Whether the term 'controlled substance' is defined by the drug schedules that existed at the time of the prior predicate conviction, or the drug schedules that exist at the time of the federal offense or federal sentencing

QUESTION PRESENTED In federal sentencing, the U.S. Sentencing Guidelines typically call for a higher advisory Guidelines range if the defendant has been convicted of a prior “controlled substance offense.” But in defining the term “controlled substance,” two circuit splits have developed. 1. Is the term “controlled substance” defined by the drug schedules that existed at the time of the prior predicate conviction, or the drug schedules that exist at the time of the federal offense or federal sentencing? 2. Does the term “controlled substance” refer only to those substances controlled under federal law, or does it also include separate substances controlled only under state-law drug schedules? i