In 1985, Robert Van Hook robbed and killed another man. He confessed to the crime, waived his right to a jury trial, and was convicted and sentenced to death. The Ohio state courts affirmed the conviction and sentence on direct appeal and later denied post-conviction relief. Van Hook's federal application for a writ of habeas corpus was denied by the district court, but a panel of the U.S. Court of Appeals for the Sixth Circuit three times reversed and directed that the writ be issued, relying on different grounds each time. The full Sixth Circuit, sitting en banc, twice vacated the panel decision and remanded for further consideration, but the panel's third decision, holding that Van Hook's lawyers had failed to provide effective representation in the penalty phase of his trial because they did not fully comply with guidelines for the performance of defense counsel in death penalty cases promulgated by the American Bar Association (ABA) in 2003, was not reviewed en banc.
The Supreme Court granted the petition for a writ of certiorari and, without setting the case for argument, reversed the Sixth Circuit Court's decision in a unanimous per curiam opinion. It held, first, that the lower court erred both in assessing the adequacy of counsel's performance in the mid-1980s based on "guidelines" promulgated almost 20 years later and in treating those guidelines as "inexorable commands with which all capital defense counsel ‘must fully comply'" rather than "merely as evidence of what reasonably diligent attorneys would do." The Court made a particular point of noting that it was not endorsing any use of the ABA guidelines in deciding whether a criminal defendant has been denied effective assistance of counsel.
Second, the Court rejected Van Hook's argument that he had been denied effective assistance of counsel even under the standards of professional conduct that prevailed at the time of his trial. It noted that counsel had made extensive and timely investigation of Van Hook's background and had presented substantial evidence, including expert testimony, about his traumatic childhood and adolescence. The decision not to dig further to uncover still more mitigating evidence, which the Court suggested would have been merely cumulative and the collection of which would have distracted counsel from more important duties, fell "well within the range of professionally reasonable judgments."
Justice Alito joined in the opinion of the Court and also filed a concurring opinion.