United States v. Marcus

Issue: Whether the Second Circuit departed from the Court's interpretation of Rule 52(b) of the Federal Rules of Criminal Procedure by adopting as the appropriate standard for plain-error review of an alleged ex post facto violation whether there is any possibility that the defendant could have been convicted based exclusively on conduct that took place before the enactment of the statutes in question.

Judgment: Reversed and remanded, 7-1, in an opinion by Justice Stephen Breyer on May 24, 2010. Justice Stevens dissented, and Justice Sotomayor took no part in the ruling.