How does international law protect a European, U.S. or Chinese firm investing abroad, and when can foreign investors seek compensation from host governments in international arbitration? How could treaties be designed to help countries attract foreign investment to build up their infrastructure, exploit natural resources or transit to a 'green economy', without endangering their regulatory autonomy or granting too much power to foreign multinationals? This course examines the public international law on the entry and protection of foreign investment both in customary international law and treaties, in particular under bilateral investment treaties (BITs), free trade agreements (FTAs including NAFTA/USMCA, CETA and CPTPP) and the Energy Charter Treaty. It provides an overview of procedures for investor-state dispute settlement (ISDS) under arbitral facilities such as ICSID and elaborates on core substantive principles of foreign investment access and protection through an analysis of treaty provisions and the exponentially growing case law in the field. The course also devotes attention to the critiques of the ISDS system and ongoing treaty reform efforts, as well as the environmental and social issues surrounding foreign investment and sustainable development, and efforts to regulate the conduct and due diligence of multinational corporations. This is an overview course on the subject matter. No prior knowledge is required. Students in disciplines other than law are welcome.