Chapter 5 analyses the three challenges facing international tribunals considered in this book in investment treaty arbitration. Regarding the challenge of managing change, investment treaty arbitration displays similarities and differences with the inter-State tribunals studied. Using the example of the minimum standard of treatment, the chapter shows that like the inter-State tribunals studied, investment treaty tribunals contribute to broader processes of change in international legal norms. Yet differently from the other tribunals studied, investment treaty arbitration has an overriding focus on determining the permissible degree of change in host State regulation. In relation to scrutinising State conduct for compliance with international law, investment treaty arbitration raises comparable questions to the other international tribunals studied regarding the appropriate intensity of review and the methods of review used by adjudicators. Finally, the chapter considers why, unlike the inter-State tribunals studied, investment treaty tribunals rarely adjudicate in a facilitative, forward-looking manner that aims to complement post-adjudication cooperation between the parties.

Chapter 6 draws together and extends the comparative analysis that has unfolded across the prior chapters. It explains why tribunals’ practices differ across the regimes studied, focusing on contextual differences between the selected tribunals. It also assesses to what extent the practices of the selected tribunals provide insights into wider problems facing international adjudication and legal techniques that are potentially transferable across contexts. Structurally, the chapter discusses consecutively my findings in relation to the three challenges confronting international tribunals analysed throughout the book: managing changes in international law or relevant facts, calibrating the appropriate standard and method of review when scrutinising State conduct for compliance with international law, and contributing to broader processes of dispute resolution. The chapter finishes with some final remarks that close the book, concerning its contribution to our understanding of the role of international adjudication in contemporary international law and its implications for future studies in this field.

Chapter 2 analyses the three selected challenges facing international tribunals – managing change, reviewing State conduct for compliance with international law, and dispute resolution – in World Trade Organization (WTO) adjudication, focusing on environmental disputes. WTO tribunals have often been faced with potential changes in international legal norms or changes in relevant facts. The chapter analyses the approach to the standard of review developed under the Agreement on the Application of Sanitary and Phytosanitary Measures. While this approach avoids WTO adjudicators determining questions of scientific correctness, it requires them to decide what counts as an adequate risk assessment process. The chapter then analyses the necessity tests developed by WTO adjudicators for scrutinising measures that pursue a permissible regulatory aim but also restrict a treaty-protected interest in trade liberalisation. Finally, the chapter interrogates an aspect of the WTO’s ‘chapeau jurisprudence’ that many commentators have read as a desirable example of international tribunals engaging in a procedural form of scrutiny and pushing regulating States to consider affected foreign interests.