Comparativisim is here conceived as a universal method of analysis of social systems, applicable specifically to systems of concepts. From this angle, legal systems appear to be contingent and evolving. The comparative method allows us to reveal the constants on the temporal and spatial level. In a way, it is both the “transhistorical” and the “transnational” dimension of law which emerges (Mireille Delmas-Marty, Ordering Pluralism. A Conceptual Framework for Understanding the Transnational Legal World, Oxford : Hart, 2009). The perspective of the judge becomes then the reflection of the legal system of the society-world, which we designate at present by the concept of global law (Global Law, Weltrecht). Global law transforms perspectives. Recognition of the plurality of systems produces a common question: “From the perspective of which legal system do you view the world?” This question leads to an examination of the uniqueness of the legal phenomenon, through the problem of the social function of law (Niklas Luhmann, Das Recht der Gesellschaft [The Law of Society], Frankfurt am Main: Suhrkamp, 1993). The different approaches of comparative law thus contribute to the understanding of global law, of a law without territorial or state allegiance, of the law of a functionally-differentiated society, without summit or centre, of the fragmented law described by Gunther Teubner (Verfassungsfragmente. Gesellschaftlicher Konstitutionalismus in der Globalisierung [Constitution Fragments. Societal Constitutionalism in Globalisation], Berlin: Suhrkamp, 2012). Comparativism then allows us to explore the stimulating hypothesis of the transition from a state constitutionalism to a societal constitutionalism. Thus emerges the idea of a universal law, no longer unified around a state constitution, but differentiated in distinct transnational legal systems, the paradigm of which could be the transnational law of the economy (lex mercatoria), the foundation of a global economic constitution. There is therefore, if we want to admit that scientific truths have an aspect of universality and timelessness, a similarity between the comparativist method and the very idea of a legal science.