Future of the Investor-State Dispute Settlement Mechanism in the European Union After the "Achmea" Decision and "Opinion 1/17"

This paper aims to discuss two important decisions of the Court of Justice of the European Union, "Achmea" and "Opinion 1/17", regarding European Union international investment law and to evaluate their effect on the developments and changes in international investment law, especially for investor-state dispute settlement mechanisms. The "Achmea" decision, where the Court found the provisions in Intra-EU BITS regarding investor-state dispute resolution provisions to be in conflict with European Union law, launched a discussion on the applicability of the investor-state dispute settlement provisions in the Energy Charter Treaty. By ending investor-state arbitration among European Union members, the Achmea decision made the Investment Court System discussed in "Opinion 1/17" and the analysis of that decision more important. This paper, with the analysis of these two important Court decisions, aims to discuss these topics. At the same time, other developments in this area are taken into consideration, such as the modernization efforts under the Energy Charter Treaty, reform under the United Nations Commission on International Trade Law (UNCITRAL) Working Group III, other relevant Court of Justice decisions or arbitral awards, and regulations within the European Union, with the goal of shedding light on the developments in this area.