## Facts

- The National Firearms Act defines “machinegun” to include a weapon that “shoots … automatically more than one shot, without manual reloading, by a single function of the trigger,” and also includes certain parts intended to convert a weapon into a machinegun. 26 U.S.C. § 5845(b).
- A semiautomatic firearm fires one shot per trigger operation; the trigger must reset before the next shot can fire.
- “Bump firing” is a technique that uses recoil to help the shooter rapidly reengage the trigger; a bump stock is an accessory that facilitates this rapid trigger reengagement but does not change the firearm’s basic semiautomatic firing mechanism.
- For years, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) consistently stated that semiautomatic firearms equipped with bump stocks were not “machineguns” under § 5845(b).
- After the October 2017 Las Vegas mass shooting, where a shooter used semiautomatic rifles with bump stocks to fire hundreds of rounds at high speed, ATF changed course.
- In 2018, ATF issued a final rule amending its regulations to classify bump-stock-type devices as “machineguns,” making continued possession unlawful and requiring owners to destroy the devices or surrender them to ATF within 90 days.
- Michael Cargill, a Texas gun-store owner, surrendered two bump stocks under protest and sued the Attorney General, ATF, and related federal parties under the Administrative Procedure Act (APA), arguing ATF lacked statutory authority because bump stocks do not satisfy § 5845(b).
- The federal district court upheld the rule and entered judgment for the government.
- A Fifth Circuit panel affirmed, but the Fifth Circuit sitting en banc reversed, concluding the statute did not reach bump stocks and, in any event, any ambiguity had to be resolved in favor of the citizen under the rule of lenity.
- The Supreme Court granted certiorari to decide whether bump stocks fall within § 5845(b)’s definition of “machinegun,” and thus whether ATF’s 2018 rule was authorized.

## Issues

1. Is a semiautomatic rifle equipped with a bump stock a “machinegun” under 26 U.S.C. § 5845(b) because it shoots “automatically more than one shot … by a single function of the trigger”?
2. If not, did ATF exceed its statutory authority under the APA by issuing the 2018 rule classifying bump-stock-type devices as “machineguns”?

## Decision

- The Supreme Court affirmed the en banc Fifth Circuit, 6–3 (Justice Thomas for the Court).
- The Court held that a bump stock does not convert a semiautomatic rifle into a “machinegun” under § 5845(b), so ATF’s 2018 bump-stock rule exceeded the authority Congress gave the agency.
- On “single function of the trigger,” the Court read the phrase to refer to the trigger’s mechanical operation. With or without a bump stock, a semiautomatic rifle fires only one round per trigger operation because the trigger must reset between shots; bump stocks only allow those separate trigger operations to occur more quickly.
- On “automatically,” the Court read the statute to require more than rapid fire; the weapon must fire more than one shot through a self-acting mechanism after a single trigger function. Bump-stock firing still depends on the shooter’s ongoing input (including maintaining pressure and allowing recoil-driven movement) and still involves repeated trigger operations.
- The Court rejected the government’s reliance on § 5845(b)’s “part” language (covering parts intended for converting a weapon into a machinegun) because a bump stock does not convert the weapon into a statutory machinegun as defined by the “single function of the trigger” requirement.
- Justice Alito concurred, agreeing that the statute as written does not cover bump stocks and stating that any broader prohibition should come from Congress.
- Justice Sotomayor dissented (joined by Justices Kagan and Jackson), reasoning that bump stocks enable continuous, high-rate fire through a single sustained shooter action and should be treated as machineguns under § 5845(b).

## Legal Principles

- Statutory definitions that carry criminal consequences are applied according to their best reading; agencies may not expand criminal liability by regulation beyond what Congress enacted.
- Under § 5845(b), “single function of the trigger” refers to a single mechanical trigger operation; a semiautomatic firearm that requires reset between shots does not satisfy that element merely because an accessory enables rapid successive trigger operations.
- “Automatically” in § 5845(b) requires that more than one shot occurs through the weapon’s self-acting mechanism after a single trigger function, not simply that the weapon can be fired very rapidly with continued shooter input.
- The “conversion part” clause in § 5845(b) covers parts that, when installed, convert a weapon into one that meets the statutory definition; a part does not qualify if the resulting firearm still fires only one shot per trigger operation.
- Under the APA, a court must set aside agency action “in excess of statutory jurisdiction, authority, or limitations”; where a criminal statute is involved, interpretive doubt is not resolved by agency rulemaking, and lenity principles favor the narrower construction.

## Conclusion

Garland v. Cargill held that bump stocks do not make a semiautomatic rifle a “machinegun” under 26 U.S.C. § 5845(b) because the firearm still fires only one shot per mechanical trigger operation and does not fire more than one shot automatically by a single trigger function; therefore, ATF lacked statutory authority to issue its 2018 rule classifying bump-stock-type devices as machineguns.


Garland v. Cargill, 602 U.S. 406, 144 S. Ct. 1613 (2024)