In 1896, the Supreme Court ordered new trials for two men convicted of seeking to aid Cuban revolutionaries seeking to secure independence from Spain. In so doing, the Court invented the doctrine of plain error review, an exception to usual rule that appellate courts mustn’t consider arguments that weren’t raised below. So writes Judge Oldham of the Fifth Circuit, tracing the doctrine’s waxings and wanings and concluding the Supreme Court has allowed it to overwax of late.