Mahlangu, Siyabonga2021-08-302021-08-302020https://hdl.handle.net/10539/31541A thesis submitted in fulfilment of the requirements of the degree of Doctor of Philosophy in the School of Law of the University of the Witwatersrand, Johannesburg, Faculty of Commerce, Law and Management, 2020This thesis is a study of the Oudekraal principles and their development. In Oudekraal Estates (Pty) Ltd v City of Cape Town 2004 (6) SA 222 (SCA), the Supreme Court of Appeal fundamentally transformed the approach of South African law to the anomaly that an unlawful administrative act may have legal consequences. The court rejected past explanations for this phenomenon, such as the presumption of validity, the distinction between voidness and voidability, the theory of legal relativity and, where the courts have declined to set aside unlawful acts on grounds such as delay, judicial pragmatism. Instead, the court developed a principled approach by which it sought to strike a careful balance between the competing rule-of-law values of legality and certainty. Four principles emanating from this seminal judgment are identified in the thesis. These are that an unlawful act may have legal effect for so long as it has not been set aside; that the legal effect depends on whether the validity of an originating act is a precondition for the validity of the subsequent act; that an unlawful act which compels a person to do or not to do something must be valid, and a person affected by it is entitled to challenge its invalidity collaterally; and that the court reviewing an unlawful act has discretion to refuse the remedy of setting aside even if a ground of review has been established. The thesis investigates how the courts since Oudekraal have interpreted, applied and developed these four principles. It concludes that there is an interplay between the various principles. In this interplay the Constitutional Court has recently tended to emphasise the value of legality over that of certainty, resulting in a lack of clarity as to what it means for an unlawful act to have legal effect prior to its being set asideenUCTDLEGALITY AND CERTAINTYOUDEKRAAL PRINCIPLESSDG-16: Peace, justice and strong institutionsThesisUniversity of the Witswatersrand, Johannesburg