THE Good Friday Agreement allows the north an automatic path back into the European Union in the event of a united Ireland, according to SDLP leader Colum Eastwood.
The Foyle MLA said the terms of the 1998 accord mean that a successful unity referendum would see the region rejoin without a lengthy 'Article 49' negotiation.
"That puts us in a unique position on these islands," Mr Eastwood said.
"It is critical that the spirit and the letter of the Good Friday Agreement is written into any future deal between Britain and the EU."
If Scotland votes for independence and wishes to join the EU, then its government will have to apply via a long and complicated process.
But the Good Friday Agreement, as an instrument of international law, specifically states that there can be no external impediment to Northern Ireland becoming a part of "a sovereign united Ireland".
The SDLP also points to the precedent of German reunification in 1990.
After East Germany was united with West, the new entity was considered a single member state – the same would be argued for a united Ireland.