The steadily rising number of investor-State arbitration proceedings within the EU has triggered an extensive backlash and an increased questioning of the international investment law regime by different Member States as well as the EU Commission. This has resulted in the EU’s assertion of control over the intra-EU investment regime by promoting the termination of bilateral intra-EU investment treaties (intra-EU BITs) and by opposing the jurisdiction of arbitral tribunals in intra-EU investor-State arbitration proceedings. Against the backdrop of the landmark decision of the European Court of Justice, the book offers an in-depth analysis of the interplay of international investment law and the law of the European Union with regard to intra-EU investments, i.e. investments undertaken by an investor from one EU Member State within the territory of another EU Member State.