The Federal Assault Weapons Ban (FAWB) prevented up to five public mass shootings when it was active between 1994 and 2004, according to previous research. A new Northwestern Medicine study has found that had the ban remained in place, it would have prevented up to 38 more mass shootings between 2005 and 2022.
Enacted by Congress in 1994, the ban prohibited the sale and manufacture of certain military-style semiautomatic weapons and high-capacity magazines in the U.S. Despite multiple attempts, efforts to renew the ban have not succeeded.
Most research has focused on whether the number of mass-shooting deaths declined during the FAWB. This is the first study to consider how many mass shootings would have been prevented had the ban remained in place.
“It is intuitive that shooters with rapid-firing, machine-gun-like military weapons with large-capacity magazines can quickly fire and kill or injure dozens of people in just seconds compared to shooters with pistols, revolvers, rifles or shotguns,” said senior author Lori Post, professor of emergency medicine and medical social sciences at Northwestern University Feinberg School of Medicine. “However, there are only two investigations into whether a prohibition of assault weapons prevents mass shootings from even occurring. It certainly does.”
The findings were published Sept. 20 in the journal JMIR Public Health and Surveillance.
“Nobody wants to be a victim of these seemingly random events, and nobody wants to worry that their children are going to die at school,” Post said. “Most Americans, despite political affiliation, believe in responsible gun ownership. We need to prevent mass shooter wannabees from obtaining assault rifles — because many need an assault rifle to carry out the mass shooting.”
The study found that FAWB was successful at stopping potential mass shooters from committing a mass shooting. It also demonstrates that would-be mass shooters did not substitute other weapons for assault weapons and large-capacity magazines, as those types of mass shootings did not change during the assault weapons ban.
“One of the more interesting parts of this work is the separation of results into mass shootings where the shooter did or did not bring an assault weapon to the event,” said first author Alexander Lundberg, assistant professor of emergency medicine at Feinberg. “During the FAWB, we found a downward trend in mass shootings where a perpetrator did bring an assault weapon. However, we found no difference in trends for mass shootings where the perpetrator did not bring an assault weapon. These results suggest that FAWB discouraged potential perpetrators from committing a mass shooting with an assault weapon and furthermore that these potential perpetrators did not simply carry out attacks with other types of weapons.”
The scientists define a public mass shooting as an event in a public place where there are at least four people killed by a firearm within a 24-hour time period. Using this definition, they included all public mass shootings (a total of 184) that occurred between 1966 (when the FBI began tracking them) and 2022. The researchers used linear regression on a simple moving average of mass shootings per year while controlling for national homicide rates.
Given that many people have purchased assault weapons over the past two decades since FAWB expired, Post noted that any future ban would need either a buyback program or exclusion of a “grandfather” clause.
“We won’t be able to stop all mass shootings — especially those committed by a jilted husband or fired employee who reacts and kills people they know with whatever gun they have,” Post said. “However, a ban on assault weapons and large-capacity magazines would surely thwart mass shootings committed by those who spend weeks planning or want fame through such acts.”
Other study authors from Northwestern include Maryann Mason and David Victorson.
Funding for this study was provided by an anonymous foundation donor.