The Supreme Court has ruled that the devolved UK regions do not need to have a say in the process leading up to Brexit.
It means that Prime Minister Theresa May won’t have to consult the Northern Ireland Assembly, Scottish Parliament and Welsh Assembly before triggering Article 50.
The ruling was made on Tuesday as the Government lost its historic legal challenge over Brexit.
Judges decided by a majority of eight to three that the Government must get Parliament’s approval in order to formally begin the Brexit process, rejecting an appeal by ministers.
Ms May had said she plans to trigger Article 50 by the end of March, following last year’s vote in favour of the UK leaving the European Union.
While losing the challenge will come as a blow, the decision over the devolved powers could have been much more significant in upsetting her timetable if it had gone the other way.
It is expected to happen before the Government's deadline of 31 March.
Giving his reaction, TUV leader Jim Allister said: "I greatly welcome the firm rejection by the Supreme Court of the nonsense idea that the devolved assemblies required to be consulted - even afforded a veto, some argued - before the United Kingdom could implement the sovereign decision of its people to leave the EU.
"In holding firm to the central sovereignty of the UK this is a good decision for the unity of the United Kingdom."
Ulster Unionist MPs Tom Elliott and Danny Kinahan said "it is welcome that clarity has finally been given on this issue".
They went on: "The challenge now is to secure the best deal for Northern Ireland."
SDLP Leader Colum Eastwood MLA said:"This judgement marks a significant and serious departure from our devolution settlement.
"It significantly undermines the value placed on the democratic mandate of our Assembly. Northern Ireland voted to remain in the European Union, yet the Northern Ireland Assembly is being denied any role or rights in the upcoming negotiations with the European Union."