Armed Career Criminal Act's "residual clause" struck down
An 8-1 in Jonnson v. U.S.. The ACCA provides for increased prison terms for an offender with three priors for certain offenses. The offenses are listed, with a residual clause, a crime that "otherwise involves conduct that presents a serious potential risk of physical injury to another." In construing that, the Court had held that you look at the legal definition of the offense, not at the facts of a particular offense, and so it covers flight from an officer and attempted burglary, but not DUI.
At issue here was a past conviction for possession of a short barreled shotgun. The majority rules, per Justice Scalia, that the whole thing is simply too vague to pass muster. The case law required courts to think of the "typical" offense of a given type, and guess how much danger that posed. That requirement was simply too vague to be constitutional.