Northern Ireland's High Court has ruled the law of the province does not restrict the British prime minister's ability to trigger an exit from the European Union, and the consent of the regional parliament is not required.
But it said it would defer to English courts on the wider issue of whether Theresa May and her ministers have the authority to invoke Article 50 of the EU Lisbon Treaty, the mechanism by which a nation can leave the bloc, without the explicit backing of the British parliament.
A cross-party group of politicians had claimed the country should have a veto on an exit and said the Stormont Assembly should have a say on whether to trigger negotiations with Europe.
Justice Paul Maguire said: "While the wind of change may be about to blow, the precise direction in which it will blow cannot yet be determined so there is a level of uncertainty, as evidenced by the discussion about how the Northern Ireland land border with Ireland was affected by withdrawal from the EU."
Raymond McCord, whose son was murdered by loyalist paramilitaries, had a separate Brexit challenge surrounding its impact on the peace process heard alongside that of the politicians at the High Court in Belfast.
"Today is a setback but we will see the judges in London," Mr McCord told journalists at the court.
"I believe what we are doing is correct. Fifty-six percent of the people of this country (Northern Ireland) voted to remain."
A group of politicians and rights groups who took a parallel case that was merged with McCord's said they were "deeply disappointed" by the rejection of their case, but had not yet decided whether to appeal.
