A ruling by the High Court in London that Brexit cannot be triggered by uise of Royal Perogative has been welcomed.
The pound strengthened on the back of the decision this morning.
This now effectively means that a debate and vote by MPs on Brexit must take place.
It also means Prime Minister Theresa May does not have permission to pull the trigger on Article 50 of the Lisbon Treaty - the formal mechanism by which Britain signals its departure from the European Union, until Parliament gives its consent.
Foyle SDLP MP Mark Durkan said: “I welcome this important ruling by the High Court.
“I have consistently called on the government not to begin the formal process of triggering Article 50 on withdrawal from the EU until its proposals have been fully debated in the House of Commons and voted upon by MPs.
“Parliament has the right and the duty to ensure that we best consider how these matters are dealt with. However, the idea seemed to be that Parliament had no role whatsoever, and could entrust these matters entirely to the royal prerogative and those who are meant to be leading the process. That would constitute a request for us to commit a dereliction of duty.”
The SDLP, Mr Durkan said, has been consistent in its objection to the use and abuse of the royal prerogative.
“Those of us who believe in parliamentary democracy know that major decisions where substantive details and strategic options count, should be debated and voted upon by MPs, rather than being pocketed as a personal tactic for a Prime Minister,” he added.