Proportionality, Reasonableness and Standards of Review in International Investment Law and Arbitration

International investment law is one of the most dynamic fields of international law, and yet it has been criticised for failing to strike a fair balance between private and public interests. In this valuable contribution to the current debate, Valentina Vadi examines the merits and pitfalls of arbitral tribunals’ use of the concepts of proportionality and reasonableness to review the compatibility of a state’s regulatory actions with its obligations under international investment law.