In this Oct. 4, 2017 file photo, a device called a “bump stock” is attached to a semi-automatic rifle at the Gun Vault store and shooting range in South Jordan, Utah. The U.S. Supreme Court overturned a Trump-era federal ban on bump stocks. Following the 2019 ban, tens of thousands of the devices were destroyed by owners or handed over to authorities.

Rick Bowmer/AP

hide caption

toggle caption

Rick Bowmer/AP

The U.S. Supreme Court today overturned a federal ban on bump stocks, the devices that can attach to a semi-automatic rifle to make it fire as fast as a machine gun — potentially hundreds of rounds a minute.

Machine guns have been effectively banned for most people since the 1930s, but there have been doubts about whether that ban applies to attachments that can make legal guns shoot as fast as a machine gun. The Bureau of Alcohol, Tobacco, Firearms and Explosives determines that, and over the years the agency went back and forth over whether to ban bump stocks. But in 2017, a man using bump stocks committed the deadliest gun massacre in modern American history, killing 60 people and injuring hundreds at a Las Vegas concert. After that mass shooting, many bump stock owners saw a ban coming. The Trump Administration then indeed moved to ban bump stocks, a restriction that took effect in 2019.

What was the court’s reasoning to lift that ban?

It all comes down to the law’s definition of machine gun, which says it’s a gun that fires multiple rounds with “a single function of the trigger.” That word “function” is key here, as it’s not the same as a pull of the trigger.

With a bump stock, you pull the trigger once, holding it, bracing the stock against your shoulder while the recoil moves the trigger for you very rapidly, firing those rounds at machine-gun speeds; one pull, but multiple trigger functions.

What the court said today is that’s a big enough difference that the ATF was wrong to call a bump stock a “machine gun” as defined by the law.

That seems to be a very technical distinction. Could this end up permitting other kinds of gun attachments?

Probably not directly because it’s so narrowly focused on the mechanics of bump stocks, so it wouldn’t apply to, for instance, Glock switches, which are a different kind of illegal device that allows a handgun to shoot like an automatic, according to Adam Skaggs, chief counsel with Giffords Law, a gun safety group. He is, however, worried about the Supreme Court’s broader approach here.

“I think, though, the fact that there are six justices that are willing to cavalierly toss aside an incredibly important public safety regulation by the ATF suggests they may look at other regulations by the ATF with skepticism,” he says.

What about gun rights lawyers? Do they think this ruling will affect other firearms restrictions?

Attorney Matt Larosiere, who helped bring a similar challenge to the bump stock ban, agrees this shouldn’t affect the ban on Glock switches, or auto sears, but he thinks it could affect other ATF regulations, such as the ban on guns without serial numbers, known as “ghost guns.”

“What this case is about isn’t so much the definition of machine guns, but it’s about how far outside the lines the Supreme Court is willing to allow the regulatory agencies to draw. And I think what this case is saying is, ‘not very far.'”

What about states that already have bump stock bans in place?

At least 15 states and the District of Columbia prohibit bump stocks. This isn’t a Second Amendment ruling, so it doesn’t overturn state bans. The Supreme Court says Congress, if it chooses, could always pass a law changing the definition of machine guns to include bump stocks.