WASHINGTON — The Supreme Court agreed on Friday to decide whether a Trump era-ban on bump stocks, the gun attachments that allow semi-automatic weapons to fire rapidly like machine guns, violates federal law.

The justices will hear arguments early next year over a regulation put in place by the Justice Department after a mass shooting in Las Vegas in 2017.

Federal appeals courts have come to different decisions about whether the regulation defining a bump stock as a machine gun comports with federal law.

The justices said they will review the Biden administration’s appeal of a ruling by the 5th U.S. Circuit Court of Appeals in New Orleans that invalidated the ban.

Previous Gun Laws

The Supreme Court already is weighing a challenge to another federal law that seeks to keep guns away from people under domestic violence restraining orders, a case that stems from the landmark decision in 2022 in which the six-justice conservative majority expanded gun rights.

The new case is not about the Second Amendment right to “keep and bear arms,” but rather whether the Trump administration followed federal law in changing the bump stock regulation.

The Ban on Bump Stocks

The ban on bump stocks took effect in 2019. It stemmed from the Las Vegas shooting in which the gunman, a 64-year-old retired postal service worker and high-stakes gambler, used assault-style rifles to fire more than 1,000 rounds in 11 minutes into a crowd of 22,000 music fans.

Most of the rifles were fitted with bump stock devices and high-capacity magazines. A total of 58 people were killed in the shooting, and two died later. Hundreds were injured.

Change in Federal Bureau’s Stance

The Trump administration’s ban on bump stocks was an about-face for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives. In 2010, under the Obama administration, the agency found that a bump stock should not be classified as a machine gun and therefore should not be banned under federal law.

Following the Las Vegas shooting, officials revisited that determination and found it incorrect.

What Are Bump Stocks?

Bump stocks harness the recoil energy of a semi-automatic firearm so that a trigger “resets and continues firing without additional physical manipulation of the trigger by the shooter,” according to the ATF.

A shooter must maintain constant forward pressure on the weapon with the non-shooting hand and constant pressure on the trigger with the trigger finger, according to court records.

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Legal Decisions

The full U.S. 5th Circuit ruled 13-3 in January that Congress would have to change federal law to ban bump stocks.

“The definition of ‘machinegun’ as set forth in the National Firearms Act and Gun Control Act does not apply to bump stocks,” Judge Jennifer Walker Elrod wrote for the 5th Circuit.

But a panel of three judges on the federal appeals court in Washington looked at the same language and came to a different conclusion.

Judge Robert Wilkins wrote for the U.S. Court of Appeals for the District of Columbia Circuit that “under the best interpretation of the statute, a bump stock is a self-regulating mechanism that allows a shooter to shoot more than one shot through a single pull of the trigger. As such, it is a machine gun under the National Firearms Act and Gun Control Act.”

A decision is expected by early summer in Garland v. Cargill, 22-976.