The US Court of Appeals for the Fifth Circuit Friday struck down a Trump-era ban on rapid-fire bump stocks. The ban prevented anyone from possessing bump stock devices, which enable a shooter to rapidly fire multiple rounds from semi-automatic weapons after an initial trigger pull, and encourages possessors to either destroy or turn in their devices.

The issue involves a conflict in the interpretation of federal statutes. Gun rights advocates argue that bump stocks do not come under the definition of illegal machine guns in federal law. Contrarily, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) says they do, a position endorsed by the Biden administration.

Judge Jennifer Walker Elrod delivered the majority opinion, saying:

A plain reading of the statutory language, paired with close consideration of the mechanics of a semi-automatic firearm, reveals that a bump stock is excluded from the technical definition of ‘machinegun’ set forth in the Gun Control Act and National Firearms Act. But even if that conclusion were incorrect, the rule of lenity would still require us to interpret the statute against imposing criminal liability.

Judge Stephen Higginson dissented and argued that “under the majority’s rule, the defendant wins by default whenever the government fails to prove that a statute unambiguously criminalizes the defendant’s conduct.”

The Trump administration promulgated the ban in March 2019 after a gunman killed 58 people in Las Vegas in 2017. The US Supreme Court declined to hear a challenge to the ban in November 2022.