Over the past fifteen years, the Constitutional Court and Supreme Court of Appeal have held that objectively invalid administrative and executive decisions remain legally effective unless they are set aside in review proceedings The rule has emerged from balancing two competing principles of the rule of law: on the one hand, legality in that government action must be lawful; on the other, certainty in that if government decisions could be ignored without recourse to the courts that could undermine the orderly functioning of government and the administration of justice The courts have applied a similar rule in respect of court orders: all court orders are binding unless they are overturned on appeal or through rescission proceedings, save for one exception-where a judge issues an order outside of his or her authority or competence, it is invalid and not binding In this article I trace the emergence and development of this exception in the jurisprudence and offer some preliminary justifications for why the courts treat invalid, authority-related court orders differently from invalid government decisions, thereby striking a different balance between legality and certainty I then provide guidance as to how courts ought to determine whether a court order was issued with or without authority and explore the limits of the exception, particularly in respect of its application to orders issued by South Africa's apex Court