Britain's departure from the EU faced two separate legal challenges in Northern Ireland's High Court Friday.
Lawyers for one group lodged an application with the court to challenge London's decision to abide by the June 23 referendum result and proceed to leave the European Union.
In a letter last month, the group had asked British Prime Minister Theresa May to allow votes on the issue in both the British parliament and in the Northern Ireland Assembly before triggering the formal process to leave.
The politicians and activists bringing the action want May's government to consider the potential impact on Northern Ireland's peace process before triggering the formal process to leave the EU.
Jones Cassidy Brett, the legal firm representing the group, said: "The various assurances sought by our clients have not been forthcoming and, indeed, the response heightened their concerns about the approach the government was likely to take."
This legal action was initiated only hours after it emerged that the court had agreed to fast-track a separate challenge by a victims' rights campaigner, who argues that Brexit would contravene international agreements underpinning peace in Northern Ireland.
That case taken by Raymond McCord, 62, will be heard on September 5, the first official day the court is due to sit following the summer recess.
His legal team says the promptness of the hearing, and a decision this week to grant public funding to underwrite it, confirm its importance.
McCord believes Brexit would contravene the 1998 Good Friday Agreement, which effectively brought an end to the three decades of armed conflict in Northern Ireland.
"I am very concerned about the profoundly damaging effect that a unilateral withdrawal of the UK from the EU will have upon the ongoing relative stability in Northern Ireland," he says in his affidavit to the court.
McCord believes the loss of EU funding towards conflict resolution projects in Northern Ireland could jeopardise the ongoing peace process if not replaced.
His legal costs will be met from public funds, which his lawyer, Ciaran O'Hare of McIvor Farrell Solicitors, said were granted "only in cases of merit, complexity and public importance".
Northern Ireland has its own legal jurisdiction within the United Kingdom, as does England and Wales, and Scotland.
The British government already faces a legal challenge to stop it beginning the process of leaving the EU without an act of parliament.
In the English courts, lawyers at Mishcon de Reya argue that the British government cannot trigger Article 50, the legal process for leaving the bloc, without a parliamentary debate and vote authorising it to do so.