Should law be conceived of as singular or plural? Globalisation has brought profound changes to the traditional approaches to organising cases of diversity, both social and institutional. Even the theories of federalism and of legal pluralism need updating. Nowadays, global law is pervaded both by the trend towards unification, as in the field of human and fundamental rights, and by the opposite trend towards diversification, which is expressed primarily in the market, especially in contractual instruments. But there is no shortage of paradox and contradiction, both in the former field and in the latter. Even the gradual consolidation of judge-made law, which is replacing legislative macro-decisions on the global scene, seems to be suspended in limbo between unification and differentiation.