Along with discussions of global governance, global administrative law, and fragmentation, international legal scholars and other social scientists have increasingly engaged in debates over the causes and effects of global constitutionalization. These debates often suffer from imprecise and disparate definitions of the phenomena addressed, substitution of normative advocacy for scholarship, and analysis that is bounded within a particular type of international law or international legal structure. RULING THE WORLD? CONSTITUTIONALISM, INTERNATIONAL LAW AND GLOBAL GOVERNANCE (Cambridge University Press 2009) is the product of a three-year project that brought leading scholars together to create a comprehensive and integrated framework for understanding global constitutionalization. This paper, which will appear as the introduction to the volume, sets the stage for this project and establishes a coherent framework for analysis of global constitutionalization. We argue that global constitutionalization has three functions: (i) enabling the production of international law, (ii) constraining the production of international law, and (iii) supplementing domestic constitutionalization in order to respond to globalization. We explain how each of these functions is carried out in constitutional mechanisms, such as allocation of legislative authority, supremacy, stability, fundamental rights, judicial review, and accountability. As we do so, we contextualize and taxonomize some of the most important developments that have led to the current fascination with global constitutionalization. The functional approach to global constitutionalization developed in this paper provides a set of conceptual and analytical tools that can be used to identify and evaluate constitutional developments in various international domains. After outlining this approach, we provide a "constitutional matrix" that identifies which constitutional functions and mechanisms are found in various international legal regimes, including the UN, the EU, the WTO, and the human rights regime. This constitutional matrix provides a tool for comparison and analysis of different constitutional settlements. We conclude with some brief observations regarding constitutional pluralism, constitutional coordination, and constitutional synthesis
