Bump stocks and machine guns: 5th Circuit is fourth appellate court to hear case on ATF rule

This week, the 5th Circuit Court of Appeals became the fourth appellate court to hear a case involving the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) rule banning bump stocks on firearms that was promulgated under the Trump administration.

Then-President Trump started the process that led to the ATF's rule, which makes bump stocks equivalent to illegal machine guns in terms of federal law. The regulatory action followed the October 2017 Las Vegas concert massacre, where the shooter used a rifle equipped with a bump stock to fire into the crowd, killing 58 and injuring over 400.
Over 500,000 bump stocks were legally owned by Americans before the ban went into effect, after which owners had to turn them into the ATF or destroy them without receiving compensation, lest they risk up to 10 years in prison and a $250,000 fine, according to the New Civil Liberties Alliance (NCLA).

In the case before the 5th Circuit, Michael Cargill v. Garland, et al., the plaintiff is a U.S. Army veteran and gun shop owner in Austin, Texas. When the bump stock rule went into effect, he turned in his bump stocks to the ATF to follow the law, and then sued the government over the new interpretation of the rule. 

The case has hinged on whether the ATF improperly issued a "legislative rule," thereby usurping the sole legislative authority of Congress under the Constitution.