Cargill v. United States

Michael Cargill, a gun rights advocate, challenged the federal rule issued by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) that reclassified bump stocks as "machineguns" under the National Firearms Act. The case reached the U.S. Supreme Court in 2025, where Cargill argued that the ATF exceeded its statutory authority by unilaterally expanding the definition of a machinegun without congressional approval. The government defended the ban as a necessary public safety measure following the 2017 Las Vegas mass shooting. The Court examined the plain text of the statute, which defines a machinegun as a weapon that fires automatically by a single function of the trigger, and considered whether a bump stock meets that definition.

The Supreme Court ruled 6-3 in favor of Cargill, holding that the ATF's bump stock ban was unlawful. The majority opinion stated that a bump stock does not enable a firearm to fire automatically by a single function of the trigger, and therefore does not satisfy the statutory definition of a machinegun. The rule was vacated.

Whether the ATF's interpretation that bump stocks fall within the statutory definition of "machinegun" is entitled to deference, or whether the agency exceeded its authority by effectively creating criminal law without clear congressional authorization.

The decision reignited intense national debate over gun control, with advocates calling for legislative action to explicitly ban bump stocks. It underscored judicial skepticism toward expansive agency rulemaking and reinforced the principle that major criminal prohibitions require clear statutory mandates from Congress. The ruling prompted several states to enact their own bump stock bans.