The course provides a comprehensive overview of Investment Arbitration, a key and increasingly debated mechanism for resolving disputes between foreign investors and host states. We will explore how investment arbitration, while using commercial arbitration techniques, uniquely operates within investment treaties and contracts. A core focus will be interpreting substantive standards—like Fair and Equitable Treatment and expropriation—to protect investors without undermining the host state's right to regulate its economy. The course also critically examines the intricate relationship between investment arbitration and European Union Law. By exploring these tensions and developments, the course aims to equip students with the ability to critically analyse investment arbitration and engage thoughtfully with upcoming trends in its reform.