Does the undefined term 'controlled substance' in the federal Sentencing Guidelines refer to substances controlled by federal law or state law?

QUESTIONS PRESENTED United States Sentencing Guidelines enhance the sentence for drug offenders and gun offenders, if, among other things, they have prior “felony convictions of either a crime of violence or a controlled substance offense.” U.S.S.G. § 4B1.1; U.S.S.G. § 2K2.1(a). The Guidelines define “controlled substance offense” as, in part, “an offense under federal or state law, punishable by imprisonment for a term exceeding one year, that prohibits the manufacture, import, export, distribution, or dispensing of a controlled substance... .” U.S.S.G. § 4B1.2(b) (Emphasis added). The Guidelines do not define the term “controlled substance,” and the circuits are openly split on how to do so. The questions presented are: 1. Does the undefined term “controlled substance” in the federal Sentencing Guidelines mean substances that are controlled by federal law (in the form of the federal Controlled Substances Act (CSA)), or does the term also refer to the myriad definitions found in each state law, such that prior convictions from states with drug schedules broader than the federal CSA qualify as predicate “controlled substance offenses” under the Guidelines? The same question is currently pending before this Court in Atwood v. United States, No. 20-8213. 2. When defining an operative, but undefined, term in the Federal Sentencing Guidelines, should courts use analogous federal statutory definitions, state statutory definitions, or judge-made definitions for that term? ii 3. Can a district court impose Guidelines enhancements for “controlled substances” without setting forth a categorical test to differentiate “controlled substances” from non-“controlled substances”? ili