The president of the High Court will next month consider arguments concerning whether the Irish courts have any jurisdiction to deal with a challenge aimed at halting Brexit.

A British barrister and a number of Green Party politicians in Britain and Northern Ireland have brought proceedings seeking to establish if Britain can halt Brexit after triggering Article 50 of the Lisbon Treaty.

They are asking the High Court to refer issues in the case for determination by the Court of Justice of the EU (CJEU). They want various declarations or interpretations of the treaties of the EU, including a declaration that Article 50, once triggered, can be unilaterally revoked by the UK government.

Ireland and the Attorney General have entered a conditional and without prejudice appearance before the High Court to contest the action and they want the issue of jurisdiction to be decided first.

When setting May 31st as the date to deal with making directions for resolution of various issues related to jurisdiction, Mr Justice Peter Kelly said that if the State succeeds in what it described as its “knockout blow” to the challenge, that would be the end of the matter.

If not, then a further hearing will be required.

Maurice Collins SC, for the State parties, said both sides had agreed the matter should be expedited and a timetable for the exchange of documents in advance of the directions hearing had been drawn up.

Power

Among the issues to be considered as part of the hearing is a claim the Irish courts have power to consider the matter under the “Recast Brussels Regulation” which governs jurisdiction, recognition and enforcement of judgments in civil and commercial matters across the EU.

Mr Collins said it was the State’s case this Brexit case was “plainly not” a commercial or civil matter.

The more fundamental question was whether the High Court had any power to grant the relief sought against the State defendants, he said.

Other issues include whether British citizens who come to Ireland retain their EU rights notwithstanding their country’s withdrawal and how they are affected by the Lisbon Treaty or by reference to such matters as the Good Friday Agreement or the Common Travel Area.

The question of jurisdiction runs very close to the question of whether such questions are justiciable at all, counsel said.

Mr Collins also said there was the question as to why this case was brought here. The plaintiffs were British Queens Counsel Jolyon Maugham, Northern Ireland Green Party leader and MLA, Steven Agnew, Jonathan Bartley, co-leader of the Green Party of England and Wales, and Green Party MEP for the south-east of England, Keith Taylor.

The issues as outlined should be determined in the manner agreed rather than by seeking to isolate a single issue or apply for a dismissal, Mr Collins said.

Martin Hayden SC, for the plaintiffs, said his side will raise no issue or seek any advantage in relation to the conditional appearance of the State. His side wanted the matter expedited and agreed to the timetable.

After Mr Justice Kelly said he did not propose to give any directions in relation to the question of putting the UK government on notice of these proceedings and that was a matter for the plaintiffs themselves, Mr Hayden said that was not a matter which would arise between now and the hearing date.