A High Court judge in Belfast has dismissed landmark legal bids to halt the United Kingdom's planned departure from the European Union.
The father of a loyalist paramilitary murder victim and a cross-party group of MLAs mounted separate cases aimed at having the Brexit process declared unlawful.
But Mr Justice Maguire rejected claims by lawyers for Raymond McCord and the Stormont politicians that the British Government cannot use royal prerogative powers to begin EU withdrawal without an Act of Parliament.
Throwing out all grounds of challenge, he said: "The court is not persuaded, for the purpose with which this judicial review is concerned, prerogative power has been chased from the field."
Outside court Mr McCord vowed to take his challenge to the Supreme Court.
With his lawyers due to seek formal permission to appeal at a further hearing next month, he said: "This is not the end of the matter.
"The judge left the door open when he said it could go to a higher court, and more than likely that is going to be the Supreme Court in London."
The campaigner claimed the democratic will of 56% of the Northern Ireland public who voted to remain is being ignored.
"This judgment doesn't mean it's over by any means," he added.
"We are entitled to take this to London and we intend to."
With similar litigation taking place in London, Mr Justice Maguire was only ruling on issues specific to Northern Ireland at this stage.
Prime Minister Theresa May is set to trigger Article 50 of the Lisbon Treaty, the formal process for confirming the UK is to leave, by the end of March 2017.
During a three day hearing at the High Court in Belfast it was contended that the move is illegal without first securing Parliamentary authorisation.
In a 45-page judgment, however, Mr Justice Maguire identified no limits to the use of prerogative power for announcing intentions to quit the EU.
He held that notification in itself does not alter the law of the UK, but only the beginning of a process which will ultimately probably lead to changes.
"On the day after the notice has been given, the law will in fact be the same as it was on the day before it was given," the judge said.
"The rights of individual citizens will not have been changed - though it is, of course, true that in due course the body of EU law as it applies in the UK will, very likely, become the subject of change.
"But at the point when this occurs the process necessarily will be one controlled by parliamentary legislation, as this is the mechanism for changing law in the UK."
Even though the June 23 referendum backed Brexit, a 56% majority of voters in Northern Ireland wanted to remain.
Mr McCord, a victims campaigner whose son Raymond Jr was beaten to death by the UVF in 1997, claimed they have a legal right to resist being forced out.
His lawyers argued that the 1998 Good Friday Agreement has given the Northern Irish public sole sovereignty to decide on their future.
They also predicted Brexit would have a "catastrophic effect" on the peace process, causing constitutional upheaval amid renewed calls for a united Ireland.
Politicians including Alliance MLA David Ford, SDLP leader Colum Eastwood, Sinn Fein Assemblyman John O'Dowd and Steven Agnew of the Green Party also sought to judicially review the British Government's move towards quitting the EU.
The MLAs, whose case is backed by representatives of the voluntary and community sector in Northern Ireland, insisted an Act of Parliament is required before Brexit can take place.
They further contended that the Stormont Assembly should be consulted and asked for its consent.
Counsel for the Assembly members claimed there had been a complete failure on the part of the Northern Ireland Office to undertake any analysis of the impact on devolution.
But a barrister representing the Secretary of State responded by insisting the Government is legally entitled to use the royal prerogative to carry out the people's will to get out of the EU.
He described the power as "common currency" in making and withdrawing from international treaties - pointing out that it was also the method used to join the EU.
Rejecting claims that Parliament is being sidestepped in the process, the barrister said the legislative body will be involved in any law changes resulting from Brexit.
According to his case the 1998 Northern Ireland Act created no substantive legitimate expectation that its people will be consulted on before quitting the EU.
He attempted to rubbish arguments that a withdrawal would damage the Good Friday Agreement by stressing the Government remains committed to the peace process.
Stormont's chief law officer, Attorney General John Larkin QC, also took an opposing stance to the MLAs involved in the litigation.
Looking to a post-Brexit future, he argued that "not one word or phrase in the Belfast Agreement" would be affected.
In his verdict Mr Justice Maguire concluded that it remains to be seen what actual effect the process of change subsequent to notification will produce.
He added: "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 is evident from discussions about, for example, how Northern Ireland's land boundary with Ireland will be affected by actual withdrawal by the UK from the EU."
Welcoming the decision by the High Court this morning, a UK Government spokesperson said: ‘We welcome the Court’s judgment which agrees with us that the Government can proceed to trigger Article 50 as planned.
"As we have always made clear, we stand by our commitments under the Belfast Agreement and the outcome of the EU referendum doesn’t change this.
"We will now await the outcome of the parallel cases under consideration by the England and Wales High Court, before setting out our next steps."