Ireland's National Trust has been given the go-ahead to challenge a decision giving permission for a new nuclear power station on t he west coast of England.
The judicial review will be heard by three judges in the UK Court of Appeal over two days before the end of July, if possible.
An Taisce, the National Trust for Ireland, is challenging the legality of the March 2013 decision by the UK Secretary of State for Energy and Climate Change to grant development consent for the project at Hinkley Point in Somerset - around 150 miles (241km) from Ireland.
Its lawyers say there was a failure to undertake ''transboundary consultation'' with the Irish people beforehand as required by the European Commission's Environmental Impact Assessment Directive.
The UK Government says that such consultation was not necessary as it had already dealt with the potentially very severe impact which nuclear accidents - although agreed to be unlikely - could have, were they to happen.
Transboundary consultation was only required in relation to significant environmental effects of which there was a "real risk" or a "serious possibility", it argued, and not those in relation to which there was only a bare possibility.
In December, a UK High Court judge dismissed An Taisce's argument that the UK Secret ary of State misdirected himself as to the meaning of the relevant regulations in considering only impacts arising from the ordinary regulated operation of the nuclear power station and not ''unlikely'', but nevertheless possible, impacts from other scenarios.
She also rejected its claim that there was a failure to comply with the regulations by omitting to take into account the possible impacts arising from unplanned or accidental effects of the development.
She said that opinions from a variety of expert sources provided a sound and reason ed rational basis for the UK Secretary of State to come to his decision and he had sufficient information to amount to a comprehensive assessment for the purposes of the Directive.
Today, Lord Justice Sullivan said that An Taisce had an arguable point and, while he did not venture that it had a real prospect of success, it was desirable that the court should give a definitive view as to whether there should be a reference to the Court of Justice of the European Union (CJEU) and, if not, on the meaning of the Directive.