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

QUESTION PRESENTED Does the undefined term “controlled substance” in the federal Sentencing Guidelines mean substances controlled by federal law, 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” for purposes of the career-offender enhancement? The same question is currently pending before this Court in Ward v. United States, No. 20-7327. i