This Article uses social systems theory to examine the increased reliance on a distinction between substantive and procedural international law to resolve cases involving a conflict between jus cogens and state immunity. This presents the problem of an evolutionary relationship between international law and the complex differentiation of world society. International law is shown to be structurally related to the segmentary differentiation of states that underwrites modern society's functional

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... fferentiation. At the same time, it is shown to be structurally related to the increasing formulation of global norms that result from advanced functional differentiation. The Article then turns to examining the substantive/procedural law distinction as a solution to this dual functional reference problem. The distinction is shown to not only maintain the autopoiesis of law under these difficult conditions, but to also secure law's continued functional relevance in globalized society. This functionalist perspective is used to expose differences in the self-description and operation of international law, to point out how law has been blind to its own coding, and to highlight opportunities for programming law to respond in a more constructive manner to the challenges of globalization.