The Advocate General of the European Court of Justice (ECJ) has declared that plans to form a European Patents Court are incompatible with EU treaties, marking a setback in the long-running campaign to create a centralised patent litigation system in Europe.

The Council of the European Union requested the opinion of the ECJ last June, with the Advocate General's response on 2 July stating that: "As it stands at present, the envisaged agreement creating a unified patent litigation system is incompatible with the treaties."

The proposed system, recently renamed the European and European Union Patents Court, was put forward in an effort to centralise the patent litigation system under one court in Europe and cut down on jurisdictional issues.

Bristows intellectual property partner Alan Johnson said: "This issue has been under negotiation for an absolute eternity. Most of the industry would like to see a centralised European approach so it is not necessary to litigate in multiple jurisdictions.

"The Advocate General's opinion is very disappointing when so much effort has gone into this. If the court agrees, it will be difficult to see how it will be workable from here and might be the death knell of the dossier."

The question of language has raised concerns in some quarters, in particular from native Spanish speakers, as the proposal includes the requirement for the court to conduct litigation in English, French and German.

The Advocate General's opinion is non-binding and will be considered by the ECJ later this year.