Can Westminster unilaterally stop the Article 50 ticking clock which was triggered by Theresa May in March 2017, and is set to chime in March next year?

After hearing the case today, the ECJ will retire to consider a verdict – and we’ll be told the answer in the coming weeks.

The case was brought by a cross-party group of Scottish politicians, including me and my Labour MEP colleague David Martin. The team also includes Green MSP Andy Wightman, who has been leading from the front, as well as his colleague Ross Greer, SNP MEP Alyn Smith and SNP MP Joanna Cherry.

An anti-Brexit demonstrator dressed in a Union flag suit waves an EU flag outside the Houses of Parliament. Picture: AFP/Getty

Throughout the process we have been backed by Jolyon Maugham QC of the Good Law Project, and we’re incredibly grateful for the support we have received from all those who donated to the crowdfunding appeal.

Legal cases like this don’t come cheap. But this is not some publicity stunt or futile endeavour – it’s a vital test to find out if we can call a halt to the Brexit catastrophe.

Everyone involved in this fight campaigned hard against Brexit in the 2016 referendum. We knew that leaving the EU would cost jobs, stifle economic growth and put workers’ rights at risk.

When we need solidarity between nations more than ever, breaking away from this unique partnership was never going to be the best choice for our country.

But we lost the contest following a referendum where the Leave campaign lied and cheated, peddling myths about NHS funding and scaremongering about immigration.

In the immediate aftermath of that vote, there was a need for calm and cool heads. I still shudder when recalling how Jeremy Corbyn – a lifelong Eurosceptic – said we should immediately trigger Article 50 the following morning.

The Prime Minister took a bit more time and pressed the button on March 29, 2017. But she did so without any knowledge of what the Brexit deal would look like.

There had been no negotiations with EU member states; no agreement within her Cabinet. She started the two-year clock ticking without a clue about what she could achieve. It was an utterly reckless decision by a Prime Minister which generations of history students will learn about for decades to come.

The UK Tory government gave the impression that that was it: the decision was final.

But Lord Kerr, the author of the Article 50 notice, has said the Government can withdraw its letter and stop the process if it wishes to.

Jean-Claude Piris, the former head of the European Council’s legal service, has also said: “Article 50 is based on the principle that withdrawing from the EU is a unilateral decision. Nobody can force a state to leave.”

So we lodged papers in the Scottish courts, seeking a ruling from the national court to the ECJ for a definitive ruling – bearing in mind that the Article 50 process has never been used before.

Our first attempt failed – a Court of Session judge initially felt the issue was hypothetical as the UK Government had stated it did not intend to halt the process.

But our appeal was successful, as Scotland’s most senior judge, Lord Carloway, determined it was clear – in terms of the European Union (Withdrawal) Act – that MPs will be required to vote on whether to ratify the Brexit deal.

It is neither academic nor premature to ask whether it is legally competent to revoke the Article 50 notification.

The Court of Session sent a reference to the ECJ seeking a ruling, but the UK Government – in an act of sheer desperation – lodged an appeal at the Supreme Court in London. This was quickly dismissed, as the court confirmed it is the ECJ which “must assume responsibility for the subsequent judicial decision”.

So that is how we have got to today.

Since the legal process began, “Chequers” has come and gone, and the Prime Minister’s worst-of-all-worlds deal was agreed by the EU at the weekend.

It’s a bad deal for the economy with no guarantee of frictionless trade in the future; it’s a bad deal for workers with no guarantees that Britain will keep EU standards on workers’ rights; and it’s a bad deal for consumers with no guarantees on continued consumer rights.

The end of free movement will be harmful for economic growth here at home, but also for young people who will be denied the opportunity to travel, work, live, love and explore throughout the whole of the EU. It’s a deal which should be voted down by MPs in the Commons.

I very much hope the Luxembourg verdict is known before that meaningful vote takes place in Parliament. MPs should await the outcome, as a positive verdict would give them the option of pausing Brexit – not just picking between the dreadful choice of Mrs May’s deal or no-deal.

I am confident this alternative will be available. We must hold our nerve. We owe it to every voter in the UK to ensure that all avenues are fully explored.

Why are we running headlong towards this fork in the road where the signposts are ‘deal’ or ‘no deal’? Let’s pause before we reach the fork and reconsider our options.

Or – even better – let’s build an alternative path that’s signposted ‘people’s vote’. On this route we can put control back in the hands of the public – and let them decide if this Brexit chaos is really worth it.

Catherine Stihler is a Labour MEP for Scotland.

Catherine Stihler: Countdown to Brexit should be stopped before it blows up in our faces