In the following contributions, authors investigate interconnected aspects of the problem of democratic deficit in global constitutionalism. The commonly shared question is: to what extent, if any, a global (or cosmopolitan) shift of international law can proceed absent a transnational democratic check? Not all scholars are convinced that this is an actual problem. Many think, instead, that a 'division of labor' is to be recognized between national and regional/international legal levels. It is a common conviction for authors present hereafter, that detachment of international law production from constituent will, as well as from a democratic framework, does indeed undermine constitutional legitimacy. Furthermore, it opens to forms of domination that affect also state's democratic institutions from within. What is the way out from this deadlock? How is it possible to tame global constitutionalism in order to avoid a global Leviathan? The collection of essays here presented attempts to conceptualize some of the central challenges affecting contemporary patterns of legal dispersion and fragmentation. There unfolds a coherent thread which, starting from a modern Kantian understanding of the problem, it moves to the discussion of issues of constitutional pluralism, institutional legitimacy and the risk of tyranny. It follows the analysis of the role of China and the EU, two of the most important actors, even though perhaps at the opposite pole of the global constitutional project.