The European Commission's plans to create a unified patent litigation system were dealt a heavy blow today when the 27-member trading bloc's senior court ruled the idea unlawful.

The ruling comes with the Commission just days away from concluding a decades-long effort to reform its bureaucratic patent system. Currently, a business that wants to protect its intellectual property in Europe needs to apply for a patent in every member state; the Commission has proposed a single patent system with a central court to hear disputes.

The Commission was hoping to agree to a deal on Thursday that would allow 25 of its members to implement the scheme, leaving out Italy and Spain, which have refused to join the new system because it doesn't recognize their national languages.

But the Court of Justice of the European Union has now ruled that the plan is unlawful because it would create a new patent court and thereby undermine its own authority as Europe's final court of appeal.

The Commission insisted that its plan would still work because the European Patent Court—which has been ruled unlawful—is only part of the idea.

But Will Cook, partner at Marks & Clerk Solicitors, said the court's ruling was “a huge step in the wrong direction for those frustrated by the existing diverse, complicated, and varyingly expensive national systems.”

Cook said that even if the Commission decided to implement the scheme regardless, it was now unlikely to work because litigants would be uncertain about whether the Court of Justice would let the patent court's rulings stand.

“For the unitary court to work, there must be confidence that any final court of appeal will implement clearly and consistently the technical and specialized patent law covering the jurisdictions in question,” said Cook. “Users of the patent system are likely to stay with the current system of national enforcement.”