Some clues as to how the government intends to satisfy MPs’ demands for EU assurances on the backstop

Brexit: what can May hope to achieve in her dash to the continent?

Despite the calls emanating from parliament for Theresa May’s deal to be ripped up, gutted or trashed altogether, it is largely agreed in Downing Street and Brussels that the prime minister will not be able to reopen the text of the withdrawal agreement.

The European commission president, Jean-Claude Juncker, is instead offering “clarification and interpretation” of the terms of the deal and, in particular, the backstop solution for avoiding a hard border on the island of Ireland.

Quick guide Brexit and backstops: an explainer Show Hide A backstop is required to ensure there is no hard border in Ireland if a comprehensive free trade deal cannot be signed before the end of 2020. Theresa May has proposed to the EU that the whole of the UK would remain in the customs union after Brexit, but Brussels has said it needs more time to evaluate the proposal. As a result, the EU insists on having its own backstop - the backstop to the backstop - which would mean Northern Ireland would remain in the single market and customs union in the absence of a free trade deal, prompting fierce objections from Conservative hard Brexiters and the DUP, which props up her government. That prompted May to propose a country-wide alternative in which the whole of the UK would remain in parts of the customs union after Brexit. “The EU still requires a ‘backstop to the backstop’ – effectively an insurance policy for the insurance policy. And they want this to be the Northern Ireland-only solution that they had previously proposed,” May told MPs. Raising the stakes, the prime minister said the EU’s insistence amounted to a threat to the constitution of the UK: “We have been clear that we cannot agree to anything that threatens the integrity of our United Kingdom,” she added.

The backstop envisions an all-UK customs union to come into force at the end of the transition period should there not be an alternative arrangement available. Once in the customs union, the UK would not have any unilateral way to get out, leaving in tatters the Brexiters’ dreams of a buccaneering global Britain signing trade deals around the world.

The prime minister’s job, and that of both the European council president, Donald Tusk, and Juncker, is to convince MPs of the EU’s sincerity in neither wanting the backstop to come into force and, if that should come to pass, its desire to ensure it will be temporary.

Play Video 1:18 Juncker on Brexit: 'Withdrawal agreement will not be reopened' – video

There are some clues as to how the government intends to do this, and there are plenty of precedents in the history books of EU dealmaking to offer some insight into how those demands may be at least partially sated by Brussels.

What the government wants

A crucial insight into Downing Street’s thinking lies in an amendment put forward to the “meaningful vote” by the Tory MP Sir Hugo Swire. The government’s fingerprints were all over it.

Brexit: desperate May dashes to continent in search for concessions Read more

Beyond parliament directing the government on whether to seek an extension of the transition period to avoid the backstop, Swire more significantly proposed to place “a duty” on the government to agree a future relationship, or alternative arrangements, within one year of the Northern Ireland backstop coming into force.

It was essentially an attempt to give parliament a putative date by which the government would make all “best endeavours” to get out of the backstop, or have a very good reason for failing to do so.

The withdrawal agreement already says that the EU will make those “best endeavours” to have a free trade deal in place by 2020 – the end of the 21-month transition period. The government may well seek for the reiteration of that commitment, plus an additional statement of the EU’s intention to get out of the backstop by 2021.

How can it be done?

The legal minds in Brussels are past masters of coming up with vehicles for sweetening a deal.

The key for Theresa May is for her to be able to show MPs that whatever she agrees with the EU is legally enforceable.

The EU, meanwhile, will want to go as far as possible to help the prime minister without clashing with the content of the withdrawal agreement. There will be concerns about legally binding interpretations, for example.

The 27 member states will not set a time limit to the backstop. The question is whether Brussels could be willing to set a one-year target for getting out of it. The danger being that failure to reach such a goal could be used against it by the UK if it came to arbitration.

An internal statement by the 27 EU member states on their interpretation of the withdrawal agreement would be one way to set such a target or at least restate intentions, but it is unlikely to be enough for May. The same would go for a report at negotiators’ level.

A memorandum could be attached to the withdrawal agreement stating the EU and the UK’s intentions. But that again would not be legally binding on Brussels. Alternatively, European council conclusions are issued after every leaders’ summit, politically binding the 28 heads of state and government. Again, ephemeral to an extent but a legally-binding interpretation could be annexed. Such a ruse was one of the ways in which Cameron bound the EU to accept his terms of renegotiation should he have won the referendum.

The same was the case when the Dutch government initially rejected an association agreement with Kiev and wanted confirmation that it would not lead to Ukraine’s accession. Such an interpretation might even take the form of a side-treaty. For added drama, Theresa May could seek to have it deposited with the UN in case of need for international arbitration further down the line, as Cameron did with his deal.

Andrea Leadsom has additionally suggested that both the UK and European parliament could debate the backstop on an annual basis to ensure legitimacy. Such an agreement might be a nice garnish, but nothing more than that.