Stanford Law Professor John Donohue III says a background check system that was universal and effectively operated could impede gun acquisition by people who commit mass shootings.

Stricter gun laws, especially background checks for buyers who are mentally ill or have engaged in criminal misconduct, could help reduce the frequency of mass shooting tragedies, a Stanford law professor says.

John J. Donohue III, the C. Wendell and Edith M. Carlsmith Professor of Law at Stanford, has been conducting empirical research on gun violence and gun control over the last 25 years. He has written on issues such as whether widespread gun ownership makes people safer and how U.S. gun control compares to the rest of the world. Stanford News Service recently interviewed Donohue about the issue.

How much gun violence is there in the United States, and how do we compare with other countries?

The U.S. dominates the world in number of guns per capita in civilian hands and dominates the affluent countries in rates of gun homicide, overall gun violence, suicides and accidents. The National Rifle Association tries to muddy this comparison by saying that many countries have higher rates of violence than the U.S., but that is only true if you bring in poor countries with weak criminal justice regimes and unstable governments such as Honduras, Guatemala, Yemen, etc.

What do the polls say about Americans’ attitudes toward guns?

Americans have very conflicted views on guns with some thinking they are among the most desirable and important consumer products and an important protection against criminals and a potentially tyrannical government. According to the General Social Survey, roughly one-third of American households have guns, so this is presumably the most pro-gun portion of the population.

Conversely, most Americans do not value hunting or target shooting and for this group, a gun only makes sense if it confers protective benefits that are greater than its costs. For individuals who face a particularly high risk and who are well trained in handling firearms, the benefits of gun ownership can outweigh the risks. For most Americans who don’t hunt or target shoot, though, the risk-reward tradeoff of guns is not favorable. Many Americans in this group think the chance that private gun ownership could pose a meaningful check on government is ludicrous. Moreover, while one can clearly find instances where gun defense was helpful in confronting a criminal, in 99.2 percent of violent crimes in the U.S., the victims do not use a gun in self-defense.

What gun control laws need to be changed or enacted due to terrorist shootings like the one in San Bernardino?

Gun policy should not be made based on a single incident but rather from a careful evaluation of the costs and benefits of particular legal interventions in light of all the evidence on mass shootings, on ordinary crime, as well as data on gun suicides and accidents. Since it has been federal policy for decades to try to keep guns out of the hands of criminals and the severely mentally ill, universal background checks are an obvious first step. Indeed, looking at recent episodes of mass shootings, one sees time and again that a background check system that was universal and effectively operated would impede gun acquisition by the mass shooters.

For example, Dylan Roof should have been precluded by virtue of a recent drug arrest from buying the gun he used shortly thereafter to kill nine church members in South Carolina in June 2015. But gun lobby pressure has led to the unwise rule that forces the sale to proceed after three days, even if that has been an inadequate time to validate whether the purchase is lawful. Aaron Alexis, who killed 12 in 2013 at the Washington Navy Yard, had a record of criminal misconduct and mental illness that easily would have been disqualifying with a strengthened background check system that captured the relevant data known to police prior to his rampage. The same can be said about the recent crazed shooter at the Planned Parenthood facility in Colorado Springs.

Thirty-three died at Virginia Tech in 2007 after the state’s database failed to reflect the serious mental illness of Seung-Hui Cho. Current law clearly prohibited him from purchasing guns, but without an effectively functioning background check system such laws are useless. From the Gabby Giffords shooting in Arizona to the Batman movie theater shooting in Colorado, disaster strikes when guns end up in the hands of deeply troubled individuals. Bringing federal law in line with common sense rules on gun possession would clearly help in reducing mass shootings.

We would be in a better place today in dealing with these mass shootings if the assault weapons ban that lapsed in 2004 had remained in effect. The 10-round limitation on high-capacity magazines was unambiguously advantageous, and with a law in place, efforts to limit the power and lethality of weapons in a rational and societally beneficial way could be more readily undertaken.

What legislatively could be done to reduce gun violence overall?

In addition to safe-storage laws, everything already mentioned would have a beneficial effect on gun violence. The best evidence to date suggests that right-to-carry laws increase gun violence, so efforts to eliminate or tighten those laws and to oppose their adoption in the states that do have them would be prudent at this time. A recent study noted that since May 2007, 29 concealed carry permit holders have gone on shooting sprees that killed at least three individuals. In general, legislative tightening of those allowed to possess guns to the fullest extent that the Constitution allows is clearly worth exploring.

Of course, many other measures beyond gun control could reduce crime in general, although at various levels of cost: legalizing drugs, improvements in the number and quality of police, pre-school enrichment programs, facilitating family planning, etc. Note that private citizens spend billions of dollars each year to purchase guns for self-defense when far greater reductions in crime could be achieved if those resources were instead devoted to the most productive and efficient crime-fighting measures.

Watch a Stanford Law School video of John Donohue discussing guns and crime.

This Q&A was published by the Stanford Report on December 31, 2015.