Patrick Dumberry provides a comprehensive analysis of the rules of customary international law in the field of international investment law.

Transnational investment involves a variety of actors (States, public and private legal entities, and natural persons) whose relationships are governed by rules and legal instruments belonging to different legal systems. This book provides a systematic study of the sources of rights and obligations in the field of transnational investment, and their coordination and interaction. It focuses primarily on the network of over 3,000 Bilateral Investment Treaties, international investment contracts, customary international law, the main multilateral treaties, national legislation, international case law and general principles of law. The book, firmly based on State practice, arbitral awards and national decisions, is indispensable to fully appraise the nature and content of the claims of private investors as well as to identify the law applicable in investment arbitration.

Although customary international law has long been an important source of rights and obligations in international relations, there has been extensive debate in recent years about whether this body of law is equipped to address complex modern problems such as climate change, international terrorism, and global financial instability. In addition, there is growing uncertainty about how, precisely, international and domestic courts should identify rules of customary international law. Custom's Future seeks to address this uncertainty by providing a better understanding of how customary international law has developed over time, the way in which it is applied in practice, and the challenges that it faces going forward. Reflecting an interdisciplinary mix of historical, empirical, economic, philosophical, and doctrinal analysis, and containing chapters by leading international law experts, it will be of use to lawyers, judges, and researchers alike.

The fair and equitable treatment (‘FET’) standard is a type of protection found in BITs which has become in the last decades one of the most controversial provisions examined by arbitral tribunals. This book first examines the interaction between the ‘minimum standard of treatment’ (MST) and the FET standard and the question why States started referring to the former in their BITs. It also addresses the question whether the FET should be considered as an autonomous standard of protection under BITs. This book also examines the controversial proposition that the FET standard should now be considered as a rule of customary international law. I will show that while the practice of States to include FET clauses in their BITs can be considered as general, widespread and representative, it remains that it is not uniform and consistent enough for the standard to have crystallised into a customary rule. States also lack the necessary opinio juris when including the clause in their BITs.

This book analyzes the tension between the host state’s commitment to provide regulatory stability for foreign investors – which is a tool for attracting FDI and generating economic growth – and its evolving non-economic commitments towards its citizens with regard to environmental protection and social welfare. The main thesis is that the ‘stabilization clause/regulatory power antinomy,’ as it appears in many cases, contradicts the content and rationale of sustainable development, a concept that is increasingly prevalent in national and international law and which aims at the integration and balancing of economic, environmental, and social development. To reconcile this antinomy at the decision-making and dispute settlement levels, the book employs a ‘constructive sustainable development approach,’ which is based on the integration and reconciliation imperatives of the concept of sustainable development as well as on the application of principles of law such as non-discrimination, public purpose, due process, proportionality, and more generally, good governance and rule of law. It subsequently re-conceptualizes stabilization clauses in terms of their design (ex-ante) and interpretation (ex-post), yielding stability to the benefit of foreign investors, while also mitigating their negative effects on the host state’s power to regulate.

Fundamentals of Public International Law, by Giovanni Distefano, provides an overview of public international law’s main principles and fundamental institutions. By introducing the foundations of the legal reasoning underlying public international law, the extensive volume offers essential tools for any international lawyer, regardless of the specific field of specialization. Dealing expansively with subjects, sources and guarantees of international law, university students, scholars and practitioners alike will benefit from the book’s treatment of what has been called the “Institutes” of public international law.

Rules of customary international law provide basic legal protections to foreign investors doing business abroad. These rules remain of fundamental importance today despite the growing number of investment treaties containing substantive investment protection. In this book, Patrick Dumberry provides a comprehensive analysis of the phenomenon of custom in the field of international investment law. He analyses two fundamental questions: how customary rules are created in this field and how they can be identified. The book examines the types of manifestation of state practice which should be considered as relevant evidence for the formation of customary rules, and to what extent they are different from those existing under general international law. The book also analyses the concept of states' opinio juris in investment arbitration. Offering guidance to actors called upon to apply customary rules in concrete cases, this book will be of significant importance to those involved in investment arbitration.