The fragmentation of public international law is a long-observed phenomenon that demonstrates uneven normative and institutional development and evolution in inter-state relations. Separate legal norms and institutions have developed largely independently from one another, often instigated by non-identical groupings of states and in response to specific functional issues. The Proliferation of Courts and Tribunals has impacted upon long-standing generalist bodies such as the International Court of Justice (ICJ) and increased the potential for fragmentation and diversification of the law. In response, the United Nations International Law Commission (ILC), in a seminal study led by Martti Koskenniemi, advocates a tool-box of “Professional Techniques” (see section Professional Techniques Responding to Fragmentation) for international lawyers. These techniques seek first and foremost to ascertain the common intention of states parties to the relevant regimes in resolving normative conflicts, and include, in certain situations: the priority of particular or special norms (lex specialis) over general norms; the priority of a subsequent rule (lex posterior) replacing an earlier conflicting rule; the priority of particular “Relations of Importance” (see section Relations of Importance: Jus Cogens, Obligations Erga Omnes and Art 103 UN Charter), including jus cogens obligations; and the principle of “systemic integration” in treaty interpretation. There is a broader and growing literature looking further than doctrinal solutions to the fragmentation of public international law. Scholarship on Regimes and Regime Interaction focus on disparate sets of norms, decision-making procedures and organizations that have been developed to address functional issue-areas such as trade facilitation and human rights protection, and seek to understand how such regimes take one another into account during conflict resolution and in more general circumstances of lawmaking and implementation. Such regimes are sometimes disassociated from traditional public international law and involve private ordering operating transnationally as well as soft-law and informal rules. Drawing attention to conflicting and overlapping norms from both public and private legal realms, scholars writing about Pluralism draw on sociological insights about the domination of particular modes of behavior, assumptions and biases within regimes, and suggest that their conflicting rationalities can never cohere. By contrast, the general theme of Constitutionalism in public international law seeks to identify unifying principles and instruments––such as the United Nations Charter––in the world order. There are a wealth of empirical or analytical case studies from diverse international and transnational areas which often demonstrate that both perspectives––the disorder and flexibility of pluralism and the coherence and unity of constitutionalism––affect situations of fragmentation and, by extension, the perceived nature of international law as a system.
The topic of “fragmentation” has been the subject of much scholarly attention over the last decade, although the phenomenon has long been observed. Jenks 1953 recognizes that although the potential for conflicts between treaties is unavoidable and inherent to the international legal system, various solutions can be found in procedures and principles. In its seminal study on the “Fragmentation of International Law: Difficulties Arising From the Diversification and Expansion of International Law,” a Study Group of the International Law Commission (ILC), chaired by Martti Koskenniemi, reviews the available professional techniques for international lawyers confronting situations in which multiple international norms co-exist in relationships of interpretation or conflict. The ILC Analytical Study 2006 is a comprehensive analysis of conflicts between special law and general law (lex specialis derogare lege generali), conflicts between successive norms, relations of importance (such as jus cogens, obligations erga omnes and “conflict clauses” in treaties) and the harmonizing potential of treaty interpretation. It also notes the growth of “special regimes,” a term often used to describe a group of rules and principles concerned with a particular subject matter, and usually aided by specific administering institutions, diplomatic expertise and academic specialization. The ILC Conclusions 2006 are a succinct list of forty-two conclusions that have been collectively adopted by the ILC and taken note of by the United Nations General Assembly. The modern proliferation of international courts and tribunals has been a constant theme in the fragmentation literature, especially with respect to its possible threats to the coherence of international law, as discussed, for example, in Charney 1998. A critique informed by sociological understandings about a clash of rationalities underlying a conflict between regimes is provided in Fischer-Lescano and Teubner 2004, while Koskenniemi 2007 reviews the tensions between constitutionalism and pluralism. A body of work has moved beyond the traditional focus on adjudication and treaty interpretation in the fragmentation literature. The contributing authors (including Ralf Michaels and Joost Pauwelyn) to a study of “multi-sourced equivalent norms” consider the increase in situations of normative equivalence (rather than conflicts) between rules in different fields of international law in Broude and Shany 2011. The contributing authors (including James Crawford, Martti Koskenniemi and Gunter Teubner) to a study of diversity and concurrent activity between regimes consider relevant institutional, constitutional, sociological and doctrinal issues in Young 2012.
Broude, Tomer, and Yuval Shany, eds. Multi-Sourced Equivalent Norms in International Law. Oxford: Hart, 2011.
Considers “normative parallelism”––where similar or equivalent norms are developed within disparate international regimes. Spans useful case-studies including indigenous rights protections (Claire Charters), access to environmental information (Nikolaos Lavranos) and investment protection (Martins Paparinskis), as well as general analysis (Ralf Michaels and Joost Pauwelyn, Robert Howse).
Charney, Jonathan. “Is International Law Threatened by Multiple International Tribunals?” Recueil des cours 271 (1998): 101–382.
Collection of Charney’s timely Hague lectures that considered whether the coherence of international law was threatened by the increasing number of dispute settlement tribunals. Concludes his masterful study by observing that notwithstanding differences, the tribunals operate within the same fundamentals.
Fischer-Lescano, Andreas, and Gunther Teubner. “Regime-Collisions: The Vain Search for Legal Unity in the Fragmentation of Global Law.” Michigan Journal of International Law 25.4 (2004): 999–1046.
Responds to the preoccupation of coherence in the public international law literature by arguing that the fragmentation of international law reflects more than political pluralism; it reflects the collision of fundamentally contradictory rationalities. International law cannot be unified or hierarchized. See, in German language, Andreas Fischer-Lescano and Gunther Teubner, Regime-Kollisionen: Zur Fragmentierung des globalen Rechts (Frankfurt: Surhkamp, 2006).
ILC Analytical Study 2006, ILC Study Group on the Fragmentation of International Law. Fragmentation of International Law: Difficulties Arising from the Diversification and Expansion of International Law; Report of the Study Group of the International Law Commission, Finalized by Martti Koskenniemi. UN Doc A/CN.4/L.682 and Add.1 and Corr. 1. New York: International Law Commission, 2006.
The Study Group of the International Law Commission resolved that it would produce a “relatively large analytical study” by the chairman (Martti Koskenniemi), as well as “a condensed set of conclusions, guidelines or principles emerging from the studies and discussions in the Study Group.” This is the former document, which includes a comprehensive study of case-law and professional practice.
ILC Conclusions 2006. ILC, Report of the Study Group, Fragmentation of International Law: Difficulties Arising from the Diversification and Expansion of International Law: Conclusions (A/CN.4/L.702) (18 July 2006).
The Study Group of the International Law Commission resolved that it would produce a “relatively large analytical study” by the chairman (Martti Koskenniemi), as well as “a condensed set of conclusions, guidelines or principles emerging from the studies and discussions in the Study Group.” This is the latter document. Its forty-two recommendations were subsequently taken note of by the United Nations General Assembly.
Jenks, C. Wilfred. “Conflict of Law-Making Treaties.” British Year Book of International Law 30 (1953): 401.
Inspired by a distinguished professional practice (including as Director General of the International Labour Organisation) as well as keen academic observation, Jenks cites historic discussions of treaty-conflicts (including Grotius, Pufendorf and Vattel) and provides a modern perspective. Reviews diplomatic practice and relevant case-law and procedures for resolving conflicts.
Koskenniemi, Martti. “The Fate of Public International Law: Between Technique and Politics.” Modern Law Review 70.1 (2007): 1–30.
Provides a broad overview of the fragmentation of international law and argues that the principal academic responses to this phenomenon are constitutionalism and pluralism. The placing of the phenomenon of fragmentation within its historical and sociological context makes this a particular useful general overview of the topic.
Young, Margaret, ed. Regime Interaction in International Law: Facing Fragmentation. Cambridge, UK: Cambridge University Press, 2012.
This collection utilizes the concept of “regimes” from international law and international relations literature to describe functionally specialized groups of treaties and institutions such as human rights or trade law. Responding to existing approaches, it contains a variety of critical, sociological and doctrinal perspectives on fragmentation and regime interaction. Contributors include James Crawford, Martti Koskenniemi and Gunther Teubner.
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