What is the Brexit backstop?

Once more commonly heard in talk about baseball than politics, the backstop has become one of the most discussed and contentious elements of the Brexit negotiations. It is a simple basic principle, but no one is able to agree precisely how it will work.

What is the Brexit backstop?

Variously described as an insurance policy or safety net, the backstop is a device intended to ensure that there will not be a hard border between Northern Ireland and the Republic of Ireland, even if no formal deal can be reached on trade and security arrangements.

It would mean that if there were no workable agreement on such matters, Northern Ireland would stay in the customs union and much of the single market, guaranteeing a friction-free border with the Republic.

Both the UK and EU signed up to the basic idea in December 2017 as part of the initial Brexit deal, but there have been disagreements since on how it would work.

What are the main differences?

The first is over where it will apply. The EU wants the backstop to affect only Northern Ireland.

Even though the aim is for it to never come into force, Theresa May has ruled out the idea of separate customs arrangements for Northern Ireland and the rest of the UK – the so-called customs border in the Irish Sea – and it would be completely unacceptable to the DUP.

May has tried to argue that the backstop could apply to the whole of the UK, but this angers Conservative MPs, who dislike the idea of the country being tied to EU rules in the long term.

The UK has sought to make the backstop time limited, but Brussels argues this is impossiblebecause the guarantees it offers are needed for as long as an alternative solution is not found.

What is the ‘backstop to the backstop’?

This is the idea, being briefed by UK government sources on Monday, that Brussels is said to be seeking if it agrees to a UK-wide backstop. This would be a secondary guarantee, covering just Northern Ireland, if the first incarnation fails.

This has again been rejected by No 10, because it leaves the possibility open of customs divergence between Northern Ireland and the rest of the UK.

The idea is being held up as the reason talks have stalled ahead of this week’s EU summit, but this has been met with some scepticism in Brussels.