(NewsNation) — The Supreme Court on Friday overturned a Trump-era ban on bump stocks, ruling that the Bureau of Alcohol, Tobacco, Firearms and Explosives exceeded its authority by determining that the gun attachments turn firearms into machine guns.

The case was decided 6-3, with Justice Clarence Thomas writing the majority opinion and Justice Samuel Alito concurring. Justices Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson, the courts three liberals, dissented.

What are bump stocks?

Bump stocks are attachments for semiautomatic rifles to allow them to fire faster. It harnesses energy from the gun’s kickback to allow it to slide back and forth rapidly.

The stock “bumps” between the shooter’s shoulder and the trigger — hence the name — which allows the shooter to fire multiple, rapid shots while holding the trigger down, rather than pulling it multiple times.

A bump stock allows a semiautomatic rifle to fire at close to the same rate as a fully automatic machine gun, which civilians are not allowed to own.

The decision

In the majority opinion, Thomas wrote that a bump stock on a semiautomatic rifle does not mean the weapon meets the definition of a machine gun.

“It cannot fire more than one shot ‘by a single function of the trigger’ and even if it could, it would not do so ‘automatically.’ ATF therefore exceeded its statutory authority by issuing a rule that classifies bump stocks as machineguns,” Thomas wrote.

In a dissent, Sotomayor wrote that the decision ignores the ordinary meaning of the term machine gun and does not meet the definition intended by Congress.

“When I see a bird that walks like a duck, swims like a duck, and quacks like a duck, I call that bird a duck. A bump-stock-equipped semiautomatic rifle fires ‘automatically more than one shot, without manual reloading, by a single function of the trigger.’ Because I, like Congress, call that a machinegun, I respectfully dissent,” she wrote.

Ban followed deadly shooting

The decision reverses a rule put in place by former President Donald Trump’s administration, one of the few gun control restrictions enacted in the last few years.

The ATF had previously said bump stocks did not qualify but changed the rule following a 2017 shooting in Las Vegas, the deadliest in U.S. history.

A gunman opened fire on the Route 91 Harvest music festival from his hotel room, killing 58 people and wounding more than 400. Many were injured after the crowd began to panic and disperse, trampling over each other. Two more people died in the days and years after the shooting, bringing the total death toll to 60.

Several of the guns used by the perpetrator had bump stocks, leading to the ban.

Read the full decision: