As a subject of public international law, the European Union (EU) concludes international agreements with other subjects of international law, i.e. international organisations and states. The EU may enter into such treaties on its own, or jointly with its Member States – depending on the area of competence (exclusive EU competence or shared competences) to which the treaty in question applies.
The European Court of Justice (ECJ) enjoys specific competences with regard to the conclusion, interpretation and application of international treaties to which the EU is a party. The ECJ can verify the compatibility of an international agreement with the EU Treaties either ex ante or ex post. Furthermore, international treaties concluded by the EU are considered as acts of the institutions and may be subject to interpretation by the Court, especially in the preliminary reference procedure.
As a rule no ECJ jurisdiction is envisaged in EU free trade agreements (FTAs), as dispute settlement is carried out through a joint committee, followed by arbitration. In certain specific cases, such as in the European Economic Area and the EU-Turkey Customs Union, the ECJ may have direct involvement in the enforcement of the agreement.
The EU-UK Withdrawal Agreement and the EU-UK Trade and Cooperation Agreement (TCA), however, diverge on dispute settlement rules and the role of the ECJ. In the former, the ECJ maintained its jurisdiction during, as well as beyond, the transition period with regard to specific chapters; the ECJ also has the final word on interpreting EU law applied in virtue of the agreement. Conversely, the TCA includes a role for the Court only in regard to the United Kingdom’s participation in EU programmes, and its dispute settlement rules vary throughout the agreement.
Source: Briefing – European Court of Justice and international agreements – 15-07-2021