Syllabus

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is being done in connection with this case, at the time the opinion is issued. The syllabus constitutes no part of the opinion of the Court but has been prepared by the Reporter of Decisions for the convenience of the reader. See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.

SUPREME COURT OF THE UNITED STATES

Syllabus

BONDI, ATTORNEY GENERAL, ET AL. v. VANDERSTOK ET AL. CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FIFTH CIRCUIT

No. 23–852. Argued October 8, 2024—Decided March 26, 2025 The Gun Control Act of 1968 (GCA) requires those engaged in importing, manufacturing, or dealing in firearms to obtain federal licenses, keep sales records, conduct background checks, and mark their products with serial numbers. The Act defines “firearm” to include “(A) any weapon . . . which will or is designed to or may readily be converted to expel a projectile by the action of an explosive; [and] (B) the frame or receiver of any such weapon.” 18 U. S. C. §921(a)(3). Recent years have witnessed profound changes in how guns are made and sold, with companies now able to sell weapon parts kits that individuals can as- semble into functional firearms at home. These kits vary widely in how complete they come and in how much work is required to finish them. Sales have grown exponentially, with law enforcement agencies reporting a dramatic increase in untraceable “ghost guns” used in crimes—from 1,600 in 2017 to more than 19,000 in 2021. In 2022, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) adopted a rule interpreting the Act to cover weapon parts kits that are “designed to or may readily be converted to expel a projectile,” 27 CFR §478.11, and “partially complete, disassembled, or nonfunc- tional” frames or receivers, §478.12(c). Before ATF could enforce its rule, gun manufacturers and others filed what they described as a fa- cial challenge under the Administrative Procedure Act, arguing that the GCA cannot be read to reach weapon parts kits or unfinished frames or receivers. The District Court agreed and vacated the rule. The Fifth Circuit affirmed, holding that §921(a)(3)(A) categorically does not reach weapon parts kits regardless of completeness or ease of assembly, and that §921(a)(3)(B) reaches only finished frames and re- ceivers. 2 BONDI v. VANDERSTOK

Syllabus Held: The ATF’s rule is not facially inconsistent with the GCA. Pp. 7– 24. (a) Section 478.11’s provisions addressing weapon parts kits are not facially invalid under §921(a)(3)(A). That subsection contains two re- quirements: a “weapon” must be present, and that weapon must be able to expel a projectile by the action of an explosive, designed to do so, or susceptible of ready conversion to operate that way. Some weapon parts kits meet that description. Consider, for instance, Poly- mer80’s “Buy Build Shoot” kit, which contains all necessary compo- nents to build a semiautomatic pistol and can be assembled in about 20 minutes using common tools. That kit qualifies as a “weapon” be- cause: (1) artifact nouns like “weapon” often describe unfinished ob- jects when their intended function is clear, as with a disassembled ri- fle; (2) the statute treats starter guns as weapons though they require conversion work; and (3) the statutory text contemplates that some things short of fully operable firearms qualify as “weapons.” The kit also satisfies the statute’s second requirement, as it requires no more time, expertise, or specialized tools to complete than a starter gun, which the statute treats as readily convertible into a functioning fire- arm. While other kits