The European Patent Office (EPO) administers patents that can apply in more than one country. Patents only apply in the countries chosen, though, and applicants must have the patent claims translated into that country's language for them to apply.
EU governing bodies have worked for many years on plans to unify the EU's patent system. The European Patent Court was designed to rule on disputes related to EPO-issued patents through a single courts system. The EPO system works for the EU's 27 countries and for other countries that have signed up to the scheme.
Before the agreement was signed, though, the governing bodies asked the ECJ to give its opinion on whether it would be legal in order to avoid signing an agreement that would subsequently be declared to be in conflict with EU law.
The ECJ has said that the Court would be incompatible with EU law because it would interpret EU law without being an official EU body.
The proposed European and Community Patent Court would exist outside of the judicial structures already in place and so would leave citizens potentially without recourse to action though existing EU courts, the ECJ said in its opinion. That could deprive people of access to justice, it said.
"The envisaged 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," said an ECJ statement outlining the contents of the opinion.
"The agreement would also affect the powers of the Court to reply, by preliminary ruling, to questions referred by those national courts. Accordingly, the agreement would alter the essential character of the powers conferred on the institutions of the European Union and on the Member States which are indispensable to the preservation of the very nature of European Union law," the statement said.
The European Commission has said that the opinion will not affect the progress of an alternative plan that has emerged in recent months of a cut-down version of the pan-EU patents system.
This plan is heavily reliant on English, French and German and does not require all documents to be translated into the language of every country in which the patent is valid. It was initiated by 12 countries, and all but two of the EU's 27 countries have since said they will join it.
The plan has already been backed by the European Parliament and is due to be approved by the Competitiveness Council of EU Ministers on Thursday. The European Commission will then draw up specific plans which must be approved by the European Parliament and the Council of Ministers.
"The opinion should have no impact on the decision foreseen to be taken by Member States on 10 March at the Competitiveness Council following the consent of the European Parliament authorising a move to enhanced cooperation in the area of unitary patent protection," said a European Commission statement. "The creation of unitary patent protection is legally distinct from the creation of the European Patent Court. It is important to maintain the momentum to bring decades of discussion on the EU patent to a quick and successful solution through enhanced cooperation."
The ECJ said that the European Patent Court as proposed in 2009 was not compatible with EU law because it broke the chain of accountability running from countries to EU courts.
"A State is obliged to make good damage caused to individuals as a result of breaches of European Union law for which it is responsible, irrespective of which authority of that State, including a judicial authority, caused the breach," said the ECJ statement. "Likewise, where an infringement of European Union law is committed by a national court, a case may be brought before the Court to obtain a declaration that the Member State concerned has failed to fulfil its obligations."
"if a decision of the European and Community Patent Court were to be in breach of European Union law it could not be the subject of infringement proceedings nor could it give rise to any financial liability on the part of one or more Member States," it said.