We have until July to ask Europe for more time. How firm is that deadline?

Britain has left the European Union and entered a standstill transition period. We now have only months to negotiate future terms before we face a second cliff-edge. No sophisticated trade deal has ever been done so quickly—so we urgently need more time.

The Withdrawal Agreement struck with the EU says that if the UK lodges a request by July then an extension is possible. Yet the prime minister Boris Johnson is bullish about not extending: it has even been written into UK law that we will not do so. A crucial question is: what happens if we remain in denial and miss this date? If we reach November and are staring over the cliff, could we in practice still reach an agreement to delay? Or is 30^th June really the last chance?

The answer could determine whether the UK crashes out at the end of the year. Having spoken to politicians, ambassadors, lawyers and academics, my sense is that some improvised agreement could probably be struck. But it is far from certain, and any fudged extension will be a product of profoundly unusual technical wrangling, taking us even further into the legal and diplomatic unknown. This issue may reach a head in the months to come.

Of course Johnson, for his part, does not recognise the problem. “Our manifesto made clear that we will not extend the implementation period,” he has said, while banning staff from even using the phrase “no deal.” But the EU’s agreement with Canada took more than seven years. What if we do need last-minute help?

In the view of some, including Jean-Claude Piris, formerly the EU’s chief lawyer, Britain will simply fall off a second cliff edge. “The 30th June 2020 is a firm deadline,” he said, “provided for by article 132(1) of the Withdrawal Agreement. This is an international treaty which has now been ratified by both Parties and is legally binding for them.” That is the EU’s current line too and has been repeated by Chief Brexit Negotiator Michel Barnier. The exit terms agreed last year would be in force but with no deal for the future relationship.

Others however are less sure. If Britain requested an extension later, either to ratify or to continue thrashing out terms, might the EU find some way to accommodate that?

Helena Kennedy, one of the UK’s leading human rights lawyers, believes that “the EU will accommodate us if we decide we need more time and it also suits them.” John Kerr, the author of Article 50 and our former man in Brussels, said it is “do-able, if the political will existed on both sides, but quite complicated.”

David Hannay, Kerr’s predecessor, stressed that he was not certain but told me “my own experience of the EU over many years leads me to believe that, if towards the end of the year all parties were to conclude that extension was the least bad option, then the lawyers would find a way of giving effect to that.” Raoul Ruparel, former Europe adviser to Theresa May, has also suggested this would be possible.

Johnson has eaten his words before (the 31^st October was once a “do or die” date) and a late pivot may be in his interests if another no deal looms. Yet even at the more confident end, many I spoke to expressed legal doubts. That is because even with political will (which is far from guaranteed), you still have to create a viable legal route to an extension. And that is easier said than done.

The first legal obstacle is domestic, given that a transition extension is now unlawful in the UK. But a government with a large majority could see to that. “There is no reason—legally—why the government could not lay a simple amendment before parliament to allow for a further extension,” anti-Brexit campaigner Gina Miller told me.

Far trickier is the international side because this is not in the UK’s gift. It would involve wrangling at the geopolitical level. As Rhodri Thompson QC, an expert on EU law at Matrix Chambers, put it, “if nothing is agreed by the end of June then the only possibility seems to be another agreement between the UK and the EU, either amending the Withdrawal Agreement or as part of whatever new agreement may be reached during the course of the year, that would have the effect of extending the transition.”

The route usually suggested for amending something like the WA is the Vienna Convention, an international accord which regulates the drafting and amendment of treaties. Yet some worry that Article 50 is not actually a solid foundation for doing this. As Catherine Barnard, an EU law expert at Cambridge and the UK in a Changing Europe, told me: “The problem is that Art50 is about member states. And we are not a member state from 1st February, so there is considerable uncertainty about what the legal basis is for extending.” Others I spoke to, including Piris, voiced similar concerns.  

There is the possibility of a new agreement altogether. Yet obstacles remain. For whatever form this takes, it may well require the approval of 27 member states, each of them armed with a veto. “Possible, but not very likely,” said Dominic Grieve, former attorney general.  

There are still some alternatives. For Thompson, one option might be “some sort of complicated sector-by-sector and/or legal area-by-legal area agreement making special transitional provisions for issues such as agriculture or fishing or nuclear energy.” This sectoral option was cited to me by several experts as a way forward. Charles Grant, director of the Centre for European Reform, said: “My guess: there will not be a formal extension of the transition à la the withdrawal agreement. But there will be a de facto extension of large parts of the transition because in areas like security, research, education, services, investment, aviation etc there won’t be enough time to do deals this year.” We would have to continue paying into the EU budget over any lengthened transition period but perhaps something can be done.

Pascal Lamy, former director general of the World Trade Organisation, told me he thought there would be some form of second “implementation period” following the transition. “A future agreement will only enter into force after a ‘real’ transition period, during which the new regime will be gradually phased in in order to limit the cost of disruption,” he said. “My bet: four to five years,” meaning that “all in all, if Brexit happens, it will have taken 10 years.”

Ultimately, the UK and EU could simply go ahead, extend late in the year and dare someone to sue. But that is clearly not a happy state of affairs. Law can sometimes be bent to political reality. But the biggest danger for the UK is that law and politics coincide. As Kennedy put it, “it will be contingent on the state of play between us and the EU at that time. If we have really pissed them off they could stick to the letter of the law and call us out on our failure to meet the time limit.” Kerr and many others shared this concern. If Johnson asks for some last-minute help, EU agreement is likely. But it is far from guaranteed. Much better to request an extension in good time.