EU Law and Investor-State Dispute Settlement: Facing Complementarity

The chapter reviews the relationship between EU law and international investment law and their respective systems of adjudication, that is, the Court of Justice of the European Union (CJEU) and investment arbitration. It argues that the mindset adjudicators adopt in approaching this relationship should change from a paradigm of (potentially destructive) conflict towards one of (mutually beneficial) complementarity. The paradigm shift the chapter advocates entails two distinct steps: first, realizing that EU law and international investment law have common goals, namely creating legal structures for international investment relations that reflect core constitutional values, including democracy, rule of law, human rights, and sustainable development; and second, aligning the relationship of the CJEU and investment tribunals according to the triad of mutual respect, mutual support, and mutual control, similar to how the relations between the constitutional courts of Member States and the CJEU have developed over time.