Come Tuesday, bump stock owners across the country will have to give up their firearm accessory or face the possibility of jail time and fines.

All of them, that is, except for at least one: noted Utah gun rights advocate and Utah Shooting Sports Council chairman Clark Aposhian.

A federal judge recently denied Aposhian’s attempt for an injunction that would allow him to keep his bump stock — a firearm attachment that modifies semi-automatic weapons to fire like a machine gun — until his lawsuit against Department of Justice and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) was settled.

The lawsuit, filed in January, argues that banning the bump stock, which was used in the 2017 Las Vegas massacre, is unconstitutional because it amounts to the executive branch rewriting laws, which the lawsuit sates is the job of Congress.

Aposhian’s attorneys appealed U.S. District Judge Jill Parrish’s March 8 decision to the 10th Circuit Court of Appeals, and Thursday that court issued a temporary stay, meaning Aposhian will get to keep his bump stock until his lawsuit is resolved.

“Today the Court of Appeals told the ATF that it could not rush through the bump stock ban without meaningful judicial review. The Court understands the stakes and is refusing to let an innocent owner be declared a felon, as scheduled,” said Caleb Kruckenberg, litigation counsel for the New Civil Liberties Alliance, a nonprofit civil rights organization that is representing Aposhian in his case.

Parrish denied Aposhian’s request for an injunction because he said the Utahn’s lawsuit didn’t show “a substantial likelihood of success.”

President Donald Trump promised in March 2018 that he would ban bump stocks because they “turn legal weapons into illegal machines.” To do so, his administration reclassified them in December as machine guns; federal law heavily restricts buying, selling or owning those weapons.

Congress hasn’t made any laws that prohibit the possession of bump stocks, though it has considered several bills in recent years that would have regulated the devices, the lawsuit states.

The ban reverses a 2010 ATF decision, and a second one under then-President Barack Obama, that found bump stocks were not the same as machine guns and couldn’t be regulated as if they were.

The new interpretation came after intense scrutiny on bump stocks after the attachments were used in an October 2017 shooting at a country music concert in Las Vegas — the worst mass shooting in modern American history, which left 58 dead and almost 100 injured.