Pundits have tried to read the tea leaves following the argument in the Supreme Court in Garland v. VanDerStok on October 8. In its Final Rule, ATF expanded the definition of "firearm" beyond what Congress provided in the Gun Control Act (GCA), and it expanded the definition of "frame or receiver" beyond the agency's own definition that was on the books since 1968. In the argument, serious questions were raised about the extent to which an agency may revise a criminal statute.
That concern was expressed right at the beginning when Justice Thomas asked Solicitor General Prelogar whether the regulation "cover[s] all of Chapter 44," which is the GCA portion of 18 U.S.C. (the federal criminal code), and whether it "appl[ies] under 924," which is the GCA section that provides criminal penalties. Prelogar's response was "yes" to both. So whether a person is committing a felony depends on whether the more narrow definition of "firearm" enacted by Congress, or the broader definition adopted by ATF, applies.
Justice Kavanaugh probed in detail into the implications of the agency's expansion of the reach of the criminal law. Expressing concern about mens rea, he noted that "this is an agency regulation that broadens a criminal statute beyond what it had been before." "So what about the seller," he asked "who is truly not aware … that they are violating the law and gets criminally charged?"
