By Lawrence Hurley

WASHINGTON (Reuters) – The U.S. Supreme Court on Thursday rejected a request by gun rights activists to put on hold the Trump administration’s ban on “bump stock” attachments that allow semi-automatic weapons to be fired rapidly, a rare recent instance of gun control at the federal level.

The court in a brief order refused to grant a temporary stay sought by plaintiffs including the group Gun Owners of America in a lawsuit filed in Michigan challenging the ban while litigation continues.

The policy took effect on Tuesday on the same day that Chief Justice John Roberts rejected a similar bid to delay implementation in a separate legal challenge brought in Washington by individual gun owners and gun rights groups including the Firearms Policy Foundation and Florida Carry Inc.

An appeals court previously exempted specific people and groups involved in the Washington case from the ban while that litigation proceeds.

President Donald Trump pledged to ban the devices soon after a gunman used them in an October 2017 shooting spree that killed 58 people at a country music festival in Las Vegas. The Justice Department on Dec. 18 announced plans to implement the policy.

Bump stocks use a gun’s recoil to bump its trigger, enabling a semiautomatic weapon to fire hundreds of rounds per minute, which can transform it into a machine gun. The Justice Department’s regulation followed the lead of many states and retailers that imposed stricter limits on sales of guns and accessories after a deadly shooting at a Florida high school in February 2018.

In the Michigan case, a federal judge already has ruled in favor of the administration. The Cincinnati, Ohio-based 6th U.S. Circuit Court of Appeals refused to put the ban on hold pending appeal. Other plaintiffs in that case include the Gun Owners Foundation, the Virginia Citizens Defense League and three individual gun owners.

In the Washington case, a federal judge also upheld the ban, prompting gun rights advocates to appeal to the U.S. Court of Appeals for the District of Columbia Circuit. That court has heard oral arguments but has not yet ruled.

Those challenging the policy have argued that the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) lacks the authority to equate bump stocks with machine guns. One of the laws at the center of the legal dispute was written more than 80 years ago, when Congress restricted access to machine guns during the heyday of American gangsters’ use of “tommy guns.”

Trump’s fellow Republicans typically oppose gun control measures and are protective of the right to bear arms promised in the U.S. Constitution’s Second Amendment. In 2017, there were 39,773 gun deaths in the United States, according to the most recent U.S. Centers for Disease Control and Prevention figures released in December.

The FBI said in January it had found no clear motive for the 64-year-old Las Vegas gunman, Stephen Paddock, in the deadliest mass shooting in modern U.S. history.

(Reporting by Lawrence Hurley; Editing by Will Dunham)