The European Court of Justice has ruled that Ireland breached EU law by taking Britain before a United Nations tribunal in relation to the Sellafield nuclear plant.
The Irish Government took an action under the UN Convention on the Law of the Sea in 2001 in an effort to have the controversial facility shut down.
The body later issued recommendations to resolve the dispute, but the European Commission took Ireland to court, claiming it had breached EU law by turning to an outside body.
The Court of Justice upheld this stance today, saying Ireland should settle the dispute with Britain within the framework of the EU.