The Supreme Court is hearing a challenge to a Trump-era ban on a gun accessory known as bump stocks

WASHINGTON — The Supreme Court on Wednesday will invoke a Trump-era ban on bump stocks, a weapon accessory used in a Las Vegas massacre that was the deadliest mass shooting in modern U.S. history.

A gun shop owner in Texas claims the Trump administration failed to follow federal law when it reversed course and banned bump stocks, which allow semi-automatic weapons to fire rapidly like machine guns.

The Biden administration is defending the ban, saying regulators were right to review previous findings and ban bump stocks under laws against machine guns that are decades old.

Federal appeals courts are divided over the bump stock rule, which marks the latest gun case to reach the Supreme Court. The case offers a conservative supermajority court a new test for determining the limits of gun restrictions in an era plagued by mass shootings.

The justices are considering a new case challenging a federal law aimed at keeping guns away from people under domestic violence restraint orders, stemming from a landmark 2022 decision in which the six-justice conservative majority expanded gun rights.

However, the bump stock case is not directly about Second Amendment gun rights. Instead, plaintiffs argue that the Bureau of Alcohol, Tobacco, Firearms and Explosives exceeded its authority in imposing the ban.

“If Congress had passed this law, the NCLA would not be filing this lawsuit,” said Mark Chenoweth, president of the New Civil Liberties Alliance. His group represents Michael Cargill, a Texas gun shop owner and Army veteran. He bought two bump stocks in 2018 during the rulemaking process, then transferred them and filed a lawsuit after the rule became final the following year, court documents show.

The ban was a change for the ATF, which had previously decided that bump stocks should not be classified as machine guns and therefore would not be banned under federal law.

That changed, however, after a gunman in Las Vegas attacked a country music festival in 2017 with assault-style rifles, many of which were equipped with bump stocks and high-capacity magazines. In eleven minutes, more than a thousand bullets were fired into the crowd, killing sixty people and wounding hundreds of others.

Marisa Marano, 42, survived the shooting at the show she attended with her sister, but continues to struggle with the massacre’s lasting effects on her life and community. “I will never forget the sound of a machine gun firing into the crowd that night as Gina and I ran for our lives,” said Marano, who now volunteers for the group Moms Demand Action and hopes the Supreme Court upholds the ban.

“The bump stock rule is simply common sense,” said Billy Clark, an attorney with the gun safety group Giffords.

Bump stocks are accessories that replace the butt of a rifle, the part that rests against the shoulder. They harness the recoil energy of the weapon so that the trigger bounces against the shooter’s stationary finger, allowing the weapon to fire rapidly.

Invented in the early 2000s, they were one of a growing number of devices that came to market following the passage of the 1994 measure known as the federal assault weapons ban, and were designed to “reproduce automatic fire… without converting these guns. in ‘machine guns,’” ​​the Justice Department wrote in court documents.

Between 2008 and 2017, the ATF decided that while bump stocks made a weapon fire faster, it did not turn them into machine guns. The agency revisited the issue at the urging of then-President Donald Trump after the Las Vegas shooting and decided that the rapid-fire weapons they enabled made them illegal machine guns.

Prosecutors argue that rifles with bump stocks are different from machine guns because the shooter still has to apply pressure to the weapon to keep the rapid fire going and the trigger continues to move, so the accessories are not subject to machine gun laws.

The government, on the other hand, pointed out that traditional machine guns also require pressure from the shooter. The Justice Department also states that because the shooter’s finger remains still while the weapon fires hundreds of rounds per minute, weapons with bump stocks fall under the legal definition of machine guns.

There were about 520,000 bump stocks in circulation when the ban took effect in 2019, forcing people to surrender or destroy them, with a combined estimated loss of $100 million, plaintiffs said in court documents.

Federal appeals courts have reached differing decisions on whether the regulation defining a bump stock as a machine gun is constitutional.

A three-judge panel of the federal appeals court in Washington DC upheld the ban, ruling that “a bump stock is a self-regulating mechanism that allows a shooter to fire more than one shot with a single pull of the trigger.”

But the New Orleans-based 5th Circuit Court of Appeals invalidated the ban, ruling that the definition of machine guns under the National Firearms Act and Gun Control Act does not apply to bump stocks.

The Supreme Court appealed the 5th Circuit’s decision.

The case also comes at a time when the 6-3 conservative majority is increasingly skeptical of the powers of federal agencies. This term, the justices are also weighing the challenges against aspects of the Consumer Financial Protection Bureau and the Securities and Exchange Commission.

A decision is expected early summer.