Whether the term 'controlled substance' in the Sentencing Guidelines refers only to substances controlled under federal law or also includes substances controlled under state law

Under the federal Sentencing Guidelines § 2K2.1(a)( 2), a defendant previously convicted of a “controlled substance offense” is subject to a sentencing enhancement. The Guidelines define “controlled substance offense” as “an offense under federal or state law * * * that prohibits the manufacture, import, expo rt, distribution, or dispensing of a controlled substance.” U.S.S.G. § 4B1.2(b) (emphasis added); see id. § 2K2.1 application note 1. The Guidelines do not, however, define “controlled substance.” When a federal defendant is subject to a controlled substance enhancement under the Sentencing Guidelines, does the term “controlled substance” in the Sentencing Guidelines refer only to those substances controlled under federal law or also include substances controlled under state law?