When the UK voted to leave the EU in June 2016, even pessimists would not have predicted that 17 months after the British government triggered Article 50 we would still be waiting for serious negotiations to begin.

Theresa May’s enforced retreat from the moderately serious proposals in her Chequers white paper and her call for the EU “to evolve their position” show that, even at this late stage, the UK authorities still fail to understand the fundamental nature of the Brexit negotiation process.

The UK’s dilemma comes from the fact that the EU is both strong and weak. Externally, it is much stronger than the UK. It has a much bigger population and a much bigger economy. Certain parts of the EU, such as Ireland, will be very badly affected by a no-deal Brexit. But the union overall will suffer only moderate damage.

The UK, on the other hand, will suffer severe economic damage, and is desperate for a deal. The relative strength of the EU position means that calls for a fundamental change in the EU’s negotiating position are unlikely to succeed.

More importantly, the expectation that the EU will, or even can, “evolve” its position significantly fails to understand how the EU’s position is also constrained by weakness. The union is not a nimble negotiator. Michel Barnier’s negotiating position comes from a mandate that was agreed by the remaining 27 member states. Legally and politically, changing this mandate is very cumbersome.

May’s attempts to change the UK’s negotiating position required her to win the support of her cabinet and the House of Commons. Change to the EU position requires negotiations with 27 member states, and approval of any changes by a super-majority. In negotiations, therefore the EU is a lumbering colossus. It takes a long time to come to a position that it then finds difficult to adapt.

Internally weak

Most fundamentally of all, the EU is internally weak. Externally, as an enormous economic bloc the EU is extremely powerful. But internally the union suffers from a lack of independent democratic legitimacy and is fragile. For the vast majority of EU citizens their primary loyalty is to their state not the union, and most EU leaders are not directly elected. The enforcement of EU law and policy also depends to a great degree on voluntary co-operation by member states’ courts and civil servants.

The union is a package deal. Every member state dislikes certain aspects of EU law and policy, but is willing to put up with them because the overall EU package is beneficial. If the EU allowed the UK to cherry-pick the parts of the EU package it likes and to opt out of the parts it does not like then other states would seek the same, potentially leading to a wider unravelling of the EU as a whole.

A hard Brexit is less threatening to the survival of the EU than a soft “cherry-picking” Brexit.

May is, therefore, faced with an EU that is stronger than the UK economically and so does not need a deal as badly as the UK does, but which, because of its internal weakness, cannot give her the kind of deal she wants without risking its own existence.

British requests for a major evolution in the EU’s current approach were, therefore, always going to be a non-starter.

Brexit was always going to be either pointless (the UK stays in the Single Market but loses its ability to vote on Single Market laws) or disruptive (the UK leaves the Single Market and faces massive economic disruption).

When in January 2017, May, then at the height of her political power, set out “red lines” of leaving the Single Market and Customs Union and ruling out European Court jurisdiction, she was choosing, in effect, to opt for a disruptive over a pointless Brexit.

Miscalculated

Perhaps she did not appreciate the constraints under which the EU was operating and miscalculated. She may also have been putting off the evil day when she would have to face down the intensely Eurosceptic wing of her party.

Either way, the UK is now faced with the horrifying economic consequences of that choice of a disruptive instead of a pointless Brexit.

It would appear that the prospect of economic disruption has pushed May to change tack and to go for a more pointless, less disruptive Brexit than she previously sought. The problem is that she is trying to do so at a time when she has much less political capital than she had in January 2017.

Worse, her calls for a significant evolution in the EU’s approach suggests that 17 months after Article 50 was triggered and seven months before Brexit day, she still does not understand the fundamental constraints on the negotiation process imposed by the strength and weakness of the European Union. In these circumstances a no-deal scenario under which the UK crashes out cannot be ruled out.

Ronan McCrea is professor of constitutional and European law at University College London