Law has long been conceived as a system and system involves order. However, the authors argue, for any system, even a legal system, to function it must also involve elements of disorder. This book investigates the systematic nature of a legal system, particularly as to the validity and interpretation of law, in four main areas: the elements of a legal system, relations among its elements, its relation to its environment and its relation to time. It is argued that, being both open and closed, self- and hetero-regulated, fixed and changing, complex and fluid, a legal system appears as a constant entangling of order and disorder. This innovative interdisciplinary study moves from traditional theory of legal system through systems theory to game theory, as well as drawing on sociology and anthropology of law.