Explainer: What is the 'backstop'?
The backstop has remained a major sticking point in Brexit talks, but what exactly does it mean?
Here's everything you need to know:
The 500 kilometre stretch from Dundalk to Derry becomes the only de facto land frontier between the EU and the UK jurisdictions after Brexit.
The border-free EU single market ended customs controls in January 1993. Ceasefires leading to the 1998 Good Friday Agreement ended security checks.
Brexit risks of a return of customs controls which could be a focus for violent attacks. The UK was originally determined to leave both the EU customs union and the single market. That would mean trade tariffs and product standard checks – otherwise called “a hard border.”
Brussels, London and Dublin agreed they did not want a “hard border.” In December 2017, they agreed a formula now called “the backstop.” In practice the North stays in the customs union with no tariffs. The North would also mimick EU single market product standards minimising checks.
The Democratic Unionist Party, propping the minority UK government, objected to the North getting different Brexit terms. The arrangement was extended to all the UK as a temporary insurance policy expiring when a long-term EU-UK trade deal is done.
Radical Brexiteers and pro-EU politicians objected fearing it would leave the UK in real terms trapped inside the EU if they could not finalise a trade deal. The EU has given assurances that this will not happen – but refused to fix a backstop end-date.