Part I of this Article summarizes the history of harmless-error review. Part II explains more fully the constitutional infirmities generated by conclusive mandatory presumptions and elemental misdescriptions, and demonstrates that the unique nature of these infirmities complicates the question of how courts should review them for harmlessness. It also examines the Supreme Court’s attempts to answer the questions of whether, and how, conclusive mandatory presumptions and elemental misdescriptions should be reviewed for harmlessness. In so doing, it focuses particularly on how these attempts have been undermined by the Court’s failure to take account of the structural rights undermined by these errors. Finally, Part III argues that the Constitution, relevant Supreme Court precedent, and policy considerations require application of the test specified in Justice Scalia’s opinion concurring in the judgment in Carella v. California when courts confront challenges to conclusive mandatory presumptions and elemental misdescriptions. It also contends that this test should apply on direct and collateral review.