Congress enacted the Gun Control Act of 1968 (GCA) to keep guns out of the hands of criminals and others who should not have them and help law enforcement investigate serious gun crimes. Among other things, the law requires those who manufacture and deal in “firearms” to procure a federal firearms license, maintain records of the acquisition and transfer of firearms, conduct background checks, and mark every firearm with a serial number. The term “firearm” is defined to include “any weapon (including a starter gun) which will or is designed to or may readily be converted to expel a projectile by the action of an explosive” or “the frame or receiver of any such weapon.”

In 2022, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) promulgated a rule clarifying that the definition of “firearm” includes certain weapon parts kits that may be readily converted into firearms, as well as certain partially complete, disassembled, or nonfunctional frames or receivers.” A group of gun manufacturers and enthusiasts filed suit challenging the rule as contrary to the GCA, and a federal district court and the Fifth Circuit Court of Appeals ruled in their favor. The United States asked the Supreme Court to stay the district court’s vacatur of ATF’s rule and hear the case on the merits, and the Court agreed to do so.

CAC filed an amicus brief in the Supreme Court in support of the United States. Our brief makes two main points.

First, our brief describes how ATF’s rule is consistent with the plain text of the GCA. It explains that the ordinary meaning of the GCA’s phrase “may be readily converted” indisputably covers the kits and devices specified in ATF’s rule, which “may be readily converted” into fully functional firearms. Dictionaries from the 1960s defined “readily” to mean “with fairly quick efficiency.” And they defined “convert” chiefly as “to change or turn from one state to another” or to “transform” or “transmute.” Under these definitions, when an amateur working at home transforms a weapons parts kit from an unfinished, disassembled state into a finished state with fairly quick efficiency, that person “readily . . . convert[s]” the kit into a weapon that “expel[s] a projectile by the action of an explosive” within the meaning of the GCA.

Our brief also explains that dictionaries from the 1960s consistently defined the terms “frame” and “receiver” broadly enough to cover partially complete or nonfunctional frames and receivers. Those dictionaries focused on the purpose that the “frame” or “receiver” serves and the manner in which it is used: as the basic skeleton of a firearm to which other parts are attached to create a functional machine. They say nothing about the “completeness” of a “frame” or “receiver” or require it to be ready-to-use, and they plainly would have encompassed a frame or receiver that was missing just a few drill holes, or that required the removal of just a few plastic tabs, or that could be readily assembled from a kit containing all the key parts.

Second, our brief demonstrates that history of the GCA confirms what its text makes clear: the Act applies to weapon parts kits and incomplete frames and receivers. The GCA was passed to address the growing problem of unregulated access to mail-order guns. After the assassinations of President John F. Kennedy, the Reverend Dr. Martin Luther King, Jr., and Senator Robert F. Kennedy, Congress called for an end to the “no questions asked” approach that allowed disqualified purchasers to obtain firearms anonymously. Congress updated the definition of “firearm” to close what President Lyndon B. Johnson called “the brutal loopholes in our laws.” And when Congress included “starter guns” in its definition of “firearm,” it was broadly referring to devices or sets of parts which could readily be converted into a firearm, regardless of the precise method of conversion.

The 1968 update to the definition of “firearm” was thus part of a larger scheme designed to crack down on gun manufacturers who sought to cash in on the benefits of selling firearms while evading regulation. Congress saw through that scheme in 1968, and the Supreme Court should see through it today.