Theresa May's 'smooth and orderly Brexit' is emerging from the Westminster fog looking more like a British constitutional crisis.
The withdrawal agreement - needed in order to ease the transition to non-member status for the UK - was meant to have been signed and ratified last October after 18 months of negotiation. Instead the minority government lost two important votes last week and was found in contempt of parliament before the holidays.
The vote on the UK's withdrawal agreement with the EU-27 will finally be taken on Tuesday - and a heavy government defeat is predicted.
There are just three possible outcomes: the deal is agreed as negotiated (but there is no parliamentary majority); there is a no-deal crash-out at the end of March (most MPs are against this); or a deferral of the exit date, a course which would require an initiative by the government, which it is refusing to contemplate. The government has lost its authority and in normal circumstances there would be a general election. But May is planning to persist and Jeremy Corbyn's opposition cannot muster the votes to sack the government.
If parliament will not agree the May deal, and cannot replace the government, it cannot prevent a self-implementing exit just over 10 weeks away, without any withdrawal agreement and ensuring guaranteed chaos.
A no-deal Brexit will happen, with no transition period, on March 29 no matter how many resolutions to the contrary are carried by MPs. They can avoid no-deal only by voting for May's deal or by somehow engineering a deferral of the exit date.
How a rebel parliament could do this without the cooperation of the executive is uncharted constitutional territory. The UK can defer a March exit either by revoking the Article 50 resignation letter (since the European Court has ruled that it has the unilateral right to do so, in effect cancelling Brexit altogether), or by seeking an extension of the two-year notice period provided in that article and now almost exhausted.
To revoke the Article 50 notification - the simplest and cleanest means of avoiding no-deal - would keep the UK in the EU indefinitely in defiance of the 2016 referendum verdict. It would be hugely divisive but would see the UK retain all its current membership perks - a cut-price budget contribution, exemption from the Schengen passport-free travel arrangements and from the common currency and various opt-outs from social and justice policy rules.
The UK would re-attain the status quo ante as if the Article 50 resignation had never been submitted, including the entitlement to quit all over again whenever it chose.
An extension of the exit date beyond March 29, as distinct from a revocation, could be defended as just another delay in delivering what people voted for. But each of the 27 member states would have a veto on extension, which would be for a period measured in months and would need to be grounded in a convincing purpose like a second referendum rather than some nebulous re-opening of negotiations on the withdrawal agreement.
The EU will not, it would appear, countenance any re-opening. That book has been closed after what the EU see as substantial concessions to May in the deal which parliament is set to reject.
The December judgment by the ECJ, in restoring to the departing member state the unilateral entitlement to withdraw its Article 50 notification without any impairment of its previous position, provides the UK with a valuable option which the framers of Article 50 may not have intended. The perceived value of the option will rise weekly as the clock ticks, unless one of the alternative routes is chosen.
Should the UK seek instead an extension to the exit date for the explicit purpose of a second referendum, the EU-27 might feel honour-bound to concede it. An extension sought to prolong the can-kicking could see member states object as a unit or could see individual states deploy their vetoes. The Spanish would like Gibraltar, the Greeks the Elgin marbles, and every other member state could make demands - how about indemnities for the extra costs already incurred?
The shenanigans in Westminster have provided free schedule-filling material for the 24-hour news channels and endless copy for the print titles. But there has been precious little consideration of how this constitutional cul-de-sac has been arrived at.
The ultimate source is the resort, in June 2016, to the device of a 'consultative' referendum in an uncodified constitutional order supposedly built on parliamentary sovereignty. Add an unclear binary choice (where the 'Leave' option was ambiguous by design) to a minority government and the shambles is complete. If there is to be a second referendum it may well be the last until the United Kingdom makes itself a present of a codified constitution.
While Ireland's 1937 Constitution has not aged well (it is one of the oldest codified constitutions still operative in Europe) it is a model of clarity on the matter of referendums - when to have them, and how to interpret the result, the two missing ingredients in the UK.
Referendums in Ireland are for one purpose only, the specific amendment of the Constitution, and there is no requirement for interpretation, the endless divination of the 'will of the people' still droning on in the UK. The Irish Constitution has either been altered or it has not, the moment the returning officer sits down.
The 2016 vote was only the third national referendum in British history. The first, in 1975 on Europe, and the second in 2011 on the voting system, produced large majorities for no change. But 2016 produced a narrow majority for a very major change, but entirely unspecified. All three were called to resolve political problems for the government in office and the first to require change, in 2016, duly came unstuck.
To her credit, Margaret Thatcher foresaw the difficulties, or at least some of them, as leader of the Conservative opposition in 1975, and opposed the introduction of the referendum device on principle and never resorted to it in 11 years in Downing Street, her late-career scepticism about the EU notwithstanding. The UK has burdened itself with an impossible trinity - an uncodified constitution, parliamentary sovereignty, and 'consultative' referendums.
While acceptance of the May deal does not currently command a Commons majority, it could eventually succeed for the want of a tolerable alternative. It is a terrible deal for the UK though, delivering a short reprieve while seeking a brand-new trading relationship with the EU and the rest of the world.
A foretaste of what lies in store was offered last week by the European Commission, which queried whether the IAG group (which owns British Airways, Iberia and Aer Lingus) could continue to be classed as a European airline without divesting some of its non-EU shareholders.
Every protectionist interest in Europe, and they are legion, will seek to screw the Brits in the free-for-all of the trade talks to come. And there will be equally challenging trade talks with China and Donald Trump's USA, to be conducted in competition with the EU-27 as the re-set clock ticks down to a reincarnated cliff-edge at the end of 2020.
In comparison to an immediate no-deal, May's deal is just a nightmare postponed.