In This Article Expand or collapse the "in this article" section International Constitutional Law

  • Introduction
  • General Overviews
  • Sectoral Constitutions of International Institutions
  • UN Charter as a Constitution
  • WTO Law as International Constitutional Law
  • Multilevel Dimension of Constitutionalism
  • Constitutional Hierarchies in International Law
  • Common Values and Interests of the International Community
  • International Human Rights as Constitutional Law
  • Democratic Legitimacy as a Constitutional Concern
  • Tradition of the Constitutional Idea in International Law Scholarship
  • General Critique of the Constitutionalist Paradigm

International Law International Constitutional Law
Thomas Kleinlein, Anne Peters
  • LAST REVIEWED: 12 May 2017
  • LAST MODIFIED: 22 February 2018
  • DOI: 10.1093/obo/9780199796953-0039


The notion “international constitutional law” refers to norms of public international law with a constitutional character or function. Thus understood, international constitutional law can be divided into three broad subcategories: (1) fundamental norms which serve a constitutional function for the international legal system at large, (2) norms which serve as constitutions of international organizations or regimes, and (3) norms which have taken over or reinforce constitutional functions of domestic law. Already the fundamental rules of the Westphalian state system that allocate competences and delineate spheres of state jurisdiction could be referred to as constitutional law of the international legal order. Since then, new layers of constitutional law have been added, transforming international law from an interstate order into an order which is also committed to the international community and to the individual. These added contents strengthen the autonomy of international law vis-à-vis state sovereignty. Still, compared to domestic constitutions, the participation of individuals, their status activus in international legal processes, is extremely underdeveloped. The constituent instruments of international organizations constitute a second category of international constitutional law. They establish international organizations as legal entities; define their purposes, powers, and fundamental principles; establish rules on the admission of new members; and set up special procedures and majority rules for amendment. A “constitutional” understanding of institutional law is ambivalent. On the one hand, this understanding characterizes founding treaties as “living instruments” and thereby justifies a dynamic interpretation of their powers and this may bolster the organizations’ autonomy and effectiveness. On the other hand, it may restrict the ambitions of international organizations in the light of human rights concerns or based on constitutional doctrines such as institutional balance or separation of powers and thereby strengthen their accountability. Finally, certain norms of international law may be qualified as constitutional because they function as supplementary constitutional law in the domestic context. This is obvious for international human rights law, which constrains state action that risks violating those norms. Beyond human rights, international law influences domestic governance to an unprecedented extent. For example, it arguably prescribes that new states can only come into being if they are organized in a democratic fashion. Some regard WTO law and international investment law as a “second line of constitutional entrenchment” to grant economic freedoms of market actors. This market-enabling function of international economic law is in turn criticized as overly neoliberalist “new constitutionalism” by others.

General Overviews

Concepts related to international constitutional law are “constitutionalization” and “global constitutionalism.” Some scholars claim that international law or some subsystems are progressively developing into an order which resembles a constitutional order in substantive and structural terms (“constitutionalization”; see also Constitutional Hierarchies in International Law). “Global constitutionalism” is an outlook which serves as a heuristic tool, as a vocabulary of critique, and as a carrier of a normative agenda. Dobner and Loughlin 2010 is primarily concerned with the fate of the constitutionalist tradition in the light of a perceived decline of the nation-state. Starting from the concept of constitution familiar from the democratic nation-state, some contributors even doubt that the concept can be meaningfully applied to refer to international law norms. In general, the question of how to “translate” the different elements and dimensions of the constitutionalist tradition to contexts beyond the state is a central issue of the debate. Both Dunoff and Trachtman 2009 and Klabbers, et al. 2011 develop constitutionalist perspectives on various aspects of the actors and structures of the international order. In this regard, they represent a general trend: the more recent debate on global constitutionalism focuses less on common values (see Common Values and Interests of the International Community) and rather more on actors and structures, the exercise of authority beyond the state (see Sectoral Constitutions of International Institutions), and legitimacy concerns (see Cohen 2012 and Democratic Legitimacy as a Constitutional Concern). Several journal articles survey the meanings of “constitutionalization” in international law and/or analyze features of constitutionalist approaches (Diggelmann and Altwicker 2008 and Kleinlein 2012 suggest different versions of a social constructivist approach; see also Ruiz Fabri and Grewe 2004, cited under Tradition of the Constitutional Idea in International Law Scholarship for a critical historical overview). Schwöbel 2011 scrutinizes the debate on global constitutionalism from the perspective of critical legal theory. The relationship between constitutionalization and fragmentation in international law and law beyond the state as well as the existence of constitutional fragments represents another central issue in the debate, as exemplified in Jakubowski and Wierczyńska 2016, Peters 2017, and Teubner 2012. The current debate on global constitutionalism, which started in the 1990s, is only slowly de-westernizing (see Suami, et al. 2018 and Bhandari 2016, the latter cited under WTO Law as International Constitutional Law).

  • Cohen, Jean L. Globalization and Sovereignty: Rethinking Legality, Legitimacy, and Constitutionalism. Cambridge, UK: Cambridge University Press, 2012.

    DOI: 10.1017/CBO9780511659041

    Challenges both the cosmopolitan notion that sovereign equality of states is outdated and a “hermeneutics of suspicion.” Develops a theory of a dualistic world order consisting of an international society of states and global governance institutions. Advocates constitutional pluralism as the conceptual framework for the “further constitutionalization” of international law and global governance.

  • Diggelmann, Oliver, and Tilmann Altwicker. “Is There Something Like a Constitution of International Law? A Critical Analysis of the Debate on World Constitutionalism.” Zeitschrift für ausländisches öffentliches Recht und Völkerrecht 68 (2008): 623–650.

    Analyzes especially the use of constitutional language. Discerns two blind spots: disintegrating trends and linkages to the common concept of constitution. Considers the constitutionalist approach to be explanatory and strategic. Suggests a social constructivist approach: world constitutionalism as an institution may contribute to changing the common perception of international relations.

  • Dobner, Petra, and Martin Loughlin, eds. The Twilight of Constitutionalism? Oxford: Oxford University Press, 2010.

    DOI: 10.1093/acprof:oso/9780199585007.001.0001

    Starts from the observation that globalization causes an “erosion of statehood” which seriously challenges the established processes of domestic democratic constitutionalism. Political scientists, sociologists, and legal scholars revisit the achievements, analyze the metamorphosis, and debate the future prospects of constitutionalism, in particular its translatability to contexts beyond the state.

  • Dunoff, Jeffrey L., and Joel P. Trachtman, eds. Ruling the World? Constitutionalism, International Law, and Global Governance. Cambridge, UK: Cambridge University Press, 2009.

    DOI: 10.1017/CBO9780511627088

    First part deals with conceptional issues. The editors take the lead, followed by David Kennedy’s skeptical piece and by Paulus on constitutional principles. Second part addresses the UN, the EU, and the WTO. Third part discusses “crosscutting issues”: human rights, cosmopolitan constitutionalism (Kumm), pluralism, and democratic legitimacy.

  • Jakubowski, Andrzej, and Wierczyńska, Karolina, eds. Fragmentation vs the Constitutionalisation of International Law: A Practical Inquiry. London: Routledge, 2016.

    This edited volume picks up on the older observation that constitutionalization and fragmentation are interrelated developments in international law. Different parts of the book address fragmentation as a challenge for and as a means of constitutionalization. As suggested by the subtitle, the focus is on a “practical inquiry” in different areas of international law. Also comprises a more theoretical part on constitutionalization “as a claim.”

  • Klabbers, Jan, Anne Peters, and Geir Ulfstein. The Constitutionalization of International Law. Oxford: Oxford University Press, 2011.

    Asserts that constitutionalization is actually going on in international law. Develops a critical constitutionalist perspective. Klabbers and Ulfstein analyze constitutional functions of lawmaking and adjudication. Peters discusses the role of various actors in the global constitutional community, develops a model of “dual democracy,” and discusses the constitutionalist paradigm in general. Originally published in 2009; the 2011 edition contains contributions of critics (Joel Trachtman, Jean Cohen, and others) and responses by the authors.

  • Kleinlein, Thomas. “Between Myths and Norms: Constructivist Constitutionalism and the Potential of Constitutional Principles in International Law.” Nordic Journal of International Law 81 (2012): 79–132.

    DOI: 10.1163/157181012X638052

    Defends international constitutionalism. Sorts phenomena of international constitutional law and surveys particular features of constitutionalist approaches. Proposes constructivist approach referring to constitutional principles which emerge on the basis of processes of identity change and argumentative self-entrapment. Gives example of how these principles operate in international law. (Builds on selective chapters of Kleinlein 2012, cited under Constitutional Hierarchies in International Law.)

  • Peters, Anne. “Constitutionalization.” In Fundamental Concepts for International Law: The Construction of a Discipline. Edited by Jean d’Aspremont and Sahib Singh. Cheltenham, UK: Elgar, 2017.

    Shows that the constitutionalization of and within international law is a fragmented process which moreover engages domestic constitutional law. It is not bringing about a “super-constitution” over and above domestic law and all international subfields. Explains, after clarifying the key terms, notably constitutionalization, constitutionalism, and constitutional law, the sectoral constitutionalization of various international organizations and the constitutionalization of the private (economic) realm. Concludes that we find (only) constitutional fragments.

  • Schwöbel, Christine E. J. Global Constitutionalism in International Legal Perspective. Leiden, The Netherlands, and Boston: Martinus Nijhoff, 2011.

    DOI: 10.1163/ej.9789004191150.i-205

    Critically scrutinizes the debate on global constitutionalism. Assigns contributions to four “dimensions” (social, institutional, normative, and analogical). Spots five “key themes” (limitation of power, individual rights, etc.) and traces their intellectual origins. Situates the debate in the liberal tradition and criticizes its inherent limitations. Advocates an “organic” global constitutionalism.

  • Suami, Takao, Mattias Kumm, Anne Peters, and Dimitri Vanoverbeke, eds. Global Constitutionalism from European and East Asian Perspectives. Cambridge, UK: Cambridge University Press, 2018.

    Confronts global constitutionalism (which has been developed in Europe and which is perceived to be Eurocentric) with an East Asian critique. Thereby pursues a dual objective: it seeks, firstly, to refine, reshape, or even downsize the cognitive framework, and thereby, secondly, to promote or adjust its normative agenda.

  • Teubner, Gunther. Constitutional Fragments: Societal Constitutionalism and Globalization. Oxford: Oxford University Press, 2012.

    DOI: 10.1093/acprof:oso/9780199644674.001.0001

    Not a book about international constitutional law but about constitutions beyond the nation-state. Points to corporate human rights scandals and other examples of modern concerns. Criticizes the state-and-politics-centricity of traditional constitutionalism and presents an alternative sociological approach, a model of transnational, societal constitutional fragments. Identifies transnational regimes, particularly in the private area, as the new constitutional subjects in a global society.

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