SALT LAKE CITY — A Utah gun rights advocate is suing the federal government over a newly imposed ban on an accessory that modifies rifles to fire like automatic weapons.

Clark Aposhian, chairman of the Utah Shooting Sports Council, argues in the lawsuit that the Department of Justice and Bureau of Alcohol, Tobacco, Firearms and Explosives violated the Constitution in prohibiting a device known as a bump stock.

"This is obviously about bump stocks but I think it speaks to something much bigger," he said. "This is about government overreach. This is about administration overreach."

Bump stocks came under intense scrutiny after a gunman used them to kill 58 people at a country music concert in Las Vegas in 2017.

Several bills in Congress to outlaw them didn't go anywhere. Some members of Utah's then all-Republican congressional delegation were open to banning them. New Sen. Mitt Romney, R-Utah, has said the devices should be regulated and not generally available.

But the Trump administration in late December adopted a new federal rule that redefined the devices as "machine guns," therefore banning them under existing law. The rule takes effect March 26.

After the Department of Justice announced the rule, the New Civil Liberties Alliance, an organization based in Washington, D.C., that aims to protect constitutional liberties from the "administrative state," approached Aposhian to be the plaintiff in the case filed in U.S. District Court in Salt Lake City. Aposhian owns a Slide Fire bump stock.

The organization is seeking a temporary injunction to stop the rule from taking effect while the case is argued.

The civil rights alliance is not a gun rights group and has no position on the propriety of a bump stock ban, but argues only Congress — not the executive branch — has the power to make laws, and in this case federal lawmakers did not take action, said Caleb Kruckenberg, the lead attorney in the case.

"Either Congress was unable or unwilling to make a legislative choice on this issue. Our prime contention is that's not a reason for the executive branch to go in and rewrite the law," he said.

Aposhian contends the Trump administration is illegally changing the rules in the middle of the game, and "paying lip service to the Second Amendment in this case, but it could be the First Amendment next time."

"Besides firearms, what is safe?" he said. "What is not subject to the whim of an administration?"

Should a judge not block the law, Aposhian said he intends to comply "in any of the prescribed ways," which includes destroying his bump stock or turning it over to the ATF.

"I am not going to draw the line in the sand and die standing on top of my bump stock, and nor should we have to," he said.

Americans own an estimated 520,000 bump stocks, according to the ATF. Sales of the devices soared after the Las Vegas shooting as talk of a government ban picked up.