The Court of Justice of the European Communities has determined that a draft agreement which would create a European and Community Patents Court is not compatible with existing treaties. Opinion 1/09 of the Court, March 8, 2011. According to the court, the draft agreement would give this international patent court exclusive jurisdiction, thus supplanting national courts and tribunals, and would allow the patent court to become the sole court to interpret and apply European Union law. The court issued the opinion at the request of the Council of the European Union.

The court was particularly concerned that the agreement “by conferring on an international court[,] which is outside the institutional and judicial framework of the European Union[,] an exclusive jurisdiction to hear a significant number of actions brought by individuals in the field of the Community patent and to interpret and apply European Union law in that field, would deprive courts of Member States of their powers in relation to the interpretation and application of European Union law and the Court of its powers to reply, by preliminary ruling, to questions referred by those courts and, consequently, would alter the essential character of the powers which the Treaties confer on the institutions of the European Union and on the Member States and which are indispensable to the preservation of the very nature of European Union law.”