One of the most contentious parts of Theresa May’s defeated Brexit deal hinged on the Irish border backstop -- but what does it mean?
The backstop insurance policy is designed to prevent the reintroduction of border controls between Northern Ireland, part of the U.K., and the Republic of Ireland, an EU member.
Both sides have committed to avoiding the return of a “hard border” -- physical checks or infrastructure -- after Brexit.
Currently, goods and services are traded between the two jurisdictions on the island of Ireland with few restrictions.
The backstop is meant to maintain an open border in the event that the U.K. leaves the EU without securing an all-encompassing deal.
Assurances from EU leaders that the backstop is intended as a temporary measure of last resort completely failed to win over many British skeptics and the EU is adamant that it will not renegotiate the 585-page withdrawal agreement. EU leaders backed a draft version of May’s deal in November last year.
Arlene Foster, who leads Northern Ireland's Democratic Unionist Party, May's parliamentary ally, said her party voted against the deal on Tuesday because of the backstop.
"We want the PM to go back to the EU and say, 'The backstop must go,"' Foster said.
Any separate status for Northern Ireland from the rest of the UK is seen as potentially damaging to the union as a whole.
The EU originally proposed a backstop that would mean Northern Ireland staying in the EU customs union, large parts of the single market and the EU VAT system.
