Greer v. United States

This case asked how federal appeals courts should handle unpreserved errors after Rehaif clarified that, in felon-in-possession cases, the government must prove the defendant knew he was a felon. The Court held that on plain-error review, an appellate court may look beyond the trial record, and a defendant is not entitled to relief without showing a reasonable probability that the outcome would have been different if the Rehaif error had not occurred.