Ervine Davenport was convicted of murder after appearing before the jury in shackles and behind a privacy screen. The state courts concluded that the trial court’s failure to identify a special need for shackling violated due process but treated the error as harmless. A federal court granted habeas relief, and the Sixth Circuit affirmed by applying a federal harmless-error test without first giving the state-court decision the deference required by federal habeas law. The Supreme Court reversed. It held that a federal habeas petitioner must satisfy both the deferential statutory standard governing state-court decisions and the separate requirement that the constitutional error had a substantial and injurious effect on the verdict. A federal court may not skip the statutory threshold simply because it believes the state court was wrong. The case was remanded for application of the correct two-part framework.