Recent mass shootings have revived demands for meaningful gun control. But many opponents of a renewed federal ban on assault weapons, led by the National Rifle Association, say the earlier ban, from 1994 to 2004, made no difference. Our new research shows otherwise.
We found that public mass shootings — which we defined as incidents in which a gunman killed at least six people in public — dropped during the decade of the federal ban. Yet, in the 15 years since the ban ended, the trajectory of gun massacres has been sharply upward, largely tracking the growth in ownership of military-style weapons and high-capacity magazines.
Using the Mother Jones mass shooting database, we identified the number of gun massacres over a 35-year period. (And following the F.B.I.’s approach, we excluded crimes of armed robbery and gang or domestic violence in evaluating public active shooter incidents.) Compared with the decade before its adoption, the federal assault weapon ban in effect from September 1994 through 2004 was associated with a 25 percent drop in gun massacres (from eight to six) and a 40 percent drop in fatalities (from 81 to 49).
This decline is plausible because assault weapons are semiautomatic firearms designed for rapid fire and combat use, and large-capacity magazines increase the number of rounds that can be fired without reloading. While the gun lobby prevented the ban from being as effective as it could have been and saddled the law with a 10-year sunset provision, the ban did impede the easy access to the type of lethal weaponry that those intent on mass killing have readily available in most of the country today. (Assault weapons are legal in 43 states; large-capacity magazines, commonly understood as ammunition-feeding devices holding more than 10 rounds, are legal in 41.)
The first studies of the law’s effectiveness were inconclusive. For example, it was initially unclear whether a decline in gun massacres and deaths was simply part of a larger drop in crime, since violent crime declined by roughly 14 percent during the federal ban.
But data from the 15 years following the ban’s expiration now provide stronger evidence that permitting the gun industry to flood the market with increasingly powerful weapons that allow for faster killing has facilitated exactly that outcome. In the decade after the ban, there was a 347 percent increase in fatalities in gun massacres, even as overall violent crime continued downward.
Indeed, the number of gun-massacre fatalities in the past five years alone has already topped the previous high for the decade after the ban was lifted. If we continue at the post-2014 pace, by 2024 we will have had more than 10 times as many gun massacre deaths in that 10-year period as we had during the decade of the federal assault weapons ban.
Similarly, fatalities per shooting incident fell during the assault weapon ban and have risen sharply since. With increasingly potent and readily available weaponry, the average number of people who die in a gun massacre has increased by 81 percent in just five years. Assault weapons were used in at least 11 of the 15 gun massacres since 2014; at least 234 of the 271 people who died in gun massacres since 2014 were killed by weapons prohibited under the federal assault weapons ban.
And despite what critics of gun control may assert, mental illness is not driving the alarming growth in fatalities from gun massacres. The percentage of mentally ill Americans did not drop substantially during the 10 years of the federal ban and then suddenly rise rapidly when it was lifted.
Gun industry advertisements play on the weaknesses of troubled young men, persuading them that their perceived grievances could be remedied if they possessed the latest assault weapons. The deeply troubled 20-year-old Adam Lanza used a semiautomatic Bushmaster rifle — advertised under the slogan “Consider Your Man Card Reissued” — to kill 26 at Sandy Hook Elementary School in 2012. No other industry is allowed to act so recklessly without facing legal challenge. But a 2005 law immunized gun manufacturers against lawsuits for harm caused by the criminal use of firearms.
The 19-year-old killer of 17 at Parkland High School and the recent Dayton shooter possessed traits that would have disqualified them in many other countries from access to any firearm, let alone a military-style weapon. Numerous steps need to be taken if our mass shooting problem is to be effectively addressed.
There is no reason to think that this ghastly trend will abate without concerted government effort. We should enact a comprehensive federal assault weapons ban and limit on high-capacity magazines, repeal the federal immunity statute and create a more comprehensive and effective background check and red-flag system to ensure that the growing power of advanced weaponry is not readily available to dangerous individuals.
Senator Dianne Feinstein of California, pivotal in getting the first ban through Congress, is among the many Democrats — both presidential candidates and on Capitol Hill — who are pressing to reinstate it or enact a new one. Strong majorities of Americans favor such a ban.
But President Trump and Republicans, who hold the majority in the Senate, strongly oppose this. And the N.R.A. has initiated lawsuits across the country to overturn existing state bans on assault weapons and high-capacity magazines. It also wants the Supreme Court — enriched by two Trump appointees — to effectively end all serious gun safety measures by inflicting an extreme interpretation of the Second Amendment.
The Supreme Court should heed the words of the conservative Reagan appointee Judge J. Harvie Wilkinson when the United States Court of Appeals for the Fourth Circuit voted to uphold the Maryland assault weapons ban:
“To say in the wake of so many mass shootings in so many localities across this country that the people themselves are now to be rendered newly powerless, that all they can do is stand by and watch as federal courts design their destiny — this would deliver a body blow to democracy.”
The extraordinary increase in the body count from public gun massacres since the end of the federal assault weapons ban and the passage of the federal immunity statute for the gun industry has one obvious explanation: the brazen promotion and the proliferating, loosely regulated, highly profitable sales of the most desirable and effective weaponry for committing mass murder.
While there are certainly considerable political risks in pursuing gun safety measures, if the goal is to save lives, it is time to turn in earnest to the task generations of graduating law students have been directed to undertake: “the shaping and application of those wise restraints that make men free.”
John Donohue is a law professor at Stanford Law School. Theodora Boulouta is a senior at Stanford.
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