Alito says he's sure Congress wanted to ban a rapid-fire gun device, but sided with the ruling to overturn the ban anyway

• The Supreme Court threw out a ban on bump-stock devices.
• The devices allow rifles to fire bullets quickly and were used in the 2017 Las Vegas mass shooting.

There's "little doubt," Supreme Court Justice Samuel Alito wrote, that Congress would have considered bump stocks akin to a machine gun.

The devices — which allow semiautomatic rifles to fire bullets at nearly the rate of machine guns — were banned by federal authorities in 2018 after the Las Vegas mass shooter used them to kill 60 people and wound over 400 more.

But Alito and the other conservative justices still ruled to throw out the ban, saying the text of Congress' definition of machine guns —which the ban was based on — wasn't explicit enough.

"The statutory text is clear, and we must follow it," the textualist justice wrote.

The Supreme Court on Friday struck down the Bureau of Alcohol, Tobacco, Firearms and Explosives rule that classified bump stocks as "machine guns."

The devices use a gun's recoil to reactivate the trigger faster, allowing weapons to be fired at upward of 800 rounds a minute.

The ATF had previously allowed the devices but reclassified them during the Trump administration after the carnage of the October 1, 2017, shooting, in which the gunman fired down from a nearby hotel at concertgoers at a country-music festival.

But Michael Cargill, a gun-shop owner from Austin, sued the federal government. He argued it had been too broad in interpreting firearms law and that Congress never explicitly meant to ban bump stocks, challenging the law on statutory grounds, not Second Amendment protections.

In its decision Friday, the court's conservative justices agreed.

Writing for the majority opinion, Justice Clarence Thomas said that a bump stock couldn't be considered a machine gun because it doesn't fire more than one bullet per trigger pull — it accelerates how many times the trigger is pulled.

"A bump stock does not convert a semi-automatic rifle into a machinegun any more than a shooter with a lightning-fast trigger finger does," Thomas wrote.

In his opinion, in agreement with Thomas, Alito said the "horrible shooting spree" in Las Vegas proved that a bump stock could cause the same kind of killing as a machine gun.

But he said Congress needed to be explicit that it wanted to ban bump stocks, too, by amending the law or passing a new one.

"Now that the situation is clear, Congress can act," Alito said.

In a dissenting opinion joined by the other liberal members of the court, Justice Sonia Sotomayor trashed the decision as "artificially narrow" and said it would have "deadly consequences."

"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," she wrote.