We are now entering the final stage of Article 50 negotiations with the EU. The meaningful vote is due by or before 12th March, setting a deadline less than two weeks from today; and the Attorney General, Geoffrey Cox, will take centre stage in the Brexit endgame. As the EU have stubbornly refused to reopen the Withdrawal Agreement itself, Cox’s aim is to secure a legally-binding protocol on the backstop. The hope is that this will enable him to update his legal advice, which currently sets out that the backstop could exist “indefinitely” if negotiations on the future UK-EU trade deal break down. History shows that when the EU’s refusal to renegotiate collides with the reality of domestic politics in a member state, Brussels has shown flexibility to facilitate ratification. Crucially, the legal instruments favoured by Brussels – protocols, addendums – have legal force even if the treaty itself remains untouched. At Open Europe, I have recently published a briefing which outlines historical examples of the EU revisiting a trade deal which was supposedly done and dusted. None are perfect analogies for the backstop impasse, but they illustrate wider points: that the EU is more flexible than it seems, and that it isn’t over until it’s over. In 2009, the Republic of Ireland secured legally binding guarantees which enabled it to ratify the Lisbon Treaty. This included a commitment to a protocol, later annexed to the Lisbon Treaty, which clarified that the Treaty did not compromise Ireland’s sovereignty in several sensitive areas – abortion policy, tax policy and military neutrality. Whilst this did not directly contradict the provisions of the Treaty itself, it shut down unfavourable consequences of the Treaty which Irish voters feared. Although the UK’s case is a question of ratification by MPs, not voters, there is a parallel here. Many Brexiteer MPs object to the backstop not so much because of its substantive provisions, but because they fear the UK could end up ‘trapped’ there permanently. The EU may insist this is not its intention, but only by putting this commitment into stronger legal terms can they hope to win enough MPs over. Ireland also convinced the Council to agree to legally-binding terms that the reduction in the number of EU Commissioners, established as a default by Article 17 of Lisbon, would not go ahead. Then Taoiseach Brian Cowen said at the time: “Ireland wanted firm legal guarantees. We got them.” If Theresa May can stand up and tell her backbenchers something similar on the temporary status of the backstop, there is hope for the deal yet. Another example of EU flexibility came in 1992, when Denmark voted down the Maastricht Treaty. In the quest to unblock Maastricht’s passage, the Danes secured guarantees even stronger than those of the Irish. Though Maastricht itself was unaltered, its potential future effect in Denmark changed markedly. In particular, the European Council legally recognised two unilateral Danish guarantees recognising that any further integration in two areas – Justice and Home Affairs, and EU Citizenship – would be put to referendums in Denmark. This provided the Danish people with commitments in international law that they wouldn’t be sold out by a pro-integration government. The Danish example bears parallels to today’s conundrum too. A key reason why the DUP (and indeed other Northern Ireland Unionists) oppose the backstop is because it can be superseded “in whole or in part” – raising fears that a future UK government might abandon Northern Ireland behind in the customs union while Great Britain leaves. Bluntly, the DUP does not trust London, which is why it poured scorn on the unilateral commitments offered by the UK to Northern Ireland in January. However, if the EU were to give legal recognition to these and other unilateral commitments, this would lend them much more weight. It did so for Denmark; it can do so for the UK. There are two other examples of the EU offering legal guarantees to get a deal over the line. In 2016, a Joint Interpretative Instrument on the EU-Canada deal helped overcome the objections of the Wallonian regional parliament in Belgium. In the same year, another legal instrument – an addendum – was used after voters in the Netherlands rejected the EU-Ukraine Association Agreement in a non-binding referendum. These examples are less directly analogous to the backstop, but add further weight to the broader point that the EU can be flexible when it needs to be. Many argue that the EU can’t, won’t or shouldn’t offer the same kind of concessions for the UK as it would for a non-departing member state. But this is an unreasonable argument which makes a virtue of inflexibility – and also flies in the face of the evidence that the EU is prepared to at least consider additional guarantees for the UK. The key question will be what guarantees Cox can obtain from the EU, and what legal effect they will have. Even Brexiteer MPs are now recognising that substance matters more than form, and are no longer insisting on a reopening of the Withdrawal Agreement. It remains to be seen what the new legal scrutiny group, fronted by Sir Bill Cash and Dominic Raab, will make of ‘Cox’s codicil.’ But if the EU is willing to show the same flexibility that it has done in the past, then a smooth, timely Brexit is still possible.