WASHINGTON – The U.S. Supreme Court refused to halt a new federal ban on ownership of bump stocks, the attachments that can make a semi-automatic rifle fire like a machine gun.

The justices turned away a request, filed by people and groups challenging the ban in a Michigan lawsuit, to block the policy while the litigation goes forward. The ban, which imposes criminal penalties, went into effect Tuesday.

The court made no comment and no justice publicly dissented. Chief Justice John Roberts previously rejected a similar request in a separate lawsuit.

The lawsuits contend that the Bureau of Alcohol, Tobacco, Firearms and Explosives improperly expanded the government’s long-standing definition of machine guns to include bump stocks. Machine guns have been heavily regulated in the U.S. since 1934 and virtually banned since 1986.

The Trump administration urged the court to leave the ban in force, saying bump stocks qualified as a machine gun under the National Firearms Act.

Bump stocks, previously an obscure gun accessory, became infamous after they were linked to the Las Vegas concert massacre on Oct. 1, 2017. The gunman owned multiple such devices, law enforcement authorities said. Fifty-eight people were killed in the attack, the deadliest mass shooting in modern American history.

Trump then ordered the Justice Department to draft regulations banning use of the accessories.

Gun rights advocates say U.S. residents possess 500,000 bump stocks, valued at more than $100 million.