21 U.S.C. § 841(A)(1) makes is a crime to "knowingly or intentionally .. . manufacture, distribute, or dispense, or possess with intent to manufacture, distribute, or dispense, a controlled substance." Does the term "knowingly or intentionally" require the Government to prove that the defendant knew what substance he or she was distributing in order to obtain enhanced penalties pursuant to subsection (b) of the statute?

21 U.S.C. § 851 provides that where a defendant has a prior "felony drug offense," and the distribution of a drug results in serious bodily injury, a life sentence must be imposed. Does the determination of whether a prior offense qualifies under the statute require that determination be made by the jury, or by a district court at sentencing?

Whether the term 'knowingly or intentionally' requires the Government to prove that the defendant knew what substance he or she was distributing to obtain enhanced penalties