What happened the last time the US banned some semi-automatic guns

Since the Feb. 14 mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, renewed calls for a ban on semi-automatic weapons, such as the AR-15 used in the Florida massacre, are emerging.

On Feb. 22, Sen. Dianne Feinstein called for a hearing on the Assault Weapons Ban of 2017, which would ban the future sale of many semi-automatic weapons. A majority of the American public would support such a ban. According to a Quinnipiac poll released on Feb. 20, 67% of respondents supported a nationwide ban on the sale of assault weapons. And some are already taking action on relinquishing their own gun supply in the wake of the Parkland shooting.

A fresh ban on assault weapons wouldn’t be the first time the firearms were restricted. An assault weapons ban was previously in place from 1994 through 2004 under the Violent Crime Control and Law Enforcement Act of 1994, and while the 10-year ban wasn’t exactly a resounding success, there are signs that it had a positive effect that could be replicated, or even improved, if it were returned.

What did the 1994 assault weapons ban do?

The 1994 assault weapons ban restricted the “manufacture, transfer and possession” of certain semi-automatic weapons, as well as large capacity magazines that hold more than 10 rounds of ammunition.

A 2004 University of Pennsylvania study on the ban for the U.S. Department of Justice noted that it was directed at semi-automatic weapons largely used by the military and for “criminal applications.” The study noted that they are “unnecessary in shooting sports or self-defense.”

The AR-15 used in the Parkland shooting was one of the firearms included in the ban. In 1998, the Penn study noted, the Clinton administration expanded the ban to include a prohibition on importing an additional 58 foreign semi-automatic rifles.

Though the ban applied to many semi-automatic firearms, there were some important loopholes. It contained a “features test” provision which specifically prohibited semi-automatic weapons containing two or more military-style features, such as a folding or telescoping stock and a flash hider. As a result, gun manufacturers could — and did — make minor cosmetic changes that removed the features to transform banned firearms into legal ones.

Most crucially, the ban contained a grandfather clause that allowed the possession and transfer of any semi-automatic weapons or large capacity magazines manufactured before the ban took effect in 1994. Gun manufacturers ramped up their production of the soon-to-be-banned firearms before the ban began. According to the UPenn study, there were approximately 1 million privately owned assault weapons in the U.S. as of 1990, with an additional half-million manufactured between 1989 and 1993. There were also approximately 25 million pre-ban large capacity magazines in the U.S. as of 1995, and an additional 4.8 million were legally imported into the country under the grandfather clause between 1994 and 2000.

The new version of the ban now under consideration, which was introduced in the Senate in 2017, is in many ways similar to the 1994 legislation. According to a statement on the legislation released by Feinstein, the 2017 ban would apply to the “sale, manufacture, transfer and importation” of 205 specific military-style assault weapons, as well as any firearm that accepts a detachable ammunition magazine and has one or more military characteristics.

The ban would also apply to magazines holding more than 10 rounds of ammunition, including banning the transfer of such magazines. The legislation would also ban bump stocks and similar devices that allow a semi-automatic weapon to mimic the functionality of an automatic weapon.

Much like the 1994 ban, the current proposed ban “exempts all weapons lawfully possessed at the date of enactment,” though it requires all grandfathered weapons to be stored “using a secure gun storage or safety device like a trigger lock” and mandates background checks for any “future sale, trade or gifting” of firearms banned under the bill. The ban would also exempt more than 2,200 specific firearms for “hunting, household defense or recreational purposes.”

Was the 1994 ban effective?

Thanks to the grandfather clause, and the relatively low number of total crimes committed using the then-banned firearms — approximately 2% of crimes prior to the ban — the UPenn study found it difficult to conclude whether or not the 1994 assault weapons ban had a demonstrable impact on reducing gun violence.

The ban’s success in reducing crimes was mixed, according to the UPenn study. The share of overall gun crimes involving assault weapons in cities tracked by the study did decline by 17%, to 72% after the ban took effect. The drop in assault weapon-based crime, however, was offset by a rise in the use of other guns that were equipped with large capacity magazines and had been grandfathered in under the ban.

“Because the ban has not yet reduced the use of [large capacity magazines] in crime, we cannot clearly credit the ban with any of the nation’s recent drop in gun violence,” the study noted. “However, the ban’s exemption of millions of pre-ban [assault weapons] and LCMs ensured that the effects of the law would occur only gradually. Those effects are still unfolding and may not be fully felt for several years into the future.”

A 2011 Washington Post analysis found that the assault weapons ban did appear to have an effect in Virginia, where the number of guns with high-capacity magazines seized by police dropped during the 10-year ban period to a low of 10% of all recovered weapons in 2004. This rebounded once the ban was repealed.

When it comes to mass shootings, analyses have also suggested that the assault weapons ban could have had a larger effect. A study published by the Princeton Election Consortium in 2012 found that the assault weapons ban period was overall “peaceful by U.S. standards” in terms of mass shootings. A total of 16 mass shootings took place from 1995 to 2004 in the U.S., with an average of 20.9 people shot in mass shootings each year, as compared with 27 mass shootings from 2005-2012 and an average of 54.8 people shot each year.

A separate study conducted by Louis Klarevas of the University of Massachusetts at Boston for his 2016 book Rampage Nation also found a link between the assault weapons ban and a drop in mass shootings, the Washington Post reported. According to Klarevas’ analysis, the number of gun massacres fell by 37% from 1994 to 2004, as compared with 1984 to 1994, and the number of deaths in gun massacres dropped by 43%. After the ban was repealed, the number of massacres then rapidly increased by 183% from 2004 to 2014, with a 239% increase in mass shooting deaths.

Though it’s unclear whether the drop in mass shootings was directly related to the assault weapons ban, there are signs that an assault weapons ban could reduce such large-scale tragedies. A CNN analysis found that states with a restriction on large capacity magazines had a 63% lower rate of mass shootings. Michael Siegel, a community health science professor at Boston University who conducted the analysis, commented that whether or not the state had such a policy was “the single best predictor of the mass shooting rate in that state.”

While assault weapons may be used in a small percentage of overall crimes, as the Penn study noted, they also make up a larger share of weapons used in mass shootings. A Mother Jones review of 62 mass shootings between 1982 and 2012 found that out of 143 total weapons used, 48 of them would have been banned under an assault weapons ban. Such incidents are also often deadlier; an Everytown for Gun Safety study cited by the Giffords Law Center found that 155% more people are shot and 47% more people are killed in gun incidents that use assault weapons or large capacity magazines as compared with other gun incidents.

An assault weapons ban, particularly with a grandfather clause, wouldn’t be a perfect solution to preventing gun violence. Experts agree, however, that enacting such a law again would still have a positive effect. The New York Times published an analysis into the effectiveness of various gun policies on preventing mass shootings in 2017, based on the opinions of 32 gun policy experts. Of the policies surveyed, bans on assault weapons and high-capacity magazines were considered to be the most effective, receiving effectiveness scores of 6.8 on a scale from one to 10.

Despite the Penn study’s tepid findings, its lead author, Christopher S. Koper, said at a 2013 Summit on Reducing Gun Violence in America at Johns Hopkins University that an assault weapons ban, if left in place for a longer period of time, “could potentially produce at least a small reduction in shootings.” Even a small reduction, Koper noted, would have “nontrivial, notable benefits for society” — using then-current gun statistics, Koper projected that even a 1% reduction in fatal and non-fatal criminal shootings would prevent approximately 650 shootings each year.

“This bill won’t stop every mass shooting, but it will begin removing these weapons of war from our streets,” Feinstein acknowledged in a statement announcing the 2017 assault weapons ban. “Yes, it will be a long process to reduce the massive supply of these assault weapons in our country, but we’ve got to start somewhere.”