Cette thèse cherche à analyser de manière critique le débat sur la fragmentation du droit international tel qu'il est apparu à la fin des années 1990. Débattre de la fragmentation, c'est débattre du sort réservé au droit international en raison de la prolifération des institutions et des modes de pensée spécialisés. De l'extérieur, le droit international public semble dépassé par les structures dynamiques et informelles de gouvernance privée tandis que de l'intérieur, la croissance continue de ses branches spécialisées pose la question de savoir s'il existe encore un tronc commun ou un noyau dur autour duquel la discipline serait unifiée. Du point de vue interne, donc, la multiplication des règles et des institutions spécialisées l'ont perçue comme un danger qui doit -et qui peut- être évité, tant et aussi longtemps que l'on assure la cohérence ou l'unité d'interprétation du droit international général et de ses branches spécialisées, travail qui incombe à la dogmatique juridique ainsi qu'à la pratique juridictionnelle. Du point de vue externe, l'apparition des régimes de régulation fonctionnels témoigne plus simplement de l'impact de la mondialisation sur le droit (international) et de la façon dont celui-ci s'adapte à celle-là au travers de nouveaux processus déformalisés de juridisation. L'objectif de cette thèse est de montrer qu'aucune des positions ne peut l'emporter de manière décisive sur les autres, de comprendre pourquoi et d'analyser les conséquences de cette indétermination. / The aim of this PhD is to critically analyse the debate on the fragmentation of internationallaw as it émerged in the late 1990s. This debate is a debate about the fate of international law in light of the proliferation of specialised institutions and multiple modes of thinking. From the outside, public international law seems sidelined by the informaI structures of private governance while, from the inside, its functional differentiation raises the question of whether there is a centre around which the discipline would still be unified. From an internaI viewpoint, thus, the multiplication of specialised mIes and institutions looks like a dangerous evolution that should -and can- be avoided, as long as international lawyers ensure a consistency in the interpretation ofboth general internationallaw and specialised regimes. From an external viewpoint, the growth of regulatory regimes seems to reflect the impact of globalisation on (international) law and the way law responds to the functional difTerentiation of global society. The objective of this the sis is to show that none of the positions can prevail decisively over the others, to understand why, and to analyse the consequences of such an indetermination.

Cette thèse se donne pour objectif de mesurer la portée actuelle des principales conceptualisations de Hans Kelsen dans la doctrine et le droit positif international. Pour ce faire, cette étude envisage une reconstruction de la pensée du juriste viennois dans la discipline spécifique de droit international placée à la lumière du contexte de l'évolution normative, institutionnelle et politique de l'ordre juridique international. L'ambition est ainsi de faire ressortir l'originalité de son approche du phénomène international et sa portée actuelle. Il s'agira aussi d'en mesurer les limites et les possibilités de dépassement. / His thesis has the objective of measuring the current scope of the main conceptualizations of Hans Kelsen in the doctrine of international law and international positive law. The study envisages a reconstruction of the thought of the Viennese lawyer in international law placed in the light of the context of the evolving normative, institutional and politic of the international legal order. This is the gift of bringing out the originality of his thought, to measure the presence of the positivist approach in debate of the unity of international law.

Le droit international évolue et se traduit par une augmentation des normes, des organisations et des juridictions internationales, faisant craindre une fragmentation du droit international au sein de l’ordre juridique international. L’ordre juridique international s’entend, au sens large, comme le droit international régissant la société internationale. Celui-ci englobe les ordres juridiques internationaux spécialisés, composés des organisations internationales. Chacune d’entre elles comprend une juridiction ou un tribunal arbitral. La problématique de cette thèse est de déterminer, par l’étude du pluralisme juridique international, si ce risque de fragmentation du droit international est avéré ou non. Elle se fonde, pour ce faire, sur une analyse systémique des ordres juridiques internationaux, pour établir si ceux-ci établissent des rapports de droit entre eux, ainsi que sur une analyse normative des ordres juridiques, afin de déterminer si chacun d’entre eux a une cohérence propre. Dans une première partie, il est démontré que le pluralisme juridique international semble désordonné, induisant un risque de fragmentation du droit international, en raison, d’une part, de la multiplication des ordres juridiques internationaux et, d’autre part, de leur carence institutionnelle. Il est démontré ensuite, dans une seconde partie, que le pluralisme juridique international s’ordonne grâce à la mise en cohérence du droit international par les juges internationaux. Ceux-ci coordonnent la jurisprudence internationale grâce à leur jurisdictio (dire le droit) et érigent un véritable pouvoir juridictionnel international à travers leur imperium (rendre une décision obligatoire). / International law evolves at a rapid pace, and results in a strong increase in norms, organizations and international courts, raising increasing fears about a fragmentation of international law within the international legal order itself. The international legal order is defined, in the broadest sense of the term, as international law aimed at governing international society. This includes specialized international legal systems, made up of a number of international organizations ; each one including a court or an arbitral tribunal. The aim of this thesis is to determine, through the study of international legal pluralism, weather this foreseen risk of a possible fragmentation of the international law is, in the end, proven or not. In order to fulfill this aim, our work is based, on the one hand, on a systemic analysis of international legal orders, this in order to determine whether these bodies establish legal relationships between themselves, and on the other hand, on a normative analysis of legal systems, to determine this time whether each one sets up, or not, its proper inner coherence.In the first part, we show that the international legal pluralism seems to be uncoordinated, inducing a risk of fragmentation of international law, this due, in part, to the proliferation of international legal orders and, and in other part, to their lack of institutional ground. In the second part, we aim at proving that the international legal pluralism finds best its balance when international law is put into practice by international judges. They coordinate international jurisprudence through their jurisdictio (apply the law) and set out the boundaries of a true international judicial power through their imperium (to pronounce a binding decision).

Esta dissertação concentra suas investigações nas contramedidas do direito internacional geral e da Organização Mundial do Comércio (OMC). No âmbito do direito internacional, estudou-se a essência política da sociedade internacional descentralizada, bem como a tendência do processo de fragmentação do direito internacional em direção a regimes mais regulados pelo direito. Além disso, investigou-se a tentativa de ampliação da normatização das contramedidas por meio do Projeto de Artigos sobre Responsabilidade Internacional do Estado de 2001. No âmbito do regime especial da OMC, analisou-se o maior adensamento jurídico das contramedidas como ponto culminante na fase de implementação das decisões no sistema de solução de controvérsias da OMC. Com base na avaliação sobre a necessidade de reforma do instituto das contramedidas da OMC, foram pesquisadas as principais propostas para sua modificação, buscando-se identificar a tentativa de redução do espaço político. A hipótese deste trabalho partiu da afirmação sobre a existência de uma tendência evolutiva no direito internacional geral e na OMC no que tange ao aumento da juridicidade do instituto das contramedidas. Entretanto, essa hipótese confirmou-se apenas parcialmente, pois a tentativa de aprimorar a regulamentação jurídica do instituto das contramedidas ocorre em meio à permanência de elementos políticos. / This thesis focused on countermeasures in general International Law and in the World Trade Organization (WTO). Regarding International Law, the thesis studied the political foundation of the decentralized international society, as well as the trend of fragmentation of International Law towards law-based regimes. Moreover, this thesis researched the attempt to regulate countermeasures through the Draft Articles on Responsibility of States for Internationally Wrongful Acts. Regarding the WTO special regime, the thesis analyzed its more law-based countermeasure as the last stage in the implementation of decisions in the WTO dispute settlement system. Based on the necessity of WTO countermeasures reform, the thesis investigated the main reform proposals, seeking to identify the attempt to reduce the political interference. The hypothesis of this research is the tendency towards a more law-based countermeasure in general International Law and in the WTO. However, this hypothesis has only been partially confirmed because political elements do not disappear despite the attempt to increase the legality of countermeasures.

Esta dissertação concentra suas investigações nas contramedidas do direito internacional geral e da Organização Mundial do Comércio (OMC). No âmbito do direito internacional, estudou-se a essência política da sociedade internacional descentralizada, bem como a tendência do processo de fragmentação do direito internacional em direção a regimes mais regulados pelo direito. Além disso, investigou-se a tentativa de ampliação da normatização das contramedidas por meio do Projeto de Artigos sobre Responsabilidade Internacional do Estado de 2001. No âmbito do regime especial da OMC, analisou-se o maior adensamento jurídico das contramedidas como ponto culminante na fase de implementação das decisões no sistema de solução de controvérsias da OMC. Com base na avaliação sobre a necessidade de reforma do instituto das contramedidas da OMC, foram pesquisadas as principais propostas para sua modificação, buscando-se identificar a tentativa de redução do espaço político. A hipótese deste trabalho partiu da afirmação sobre a existência de uma tendência evolutiva no direito internacional geral e na OMC no que tange ao aumento da juridicidade do instituto das contramedidas. Entretanto, essa hipótese confirmou-se apenas parcialmente, pois a tentativa de aprimorar a regulamentação jurídica do instituto das contramedidas ocorre em meio à permanência de elementos políticos. / This thesis focused on countermeasures in general International Law and in the World Trade Organization (WTO). Regarding International Law, the thesis studied the political foundation of the decentralized international society, as well as the trend of fragmentation of International Law towards law-based regimes. Moreover, this thesis researched the attempt to regulate countermeasures through the Draft Articles on Responsibility of States for Internationally Wrongful Acts. Regarding the WTO special regime, the thesis analyzed its more law-based countermeasure as the last stage in the implementation of decisions in the WTO dispute settlement system. Based on the necessity of WTO countermeasures reform, the thesis investigated the main reform proposals, seeking to identify the attempt to reduce the political interference. The hypothesis of this research is the tendency towards a more law-based countermeasure in general International Law and in the WTO. However, this hypothesis has only been partially confirmed because political elements do not disappear despite the attempt to increase the legality of countermeasures.