Bump stocks allow shooters to fire semi-automatic firearms rapidly by maintaining forward pressure on the rifle, thus pushing the trigger against a stationary finger. Recoil energy from the subsequent discharge propels the gun backward, resetting the trigger, which is engaged immediately again and again in the same manner as long as the shooter maintains forward pressure on the rifle.
Relatively few Americans were aware of bump stocks until October 1, 2017, when a shooter used them to open fire on a crowd of concertgoers on the Las Vegas strip. In just ten minutes, the shooter fired over 1,000 shots, killing 60 people and wounding at least 413. In the wake of the tragedy, public pressure to ban bump stocks mounted. Multiple bills to this effect were introduced in Congress. Before lawmakers could act on any of them, however, the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) promulgated a final rule purporting to ban possession and transfer of bump-stock-equipped semi-automatic rifles because they qualify as “machinegun[s]” under the Gun Control Act and National Firearms Act.
After purchasing bump stocks and turning them over to ATF as the final rule required, Michael Cargill brought suit to challenge ATF’s final rule. A federal district court concluded that ATF had the better reading of the statutory definition. A Fifth Circuit panel affirmed, noting that three other circuits had already rejected similar challenges to the ATF final rule.
The Fifth Circuit granted rehearing en banc and held 13-3 that ATF’s final rule violated the APA. See Cargill v. Garland, No. 20-51016, 2023 WL 119435 (5th Cir. Jan. 6, 2023) (en banc). The majority agreed that the unambiguous language of the statute compelled that result. It also concluded that the rule of lenity compelled the same result. In the Fifth Circuit, each of these alternative holdings is binding precedent, not obiter dictum.
Congress defined “machinegun” to mean “any weapon which shoots automatically more than one shot by a single function of the trigger,” or any accessory that allows a firearm to shoot in that manner. See 26 U.S.C. § 5845(b). The majority opinion, authored by Judge Elrod, held that the language of that definition unambiguously foreclosed ATF’s attempt to treat bump stocks as “machinegun[s]” in two ways. First, because a bump-stock-equipped semi-automatic rifle fires only one shot each time the trigger is engaged, the court concluded that it does not fire more than one shot “by a single function of the trigger.”
The government argued that the court should interpret the statute from the perspective of the shooter such that “by a single function of the trigger” means that “the shooter acts once on the trigger” rather than “the trigger acts once.” Rejecting that view, the majority noted that the definition focuses only on the trigger, making no mention of the shooter.
Second, the majority held that a bump-stock-equipped semi-automatic rifle does not fire “automatically,” a concept that the court interpreted to mean “self-acting.” The majority emphasized that “automatically” in the statutory definition is modified—and thus limited—by the clause “by a single function of the trigger.” Because a shooter cannot bump fire simply by pulling the trigger a single time, the majority reasoned, bump-stock-equipped semi-automatic rifles do not shoot “automatically” in the relevant sense.
Having held that the plain language of the statute unambiguously foreclosed ATF’s interpretation in the two ways just discussed, the majority proceeded to explain its third holding: that even if the statute were ambiguous, the rule of lenity would require it to rule in Cargill’s favor. The majority acknowledged that courts have considered two standards when assessing how much ambiguity is required before lenity kicks in. Some apply a “reasonable doubt” standard, while others require “grievous ambiguity.” The majority, however, left that debate unresolved because if the statutory definition of “machinegun” were ambiguous, lenity would apply under either standard.
That was so, the majority explained, because the court had already exhausted all traditional tools of statutory construction. Where ambiguity remains even after the court has emptied the judicial toolkit in this way, the ambiguity is terminal even under the more demanding “grievous ambiguity” test.
In 2020, the Supreme Court declined to review the D.C. Circuit’s decision upholding ATF’s final rule. Now that the Fifth Circuit’s en banc opinion in Cargill has split with the three other circuits to address the issue, the justices may be more inclined to weigh in.
