Article 31(3)(c) of the Vienna Convention on the Law of Treaties and the principle of systemic integration in international investment law and arbitration

The treatise gives scholars and practitioners useful guidance for resolving the key issues of contemporary investment law (i. e. how best to balance investor’s rights to investment protection and host states’ rights to regulate) by applying Article 31(3)(c) VCLT and the so-called ‘Principle of Systemic Integration’. It illustrates the potential and limits of harmonious treaty interpretation. For this purpose, it demonstrates the relevance of extraneous rules in the system of international investment law and arbitration, deals extensively with the interpretation of Article 31(3)(c) VCLT, and explains in depth the ‘principle of systemic integration’. The author critically analysis – at the example of the FET standard, the prohibition of unlawful expropriation and the various non-discrimination provisions in investment treaties – how investment tribunals and international courts have interpreted investment treaties in the light of extraneous rules of international law.