Brexit backstop: What is the Irish border plan and why is it so controversial?

Everything you need to know about the most contentious part of Theresa May's Brexit plan

What is the backstop?

The backstop is, in short, an insurance policy.

It spells out what should happen if the UK and EU cannot agree a comprehensive trade deal that would maintain an open border between Northern Ireland and the Republic of Ireland.

Both sides say they do not want the backstop to ever become a reality, because they hope to reach a deal that would avoid a hard border.

However, the EU insisted on a fall-back to ensure the border will remain open even if no deal on the future relationship between the EU and UK is agreed.

The Irish government is particularly concerned that an open border be maintained, given it is a key part of the 1998 Good Friday Agreement that brought peace to the island of Ireland.

What would the backstop involve?

The backstop would see the UK enter into a temporary customs union with the EU. This would ensure there is no need for customs checks on goods travelling between Northern Ireland and the Republic of Ireland.

Northern Ireland would also abide by EU single market rules on goods. That would mean there would also be no need for regulatory checks of products crossing the border, allowing an open border to be maintained.

However – and there is always a however – the fact that Northern Ireland would effectively remain in the single market, while the rest of the UK would not, means there would have to to be new checks on goods travelling between the region and the rest of the UK. The EU has said most of these checks could be carried out in factories and farms rather than at the border, but for goods such as live animals this would not be possible.

The EU had initially pushed for the backstop to apply only to Northern Ireland, but Theresa May refused, saying she would not accept any situation in which the region had different customs rules to the rest of the UK.

Why is it so controversial?

The backstop is, by some way, the most contentious part of the Brexit deal. It was the subject of months of drawn out negotiations with the EU and is the main reason why so many MPs are opposing the proposed agreement, forcing Ms May to delay the House of Commons vote on her deal.

According to its critics, there are three main problems with the backstop.

Firstly, the UK would not be able to exit the mechanism without the EU’s approval.

After Brussels rebuffed Ms May’s attempts to secure a unilateral exit clause, the draft withdrawal agreement says the EU and the UK must “decide jointly” if and when the backstop is no longer necessary. If they disagree, the matter would go to arbitration.

Critics say this means the EU could keep the UK trapped in the backstop for as long as it wishes, with nothing the UK government could do about it.

The second point of contention is that the backstop is “indefinite”. There is no time limit on the protocol; instead, the withdrawal agreement says only that the provisions apply “unless and until they are superseded, in whole or in part, by a subsequent agreement”.

That is a major issue for Tory Brexiteers, who fear that the supposedly temporary arrangement could turn into the UK remaining in a customs union with the EU permanently, thus making it difficult to strike new trade deals with other countries.

The third problem is the one that most bothers the Democratic Unionist Party (DUP), which props up Ms May’s government in the Commons.

The Northern Irish party is furious that the backstop would see new regulatory checks introduced on some goods travelling between Northern Ireland and the rest of the UK. Staunch unionists fear this is the first step towards the break-up of the United Kingdom.

What does the government say?

The government insists there cannot be a withdrawal agreement of any kind without a backstop, because the EU demands one.

Ministers claim the protocol will not be needed and that neither side wants to see it implemented.

They say it will be temporary but admit that the UK would not be able to leave unilaterally.

The government’s legal advice, provided by attorney general Geoffrey Cox, said a permanent backstop would likely be illegal under EU law, and so could challenged – a point ministers have flagged in an (unsuccessful) attempt to win over Tory rebels.

Ms May has also said the UK would be able to choose whether to enter the backstop. This is because, if no trade deal is agreed by the summer of 2020, the British government will be able to express a preference as to whether to enter the backstop or extend the transition period to allow for further negotiations.

The transition is due to expire at the end of 2020, but the withdrawal agreement allows for it to be extended by up to two years. This would provide more time for a deal on the future relationship to be agreed, meaning the backstop would not be necessary.

However, the EU would need to approve the UK’s request. If the two sides disagree, the matter would go to arbitration. The UK could not, therefore, simply decide not to enter the backstop.

And if no deal is agreed at the end of the extension, the backstop would still be implemented. That is because it is the default unless and until there is something to replace it.

Ahead of the second meaningful vote, Ms May made an eleventh-hour dash to Strasbourg to secure three new documents that she says will give MPs the legally-binding reassurances they require to back her deal.

These include a “legally binding joint instrument”, which the government says will reduce the risk of the UK being held in the Northern Ireland backstop indefinitely, and commits both sides to replace the backstop “with alternative arrangements by December 2020”.

The package also includes a “unilateral declaration by the UK”, giving the government the right to take the EU to independent arbitration if it does not sincerely try to remove the backstop – and a political declaration setting out both sides’ commitments to speeding up the process.

This article was originally published on Tuesday 11 December 2018.