a really interesting study by Garen Wintemute at the University of California, Davis, [looking at whether these laws can reduce mass shootings]. It included 21 case studies where red flag orders were used. From that anecdotal evidence, it looks like they might have some real benefits. But in terms of studies we would classify as providing strong causal evidence, those haven’t been done yet.

Do assault weapon bans prevent gun-related deaths?

The short answer is we don’t have strong evidence, but that’s largely because it’s really hard to study. Mass shootings are very rare and [statistically] it’s a very noisy time series. There have been studies, but they have very weak statistical power; they didn’t stand a chance of showing anything from the start.

I think it’s very possible they would have an effect on mass shootings – or at least [on the number of] casualties in mass shootings.

Are there any interventions around mental health that make a difference?

This is a tricky topic, but one of the things that seems most clear is that people with serious mental health conditions are much more likely to be victims of violence.

You could argue that a better indicator of killing a lot of people is being a man, because it’s almost exclusively men who do this.

For nearly 25 years, the US government didn’t fund gun violence research. Why not?

In the mid-1990s, the US Centers for Disease Control and Prevention conducted research on gun violence prevention. Some people felt that it was advocating for gun control.

The CDC didn’t see it that way, but Congress passed the Dickey Amendment in 1996, which said that advocacy research couldn’t be done on this topic. It also withdrew funding from the CDC in the amount equivalent to how much it had been spending on firearms violence prevention. [These restrictions] were expanded to include the National Institutes of Health in 2012.

For almost a quarter of a century, very little research on firearms violence was supported by the federal government.

One study has shown that, compared to what you would expect to see in federal funding given how many people die from firearms violence compared to other causes of death, just 1.6 per cent was spent.

Now there is government funding though…

The Dickey Amendment has not gone away, but Congress has clarified its intention and appropriated funds for research on firearms violence.

I take some personal credit for this because I was testifying at the appropriations hearing and I made the case to the committee that you could keep the Dickey Amendment and use it as a guard rail – an idea first suggested to me by Mark Rosenberg, director of the CDC’s National Center for Injury Prevention and Control when the Dickey Amendment was passed. The committee eventually supported the appropriation.

The first funding went out in 2020, and that moderately small programme – $ 25 million a year – has been kept alive for three years now.

What are the gaps in our knowledge about gun violence?

Even when the federal government wasn’t supporting it, there was some good research going on – but nothing like the level you would expect, given how serious a problem this is.

Also, the federal government wasn’t collecting the kind of data needed to do a lot of this work. As of a couple years ago, though, the government has fully funded the CDC’s National Violent Death Reporting System. So, that’s a really big change and a positive one.

Other things are going backwards. The FBI has stopped reporting uniform crime data, so we’ve lost a more than 30-year time series.

There’s good data that the government collects on firearm injuries that result in hospitalisations or emergency room treatment but it’s prohibitively expensive for researchers to get their hands on.

And since 2003, the Tiahrt Amendment also made it so that the Bureau of Alcohol, Tobacco, Firearms and Explosives couldn’t share gun trace data in the way that it had been, and that’s closed off a lot of important research. That remains fully in effect.

How is the research now changing?

The big changes recently have been an influx of both private and federal dollars that have allowed a whole bunch of projects to start up. I’m director of the National Collaborative on Gun Violence Research and, since 2018, we have given almost $22 million in funding to more than 44 projects.

Between the CDC and the NIH, the federal government has funded about 45 or 50 projects at this point.

It’s a time of growth in this field. A lot of people want to help with this problem, want to understand it better and investigate potential solutions.

How does the conversation around gun violence in the US need to change?

Guns are among the most polarising policy questions that we have today. A lot of people have very entrenched views. They’re not particularly open to new evidence and that’s a real problem on both sides of this debate – and I really do mean both sides, at the extremes.

I think there’s a large middle ground in the country of people who really just want solutions and they’re open to new information, research and evidence. My hope is that the middle group will be large enough and persuaded enough by good policy options to move the policy needle toward better prevention.

This interview has been edited for continuity and length.

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