Parliament is currently considering the European Union (Notification of Withdrawal) Bill. If enacted, it will authorise the Prime Minister to trigger Article 50, thus beginning the process whereby the UK will leave the EU. The Bill, as drafted by the Government, is very short indeed: the Government is evidently hopeful that Parliament will accept a Bill doing the bare minimum required by the Miller case, in which the Supreme Court held that legislation was necessary. But the Government has now accepted, in the course of today’s debate in the House of Commons, that there will be a vote in Parliament on any deal negotiated by the UK with the EU.

This might seem to put Parliament firmly in the driving seat: not only will Parliament (thanks to the Supreme Court’s intervention) trigger the Article 50 process, it will now also oversee the conclusion of that process. Indeed, the Shadow Brexit Secretary has hailed it as a ‘significant victory for Parliament’. The Government, then, will spend the next 18 months or so hammering out a deal with the EU — but it will ultimately be Parliament that decides whether what the Government manages to negotiate is acceptable. This, in turn, suggests that the Government is making a major concession to Parliament by giving it the final say over Brexit — or at least the terms upon which Brexit will take place and on which the UK’s future relationship with the EU will be based.

The reality, however, is likely to be very different. Until Article 50 is triggered, the withdrawing Member State remains in control: it cannot be forced out of the EU, and it cannot be required to initiate the exit process. However, once the Article 50 process is underway, the position changes markedly, as the third paragraph of Article 50 makes crystal clear:

The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period.

The logic of Article 50(3) is that the following potential scenarios arise:

(1)  Agreement within two years  The UK and the EU agree the terms of withdrawal within two years of Article 50 being triggered. The UK leaves the EU on the agreed terms.

(2)  Agreement to negotiate beyond two years  The UK and the EU reach no agreement on the terms of withdrawal within two years, but the UK and the other Member States unanimously agree to extend the negotiating period. The negotiations continue. The UK remains a member of the EU until an agreement is reached or until the extended negotiating period expires. The UK then leaves the EU in accordance with an agreement (if reached) or by virtue of the Treaties ceasing to apply (if no agreement is reached).

(3)  No agreement  The UK and the EU reach no agreement on the terms of withdrawal within two years. Nor do they agree to extend the negotiation period. The EU Treaties cease to apply to the UK two years after Article 50 is triggered. The very hardest of hard Brexits ensues.

Where, then, does a parliamentary vote fit in, given that any such vote is likely to take place near the end of the two-year negotiation period? The answer, it seems, is that Parliament will be presented with a choice that is, in reality, no choice at all. Parliament’s only options will be (a) to rubber-stamp the deal negotiated by the Government or (b) to reject the deal. If Parliament opts for (b), then what? The Government could seek to re-open negotiations, seeking better terms, but that would be unlikely at the eleventh hour. Or it could ask the other Member States to extend the negotiation period. But they might well say no. It follows that if Parliament — having been given its ‘say’ — chose to vote against the deal negotiated by the Government, the two-year wall might well be hit and the UK would then crash out of the EU with no withdrawal agreement whatever.

There is one caveat that should be entered. The foregoing analysis presupposes that the Article 50 process, once underway, cannot be unilaterally suspended or terminated by the withdrawing Member State. The question of Article 50’s unilateral revocability was not determined by the UK Supreme Court in Miller, all parties — including the UK Government — having chosen to argue the case on the assumption that Article 50 is not unilaterally revocable. The revocability question is, however, now being litigated in Ireland. If it turns out that Article 50 is unilaterally revocable, then that will be a game-changer — both in relation to the strength of the UK Government’s negotiating hand, and in respect of Parliament’s role. If the Article 50 process can be stopped by the UK, then Parliament could vote down any agreement towards the end of the two-year period safe in the knowledge that the Article 50 notification could be withdrawn and a cliff-edge hard Brexit avoided. With the Article 50 clock stopped, a variety of possibilities would open up — including further negotiations or even (if public opinion had sufficiently shifted) remaining in the EU.

The bottom line is that the UK’s position in relation to the EU and Parliament’s position in relation to the Government will be much stronger if the UK can revoke its Article 50 notification. That we still do not know whether that is possible is, to say the least, unfortunate. What makes it all the more unfortunate is that, as a result, Parliament is being asked to approve the triggering of Article 50 in return for the offer of a vote two years hence that — depending on the answer to the revocability question — will either give it considerable leverage or amount to nothing more than a worthless sop. Parliamentarians might be comforting themselves today with the thought that the Government’s ‘concession’ puts them back in the driving seat; but it is far from clear that there is actually any petrol in the tank.