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.

At first glance, one may think of international investment law as a response to custom (or lack thereof), instead of a field of its application. However, in fact, the opposite is the case. The interpretation and application of customary rules and principles are the bread and butter of international investment law and arbitration. With a diverse range of expert contributors, this collection traces how customary international law is practised in international investment law. It considers how custom should be interpreted and how its rules and principles should be understood and applied by investor-state arbitral tribunals. Raising and addressing vital questions surrounding custom and international law, this collection is a necessary contribution to the scholarship of the theory and history of customary international law and international investment law. This title is also available as Open Access on Cambridge Core.

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.

Fundamentals of Public International Law, by Giovanni Distefano, provides an overview of public international law’s main principles and fundamental institutions.

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.

Provides an in-depth study of the theory, history, practice, and interpretation of customary international law.

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 text explores how the public purpose doctrine reconciles the often conflicting, but equally binding, obligations that states have to engage in regulatory sovereignty while honoring host-state obligations to protect foreign investment. The work examines the multiple permutations and iterations of the public purpose doctrine and concludes that this principle needs to be reconceptualized to meet the imperatives of economic globalization and of a new paradigm of sovereignty that is based on the interdependence, and not independence, of states. It contends that the historical expression of the public purpose doctrine in customary and conventional international law is fraught with fundamental flaws that, if not corrected, will give rise to disparities in the relationship between investors and states, asymmetries with respect to industrialized nations and developing states, and, ultimately, process legitimacy concerns.

International custom is one of the main sources of international law. As a relatively new branch of international law, international investment treaties, emerging in the late 1950s and having been very energetic since the mid-1990s, have become a driving force and an important forum for the formation, application and transformation of the customary international law rules.