Disputes between Members States of the European Union and Jurisdiction of the Court of Justice of the European Union

The article aims at resolving the issue whether the Court of Justice of the European Union (CJEU) has an exclusive jurisdiction under Article 344 of the Treaty on Functioning of the European Union (TFEU) to resolve disputes between Member States, stemming from provisions of an international treaty, a party to which is the EU. This problem is especially relevant in cases when a mixed international agreement envisages independent institutions of dispute resolution. The position of the CJEU is expressed in the case of Mox Plant. The European Commission applied to the CJEU against Ireland, because it considered that Ireland, which started an arbitration procedure against United Kingdom under the UN Convention on the Law of the Sea, has infringed the exclusive jurisdiction of the CJEU under Article 344 of the TFEU. The EU is also a Contracting Party to the UN Convention on the Law of the Sea. Therefore according to the consistence case practice of the Court, the provisions of the Convention that fall under the competence of the Union constitute an indivisible part of the EU legal system. Only in such case when a provision of a treaty is attributed to exclusive competence of the Member States, the jurisdiction of the CJEU regarding that provision can be negated. Thus, when deciding on the issue of exclusive jurisdiction of the CJEU in principle, a problem of attribution of the EU and Member States’ competences arises