Supreme Court Brexit Ruling: What Happens Next?

Supreme Court Brexit Ruling
Attorney General Jeremy Wright speaks outside the Supreme Court in Parliament Square, London, January 24. Stefan Wermuth/Reuters

Tuesday morning's Supreme Court ruling that the British government must seek the approval of parliament before triggering Brexit provoked an excited reaction.

Remainers took to Twitter to wonder if this meant the U.K. might not actually leave the EU, while leading Brexiter Iain Duncan Smith said the court had "stepped into new territory" it should not have entered.

But what does the vote actually mean, and what happens now? Here's what you need to know.

What has been decided?

The Supreme Court, the highest court on U.K. soil, has ruled that the government has to pass an act of parliament that approves it triggering "Article 50" of the Lisbon treaty, the formal mechanism for leaving the EU. The government is going to comply with that ruling.

That means Prime Minister Theresa May can't just pick up the phone to Brussels whenever she wants; she has to get parliament's permission.

So will this mean Brexit doesn't happen?

It's theoretically not impossible; as the court's judgment restated, the referendum on Britain's EU membership had only political force, not legal force.

In practice, though, it is very unlikely the House of Commons, Britain's lower house, would vote to block Brexit. The Westminster gossip blog Guido Fawkes, at the time of writing, had counted just 76 MPs who said they planned to vote against Article 50, out of a total of 650.

In the House of Lords, the unelected upper house, there is potentially a much larger body of support for blocking the trigger. But the government has put the Lords on notice. Speaking in the chamber Tuesday, Brexit Minister Lord Bridges said that as an unelected chamber the Lords "needs to tread with considerable care."

Rumors abound that the government might consider threatening the Lords with major reform if it doesn't vote to support the bill. Whether that happens or not, a vote against the government here would certainly be seen by the wider public as highly undemocratic, and many peers will be acutely aware of that.

So why does anyone care?

Even if Tuesday's decision doesn't stop Brexit happening, it might mean the government has to do more than it wants to, and could affect the timing.

The May administration plans to introduce the bill soon; "within days," according to Brexit Secretary David Davis. It will then hope to get this through parliament as quickly as possible so it can keep to its intended timetable of triggering Article 50 by the end of March.

But MPs from the government backbenches or other parties might seek to amend the bill, adding complexity to the process. The opposition Labour Party has said it will try and use the bill to force parliament to publish a formal "white paper" policy document on its Brexit plans, for example.

So has the government got anything it wanted?

Yes. During the court case, representatives of the devolved governments that exercise some powers over Scotland, Wales and Northern Ireland argued that the U.K. government at Westminster also had to get their approval to trigger Article 50.

The Supreme Court judges unanimously disagreed with that view.

But while this has saved the government a lot of potential delay—particularly in Scotland and Northern Ireland, which both voted to Remain—it might lead to problems in the long term.

Part of the devolved governments' case rested on the "Sewell convention;" an arrangement whereby the U.K. government would normally ask the devolved administrations' permission before legislating on anything that affected them.

The Supreme Court ruled that it could not force May's government to abide by this. But that doesn't mean the devolved governments can't get angry if the U.K. government chooses not to follow the convention.

In Northern Ireland, leaving the EU could affect its open border with the independent Irish republic to the south, raising fears of a return to the sectarian violence of the late 20th century.

While in Scotland, any sense that the U.K. government is riding roughshod over Edinburgh's separatist government will give it ammunition for a referendum on independence, as and when it decides to call one.