The US Supreme Court on Tuesday ruled unanimously in Smith v. Spisak that the US Court of Appeals for the Sixth Circuit contravened the directives of the Antiterrorism and Effective Death Penalty Act (AEDPA) by extending Mills v. Maryland  to resolve in a habeas petitioner's favor questions that were not decided or addressed in Mills. The Sixth Circuit ruled that the jury instructions in defendant John Spisak, Jr's trial violated Mills by requiring unanimity in the finding that the aggravating circumstances outweighed the mitigating factors. In reversing the decision below, Justice Stephen Breyer wrote:

The Court of Appeals held the sentencing instructions unconstitutional because, in its view, the instructions, taken together with the forms, "required" juror "unanimity as to the presence of a mitigating factor" - contrary to this Court's holding in Mills v. Maryland. Since the parties do not dispute that the Ohio courts "adjudicated" this claim, i.e., they considered and rejected it "on the merits," the law permits a federal court to reach a contrary decision only if the state-court decision "was contrary to, or involved an unreasonable application of, clearly established Federal law, as determined by the Supreme Court of the United States." Unlike the Court of Appeals, we conclude that Spisak's claim does not satisfy this standard.