Whether the term 'controlled substance' in the Career Offender Guideline refers to substances controlled under federal or state law, and whether the circuits are divided on the scope of the buyer-seller exception to drug conspiracy liability

1. Whether the term "controlled substance" in the definition of "controlled substance offense" in the Career Offender Guide line, § 4B1.2(b), refers to a substance controlled under federal law or under the law of the convicting jurisdiction, resolving the entrenched circuit split on this question ? 2. Whether the circuits are divided on the scope of the buyerseller exception to drug conspiracy liability under 21 U.S.C. § 846, and whether this case is an excellent vehicle to clarify when a single transaction suffices for conviction?