The concept of judicial law-making impacts on the extent, meaning and scope relationship between the legislature, the executive and the judiciary. It is an integral function of the courts while its shape, meaning and nature seem to lack sufficient formulation and articulation, which results in an inherent problem regarding its legitimacy. This study examines the legitimacy and the working of the South African constitutional judicial law-making concepts. Its effect on the constitutional relationships between all three branches of government is scrutinized. In order to fully probe this concept, its impact and application on the separation of powers, judicial review, constitutional deference and mandatory minimum sentences becomes inevitable. The introductory part of this study looks at origins and historical development of the separation of powers doctrine and its application under the 1996 South African Constitution. The latter part focuses on the nature and the scope of judicial review, judicial law-making, constitutional deference and mandatory minimum sentences with a view establishing the impact of these concepts in our judicial law-making. The development of these concepts by South African courts, and what seems to be the lack of formulation and articulation of South African constitutional judicial law-making which raises questions regarding its legitimacy is probed. This research recommends that it is of the utmost importance that South Africa develops its own unique and comprehensive doctrine of separation of powers. The Constitution further requires reforms in order to clarify the extent to which the courts can go when formulating laws and public policy in the interests of justice, and whether the interests-of-justice test is capable of delivering a well-informed outcome in developing this jurisdiction’s laws. South African jurisprudence also needs to be developed in empowering the legislature to make laws which are constitutionally compliant without making the courts the sole expositor of the Constitution. Lastly, the extent to which the legislature can enact certain laws must be redefined, which on face value might seems to be encroaching into the courts’ independence and authority. / Criminal and Procedural Law / LL. D. (Criminal and Procedural Law)