Per incuriam
Per incuriam, literally translated as "through lack of care", refers to a judgment of a court which has been decided without reference to a statutory provision or earlier judgment which would have been relevant. The significance of a judgment having been decided per incuriam is that it does not then have to be followed as precedent by a lower court. Ordinarily, in the common law, the rationes of a judgment must be followed thereafter by lower courts hearing similar cases. A lower court is free, however, to depart from an earlier judgment of a superior court where that earlier judgment was decided per incuriam.
The Court of Appeal in Morelle Ltd v Wakeling [1955] 2 QB 379 stated that as a general rule the only cases in which decisions should be held to have been given per incuriam are those of decisions given in ignorance or forgetfulness of some inconsistent statutory provision or of some authority binding on the court concerned: so that in such cases some part of the decision or some step in the reasoning on which it is based is found, on that account, to be demonstrably wrong.
In R v Northumberland Compensation Appeal Tribunal ex parte Shaw [1951] 1 All ER 268, a divisional court of the King's Bench division declined to follow a Court of Appeal decision on the ground that the decision had been reached per incuriam as a relevant House of Lords decision had not been cited to the Court of Appeal.
Some academic critics have suggested that Polemis [1921] 3 KB 560 was decided per incuriam as it did not rely upon the earlier decision in Hadley v Baxendale.