The Supreme Court on Friday struck down a ban on stockings like those used in the nation's deadliest mass shooting, when 60 people were killed and 500 injured at an outdoor concert in Las Vegas in 2017.
In a 6-3 decision, the justices rejected opinions from the Biden and Trump administrations, ruling that bump weapons could not be banned like illegal machine guns because the trigger action operates in a different way.
The six conservatives on the court were in the majority and the three liberals dissented.
After the Las Vegas shooting, President Trump ordered federal regulators to reclassify bump weapons as illegal machine guns because they allow a shooter to fire hundreds of rounds per minute. Biden administration lawyers defended that rule.
But the court's conservatives said the action of a stock differs slightly from that of a machine gun and therefore cannot be banned without an additional change in the law.
Congress first restricted machine guns in 1934 in response to mob killings during Prohibition, including the St. Valentine's Day massacre in Chicago. Since then, Congress has reviewed and updated the ban several times.
The case decided Friday did not involve the Second Amendment or the right to bear arms. Instead, he focused on how machine guns were described when Congress banned their sale. They were defined as weapons that fired automatically by simply pulling the trigger.
The Las Vegas shooter had an arsenal of assault rifles in his hotel room overlooking the concert venue. Authorities later said that 14 guns were equipped with stocks that had allowed the gunman to fire more than 1,000 rounds in 11 minutes.
More than 500,000 stocks were said to be in private hands when the Bureau of Alcohol, Tobacco and Firearms issued its ban in 2018. Owners were told they must hand over those guns.
Michael Cargill, a Texas gun store owner, turned in his two stocks and later filed a lawsuit challenging the law. He won before the conservative Fifth Circuit Court in New Orleans, which found the wording of the law ambiguous.
U.S. Attorney General Elizabeth Prelogar appealed and urged the justices to reinstate the ban.
