This thesis analyses the legitimacy of the WTO dispute settlement system, especially in the context of disputes involving questions concerning environmental protection. It argues that since the early 1990s, such disputes have posed important challenges to the legitimacy of the WTO. From the legal point of view, they have fuelled a lively doctrinal debate on fragmentation of international law and the role of non-WTO norms in the WTO dispute resolution mechanism. The thesis conceives legitimacy as a notion consisting of various interlinked components, including social, substantive, formal and procedural ones, and analyses the operation of the WTO dispute settlement system in light of these criteria. It shows that the compulsory but materially restricted jurisdiction of the WTO dispute settlement limits its ability to solve disputes involving non-trade interests and legal norms. The dissertation argues, however, that some of the ensuing problems could be remedied if the WTO dispute settlement system approached international environmental law in a more constructive, consistent and transparent manner. Turning to the formal and procedural elements of legitimacy, the thesis conceives the situation of the WTO dispute settlement system as a dilemma between the pressure to improve substantive legitimacy by considering environmental norms and interests, and the need to observe the limits of its judicial function. It explores tensions at the boundary between the WTO and its Member States, arguing that only limited potential exists to enhance the authority of the WTO dispute settlement through 'importing' substantive legitimacy. Finally, the dissertation highlights institutional and systemic problems arising from fragmentation of international law. Using the relationship between the WTO and the international climate change regime as an example, it concludes that the WTO dispute settlement system's legitimacy challenge involves two dimensions. Certain unexploited potential exists to improve the situation through the judicial techniques at the disposal of the WTO dispute settlement system. However, the more profound and systemic problems are incapable of solution by the WTO dispute settlement system or even by WTO negotiators alone. Instead, they would require broader international efforts
