The EU could use an obscure provision in an international trade treaty to preserve a frictionless border in Ireland in the aftermath of a no-deal, no-transition Brexit, a new report commissioned by MEPs suggests.

The report to the European Parliament Constitutional Affairs Committee on the legal institutional implications of a hard Brexit - a prospect which is unlikely in the current state of negotiations, he suggests - has been prepared by Dublin City University's energetic Prof Federico Fabbrini, director of its Brexit Institute, and will be presented at a meeting of the committee on Thursday.

It warns that in the event of a hard, no-deal Brexit in which there was no transition arrangement or withdrawal agreement, from April 1st, 2019, "contingency plans would need to be put in place from the EU side to deal with the sudden emergence of a customs border between Ireland and Northern Ireland".  

That could be done, he argues, by invoking Article XXIV(3) of the General Agreement on Tariffs and Trade (GATT) , which provides for a so-called "frontier traffic exception". It is one way of doing what four parties in the North have urged in recent days - keeping the North inside the customs union and single market.  

The clause, which has never been used before, allows that custom provisions under the World Trade Organisation regime which would prevail in both the EU and UK in the event of a no-deal Brexit "shall not be construed to prevent: a) advantages accorded by any contracting party to adjacent countries in order to facilitate frontier traffic . . ."

This would allow the EU, Fabbrini says, to "declare the entire territory of Northern Ireland to be a frontier zone to the EU customs union; thereby removing the need for customs controls (at least on the EU side)".