UPDATE 1-U.S. Supreme Court refuses to block Trump's gun 'bump stock' ban

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 in Washington brought 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 case continues.

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. (Reporting by Lawrence Hurley; Editing by Will Dunham)