Supreme Court strikes down Trump-era wholesale stockpile ban

The U.S. Supreme Court on Friday struck down a Trump-era ban on safety stocks, ruling that the Bureau of Alcohol, Tobacco, Firearms and Explosives wrongly classified firearms equipped with a safety stock like machine guns.

The 6-3 opinion was written by Justice Clarence Thomas. The court's three liberal justices, led by Justice Sonia Sotomayor, dissented.

The court ruled that a semi-automatic rifle equipped with a bump stock is not a “machine gun” under federal law “because it does not fire more than one shot” through a single function of the trigger”.

“This case asks whether a bump stock – an accessory for a semi-automatic rifle that allows the shooter to quickly re-engage the trigger (and therefore achieve a high rate of fire) – converts the rifle into a “machine gun.” We We believe this is not the case,” Thomas wrote.

More than 700,000 replacement stocks have been sold since 2009 after the Obama-era ATF approved manufacturing and sale. The stock, which is not mechanical, can simulate an automatic weapon, firing between 400 and 800 rounds per minute. A fully automatic weapon, such as an M16 rifle, fires between 700 and 950 rounds per minute.

The ATF ban on the accessory was created following the deadliest mass shooting in U.S. history, when a gunman opened fire at the Las Vegas music festival in 2017. Fifty-eight people were killed and hundreds more injured.

Sotomayor, in his dissent, noted that the shooter in that tragedy used the device to trigger rapid fire.

“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,” Sotomayor wrote. “A semi-automatic rifle equipped with a stock fires 'automatically more than one shot, without manual reloading, by a single trigger function.'”

Sotomayor added: “Today's decision to reject this ordinary agreement will have deadly consequences. The artificially narrow definition of the majority is crippling the government's efforts to keep the machine guns away from gunmen like the Las Vegas shooter.”

Bump Stock inventor Jeremiah Cottle, who previously spoke to ABC News about his controversial gun accessory, called the court's decision a “good decision” and a personal “vindication.”

“I think we have a violence problem in this country. I don't think we have a gun problem,” Cottle said. “I think it's a balancing act. And I think blaming an inanimate object is irresponsible.”

Plaintiff Michael Cargill, a gun store owner in Texas, told ABC News the case is “not just about guns” but also about government overreach.

“They can't come into my house and tell me something that I owned, that I bought. All of a sudden, years later, it's illegal and they decide to ban it,” Cargill said . “They can’t do that.”

Gun control advocates, however, criticized the decision.

“This decision by the high court is dangerous and wrong. The ATF must not be deterred and continue to aggressively enforce the nation's gun laws,” said Eric Tirschwell, executive director of Everytown Law, in a press release.

President Joe Biden, following the decision, issued a statement calling on Congress to ban bump stocks as well as assault weapons.

But given the narrow partisan divides on Capitol Hill, the influence of the gun lobby and the politics of the campaign trail, immediate legislative action in response to the court's ruling is unlikely, even if a ban has enjoyed some bipartisan support in 2017.

Trump's campaign said the court's ruling “should be respected” and that “the right to keep and bear arms has never been more critical.” The statement, however, does not address the fact that the ATF imposed the ban under his administration.

ABC News' Alexandra Hutzler contributed to this report.