One of the most prominent and urgent problems in international governance is how the different branches and norms of international law interact and what to do in the event of conflict. With no single 'international legislator' and a multitude of states, international organisations and tribunals making and enforcing the law, the international legal system is decentralised. This leads to a wide variety of international norms, ranging from customary international law and general principles of law, to multilateral and bilateral treaties on trade, the environment, human rights, the law of the sea, etc. Pauwelyn provides a framework on how these different norms interact, focusing on the relationship between the law of the World Trade Organisation (WTO) and other rules of international law. He also examines the hierarchy of norms within the WTO treaty. His recurring theme is how to marry trade and non-trade rules, or economic and non-economic objectives at the international level.

In The Right to Food and the World Trade Organization’s Rules on Agriculture: Conflicting, Compatible, or Complementary?, Rhonda Ferguson explores the relationship between the human right to food and agricultural trade rules. She questions whether States can adhere to their obligations under both regimes simultaneously. These two regimes are frequently portrayed to be in tension with one another. The content and contours of the right to food under international human rights law and WTO rules on domestic supports, export subsidies, and market access are considered through the lens of norm conflict theories. The analysis is situated within the context of the debate surrounding the fragmentation of international law.

Recent decades have witnessed an impressive process of normative development in international law. Numerous new treaties have been concluded, at global and regional levels, establishing far-reaching international legal and regulatory regimes in important areas such as human rights, international trade, environmental protection, criminal law, intellectual property, and more. New political and judicial institutions have been established to develop, apply and adjudicate these rules. This trend has been accompanied by the growing consolidation of treaty norms into international custom, and increased references to international law in domestic settings. As a result of these developments, international relations have now reached an unprecedented level of normative density and intensity, but they have also given rise to the phenomenon of 'fragmentation'. The debate over the fragmentation of international law has largely focused on conflicts: conflicts of norms and conflicts of authority. However, the same developments that have given rise to greater conflict and contradiction in international law, have also produced a growing amount of normative equivalence between rules in different fields of international law. New treaty rules often echo existing international customary norms. Regional arrangements reinforce undertakings that already exist at the global level; and common concerns and solutions appear in many international legal fields. This book focuses on such instances of normative parallelism, developing the concept of 'multisourced equivalent norms' in international law, with contributions by leading international law experts exploring the legal and political implications of the concept in a variety of contexts that span the full spectrum of international legal norms and institutions. By concentrating on situations governed by a multitude of similar norms, the book emphasizes the importance of legal contexts and institutional settings to international law-interpretation and application.

Peremptory Norms of General International Law (Jus Cogens): Disquisitions and Dispositions is a collection of contributions on various aspects of jus cogens in international law.

Beyond Human Rights, previously published in German and now available in English, is a historical and doctrinal study about the legal status of individuals in international law.

A richly textured account of the making, implementing, and changing of international legal regimes, which encompasses law, politics and economics.

The Nature of International Law provides a comprehensive analytical account of international law within the prototype theory of concepts.