For some time, the European Union and International Arbitration legal orders enjoyed a peaceful coexistence, each operating in its own sphere and according to its own "first principles." That has radically changed over the last decade or so. The difficulties began with the so-called intra-EU bilateral investment treaties which the EU came to view as interfering with the "autonomy" of EU law, as defined by the EU. Although the intra-EU BITS are on the road to dissolution, there remain related issues under both the Energy Charter Treaty and the ICSID Convention. More generally, the notion of "EU public policy" has grown to the point that it now is challenging international arbitration, both commercial and investment. Other areas of conflict, such as the compatibility with EU law of judicial and arbitral "anti-suit" injunctions, ahve arisen. Finally, the EU is playing a leading role in the reform of the international investment law and arbitration architecture, championing in particular the creation of a"multilateral investment court," a proposal that many countries around the world disfavor. With the Lisbon Treaty, amending the governing treaties of the EU, the EU has acquired exclusive competence, vis-a-vis the Member States over the field of investor protection, and a whole new generation of international investment agreements, starting with the CETA Agreement with Canada, is entering into force. These treaties clearly reflect the EU's vision of what the investment law and arbitration picture should look like going forward. The course covers all these aspects -- and others -- of the European Union/international arbitration interface.