Supreme Court Decision Syllabus (scotus)

 These cases concern the application of the Armed Career Criminal Act to state drug convictions that occurred before recent technical amendments to the federal drug schedules. ACCA imposes a 15-year mandatory minimum sentence on defendants who are convicted for the illegal possession of a firearm and who have a criminal history thought to demonstrate a propensity for violence. As relevant here, a defendant with “three previous convictions” for “a serious drug offense” qualifies for ACCA’s enhanced sentencing. 18 U. S. C. §924(e)(1). For a state crime to qualify as a “serious drug offense,” it must carry a maximum sentence of at least 10 years’ imprisonment, and it must “involv[e] . . . a controlled substance . . . as defined in section 102 of the Controlled Substances Act.” §§924(e)(1), (2)(A)(ii). Under the categorical approach, a state drug offense counts as an ACCA predicate only if the State’s definition of the drug in question “matche[s]” the definition under federal law. Shular v. United States, 589 U.