FactChecking Biden’s Claim that Assault Weapons Ban Worked

President Joe Biden claims the 10-year assault weapons ban that he helped shepherd through the Senate as part of the 1994 crime bill “brought down these mass killings.” But the raw numbers, when adjusted for population and other factors, aren’t so clear on that.

There is, however, growing evidence that bans on large-capacity magazines, in particular, might reduce the number of those killed and injured in mass public shootings.

A day after the Boulder, Colorado, mass shooting, in which 10 people were killed by a gunman in a grocery store on March 22, Biden spoke in support of two House-approved bills that would expand background checks to include private sales. Biden also returned to another campaign promise on gun control: to ban assault weapons and high-capacity magazines.

“We can ban assault weapons and high-capacity magazines in this country, once again,” Biden said. “I got that done when I was a senator. It passed. It was a law for the longest time and it brought down these mass killings. We should do it again.”

Biden is referring to his work as chairman of the Senate Judiciary Committee when he sponsored and largely shepherded the Violent Crime Control and Law Enforcement Act into law in 1994. That law, among other things, included an “assault weapons” ban, which prohibited the sale of certain semiautomatic firearms and large-capacity magazines that could accommodate 10 rounds or more. (Existing weapons on the banned list were “grandfathered,” meaning people could keep them.) A sunset provision, however, meant that the ban expired in 10 years, in 2004.

We wrote about this issue eight years ago, when the gun debate was again raging in Congress. At the time, we found that a three-part study funded by the Department of Justice concluded that the ban’s success in reducing crimes committed with banned guns was “mixed.”

We wrote:

FactCheck.org, Feb. 1, 2013: The final report concluded the ban’s success in reducing crimes committed with banned guns was “mixed.” Gun crimes involving assault weapons declined. However, that decline was “offset throughout at least the late 1990s by steady or rising use of other guns equipped with [large-capacity magazines].”

Ultimately, the research concluded that it was “premature to make definitive assessments of the ban’s impact on gun crime,” largely because the law’s grandfathering of millions of pre-ban assault weapons and large-capacity magazines “ensured that the effects of the law would occur only gradually” and were “still unfolding” when the ban expired in 2004.

Recent Research 

Some things haven’t changed much since then. A RAND review of gun studies, updated in 2020, concluded there is “inconclusive evidence for the effect of assault weapon bans on mass shootings.”

“We don’t think there are great studies available yet to state the effectiveness of assault weapons bans,” Andrew Morral, a RAND senior behavioral scientist who led the project, told FactCheck.org in a phone interview. “That’s not to say they aren’t effective. The research we reviewed doesn’t provide compelling evidence one way or the other.”

There has, however, been emerging research about post-ban trends that may provide information that could be useful to evaluating what worked and what didn’t in the 1994 assault weapons ban.

For example, research published in 2019 in Criminology & Public Policy by Grant Duwe, director of research and evaluation for the Minnesota Department of Corrections, found that after controlling for population growth, the assault weapons ban did not appear to have much of an effect on the number of mass public shootings, comparing a pre-ban period with the 10 years the ban was in effect. But he found that the incidence and severity of mass public shootings, meaning the number killed and injured, has increased over the last decade, after the ban had expired.

Duwe, author of “Mass Murder in the United States: A History, documented 158 mass public shootings in the U.S. between 1976 and 2018, which included shootings that “occur in the absence of other criminal activity (e.g., robberies, drug deals, and gang ‘turf wars’) in which a gun was used to kill four or more victims at a public location within a 24-hour period.”

Duwe also looked at three-, five- and 10-year moving averages to flatten out some of the extreme spikes and dips in individual years.

Duwe found that the lowest 10-year average in mass shooting rates was between 1996-2005, which roughly corresponds with the ban period. But Duwe notes that that “aligns with broader trends observed for crime and violence in the United States.” In other words, it’s hard to know how much the assault weapons ban may have affected mass shootings during that time.

While the incidence rate was higher pre-ban than post-ban, the number of victims killed and shot — the severity of mass public shootings — has increased dramatically in the post-ban period, after 2004, Duwe found.

“The growing number of highly lethal mass public shootings raises several important questions,” Duwe wrote. “Perhaps most notably, why have they become more deadly since the mid-2000s? Is this effect a result of the expiration of the federal assault weapons ban in 2004? Or is it a result of other changes in gun policy?”

Although he poses these questions, Duwe does not offer a definitive conclusion about the impact of the assault weapons ban.

Duwe noted that the relative infrequency with which mass public shootings occur “makes it challenging to predict with accuracy who will commit a mass public shooting or to develop policies designed to reduce their incidence or severity.” And so, he said, it “may be unrealistic to assume that policy proposals targeting mass shootings in particular would, individually or collectively, prevent a catastrophic attack from ever taking place in the future.”

Research published in Criminology & Public Policy in January 2020 concluded that assault weapons bans “do not seem to be associated with the incidence of fatal mass shootings.” However, state laws requiring handgun purchasers to obtain a license and state bans of large-capacity magazines did appear to be “associated with reductions in fatal mass shootings.”

“It’s worth noting that state bans of LCMs were shown to be associated with reductions in fatal mass shootings and state bans of assault weapons were associated with fewer fatal mass shootings, however, the relationship was not statistically significant,” Daniel Webster, one of the authors of the study and director of the Johns Hopkins Center for Gun Policy and Research, told us via email.

“It’s clear that there is an association between weapon features, most notably ammunition capacity, and how many people are shot in these incidents,” Webster added. “Shooters select weapons and ammunition feeding devices that will allow them to shoot as many people as possible. It is a separate question whether bans will reduce casualties from mass shootings or how long they need to be in place in order for the effects to be realized.”

In separate research also published in Criminology & Public Policy in January 2020, Christopher S. Koper, principal fellow of George Mason University’s Center for Evidence-Based Crime Policy and the author of the Department of Justice review of the 1994 assault weapons ban, focused on the role of large-capacity magazines (as opposed to assault weapons) in mass shootings.

“Crimes with AWs [assault weapons] began to decline shortly after the ban’s passage, likely in part because of the interest of collectors and speculators in these weapons, which helped to drive their prices higher through the end of the 1990s (thus making them less accessible and affordable to criminal users),” Koper wrote. “Criminal use of other semiautomatics equipped with LCMs [large-capacity magazines], however, appeared to climb or remain steady through the late 1990s and into the early 2000s, adjusting for overall trends in gun crime. Available evidence suggests that criminal LCM use eventually declined below pre-ban levels but only near the ban’s expiration in 2004. As noted, crimes with LCM firearms have since increased.”

Koper argues that the ““most important provisions of assault weapons law” are restrictions on large-capacity magazines, because “they can produce broader reductions in the overall use of high-capacity semiautomatics that facilitate high-volume gunfire attacks.”

“This rise in LCM use would arguably have not happened, or at least not to the same degree, had Congress extended the ban in 2004,” Koper states. “Considering that mass shootings with high-capacity semiautomatics are considerably more lethal and injurious than other mass shootings, it is reasonable to argue that the federal ban could have prevented some of the recent increase in persons killed and injured in mass shootings had it remained in place.”

Specifically, Koper concluded, “Data on mass shooting incidents suggest these magazine restrictions can potentially reduce mass shooting deaths by 11% to 15% and total victims shot in these incidents by one quarter, likely as upper bounds.”

The success of any ban on assault weapons and large-capacity magazines, Koper said, may depend on how the law is implemented, especially with regard to treatment of pre-ban weapons.

Koper argues that “exemptions and loopholes” in the 1994 assault weapons ban likely blunted the short-term effects of the law. Millions of existing weapons and magazines were “grandfathered,” making them legal to own, and importers were able to import tens of millions of large-capacity magazines manufactured before the ban took effect.

During the campaign, Biden vowed that a new assault weapons ban would be “designed based on lessons learned from the 1994 bans.”

“For example, the ban on assault weapons will be designed to prevent manufacturers from circumventing the law by making minor changes that don’t limit the weapon’s lethality,” according to Biden’s campaign website. “While working to pass this legislation, Biden will also use his executive authority to ban the importation of assault weapons.”

Biden also proposed requiring citizens who own assault weapons to undergo a background check and register those weapons with the Bureau of Alcohol, Tobacco, Firearms and Explosives, as those who currently possess machine guns must do. Machine guns have been banned since 1986, though grandfathered weapons can be transferred from one registered owner to another registered owner.

And finally, Biden said he would institute a voluntary buyback program for existing assault weapons and high-capacity magazines. Those who do not sell their weapons to the government would have to register them.

Although there is broad public support for banning assault-style weapons and high-capacity ammunition magazines (including from about half of Republicans), the proposal does not appear to have the 60 votes needed in the Senate to overcome a potential filibuster.

During a press conference on March 25, Biden did not commit to a timeline for when gun control legislation such as an assault weapons ban might come to the forefront in Congress, saying only that it was “a matter of timing.” Biden said his next big legislative push will be for infrastructure.

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