Why we need to know about Article 50

There is no doubt there is a political route to revocability: if the other 27 agree, we can remain. But to improve the bargaining position of the UK, to ensure we retain the opt-outs and rebates that we presently enjoy, and to place the decision entirely in the hands of the UK's Parliament and - if it chooses - its people we must seek to establish a legal route to revocability. We must seek to secure a right for Parliament to withdraw the Article 50 notice - if it chooses.

The permission decision of the Court of Session will be handed down on Tuesday at 9.30am. I was warned before the hearing – once the judge was known – that we were likely to have a bumpy ride and so it proved. But we have a right to appeal to the Inner House and, should we need it, there is an appeal to the Supreme Court.

I believe we are right and the question should be referred. There are a number of reasons why I say this. But the main argument is this.

You cannot sensibly pretend that Parliament is not considering whether to revoke the Article 50 notice. The only amendment to the Repeal Bill that passed in the Commons opened the door to exactly that possibility. But don't accept my characterisation: it's exactly how (for example) Sir Oliver Letwin (speaking against it) put it. So did others.

In those circumstances it is vital that the UK Parliament knows whether it possesses that power. Indeed, it is vital that the EU27 knows whether Parliament possesses that power. And both need to know before the question whether to exercise it arises. If Parliament doesn't know then - should Parliament come to exercise the power - there will be chaos for the UK and the r27. There will be a period of many months in which we and they may not know whether the UK is inside or outside the EU. So it is not practical and it is not sensible to wait and see. When decisions of this magnitude are being contemplated the rules must be known in advance.

And there is no good argument to the contrary. None at all.

Stripped of legal niceties, all the Government can say is, 'we do not plan to revoke'. But (see that Oliver Letwin quote again) it is not for Government to decide. It is for Parliament to decide. (And, of course, both Governments and their positions can change.)

That is why I think it is important that we know the answer. And if, as I expect, Lord Doherty in the Court of Session disagrees and refuses to refer the matter to the CJEU it will be my advice to the seven petitioners that we should appeal to the Inner House of the Court of Session and, if necessary, the Supreme Court. (We have a right to appeal to the Inner House; we would need permission for a further appeal to the Supreme Court).

To do this we will need further funds.

As matters stand (in this case as in many others that I and the Good Law Project am and have been involved with) I am personally indemnifying the petitioners against the risk of costs falling upon them. I have no money other than what I have earned in a relatively short career at the Bar. That is a difficult financial burden to sustain in one piece of litigation; it is impossible across many.

So, if we lose on Tuesday, I will launch a further fundraising on Crowdjustice to protect us against adverse costs. You will have the opportunity to decide.

In the meantime, you can see our claim here.

You can see the Government's answers here.

You can see the affidavit of Joanna Cherry QC here.

And you can see the affidavit of Andy Wightman here.

And you can see the speaking note of Aidan O'Neill QC here.