Brexit: Could Owen Smith really stop Article 50 and prevent Britain leaving the EU?

The Big Questions: Mr Smith plans to make the pledge an official Labour position if he wins the leadership race

Referendum voters were lied to by the Leave campaign, the Labour leadership contender insists (Getty)

Why are we asking this now?

Owen Smith has vowed that under his leadership Labour will vote against invoking Article 50, the untested protocol for leaving the European Union, until the Conservatives commit to a second referendum or a general election to approve any final Brexit deal.

“The British people were lied to by the Leave campaign – they deserve to have a say on whatever exit deal the Tories strike with the EU. Theresa May says that "Brexit means Brexit" – but nobody knows what Brexit looks like. It could involve trashing workers’ rights and environmental protections, opening up our NHS up to foreign competition, making it harder for us to trade with our neighbours and damaging our economy," the Labour leadership contender said in a statement.

He added: “I’m a passionate pro-European, and I will fight tooth and nail to keep us in the EU”.

“Under my leadership, Labour won’t give the Tories a blank cheque. We will vote in Parliament to block any attempt to invoke Article 50 until Theresa May commits to a second referendum or a general election on whatever the EU exit deal emerges at the end of the process. I hope Jeremy will support me in such a move.”

Ms May is expected to trigger Article 50, the formal process of leaving the EU, in early 2017 after government lawyers ruled out invoking Article 50 of the Lisbon Treaty this year. However, some reports have suggested the Prime Minister, who has repeatedly pledged to make a “success” of Brexit, could push back the timetable because her new Brexit and International Trade departments are not yet ready to enter the formal negotiation process.

Could Owen Smith’s plan work?

Theoretically, yes. The terms of Article 50, the untested protocol for a member state leaving the EU, mean that “any member state may decide to withdraw from, the Union in accordance with its own constitutional requirements".

David Allen Green, a prominent lawyer and writer, has previously said the phrase “in accordance with its own constitutional requirements” could mean either the Prime Minister making the notification as an “exercise of the prerogative, following the referendum vote” or “a prior parliamentary vote”.

“The fact is that the longer the Article 50 notification is put off, the greater the chance it will never be made at all. This is because the longer the delay, the more likely it will be that events will intervene or excuses will be contrived,” Mr Green added in a blog shortly after the referendum.

It is the understanding of Mr Smith’s camp that Theresa May would seek parliamentary approval, through a vote in the Commons, before formally notifying European member states of the country’s decision to leave the bloc.

Can MPs ignore the result of the referendum?

Geoffrey Robertson, a lawyer who has been counsel in many landmark constitutional cases, added shortly after the referendum that “MPs have every right, and indeed a duty if they think it best for Britain, to vote to stay” in the EU. He said that Parliament must repeal the 1972 European Communities Act, by which it voted to take us into the EU, before Brexit can be triggered.

“It is being said that the government can trigger Brexit under Article 50 of the Lisbon treaty, merely by sending a note to Brussels. This is wrong… the UK’s most fundamental constitutional requirement is that there must first be the approval of its parliament,” Mr Robertson added.

So, how would Owen Smith do this?

The Independent understands Mr Smith would make the pledge an official party position if he wins the leadership race next month, meaning he would whip Labour MPs to vote in line with the party’s leadership. Added with the evident opposition of leaving the EU from the Liberal Democrats, the SNP and the Greens, Ms May could theoretically be forced into accepting Mr Smith’s terms: a second referendum or a general election on whatever the EU exit deal emerges at the end of the process.

"I’m saying that we didn’t know exactly what we were voting on. We were fibbed to about the extra money to the NHS, we were fibbed to that there we were going to be getting easy answers to immigration," Mr Smith told BBC Radio 4’s Today programme.

"We could put it back to the country as a second referendum or a general election. I fundamentally believe that Jeremy didn’t fight hard enough. That we should stay in Europe. I think we can ask the question at the end of this – is Britain going to be better off or worse off as a result of Brexit?

But would he face a backlash?

Yes. Despite the ability and legality of the Commons to block the Brexit vote, MPs would be effectively ignoring the voice of Leave campaigners and the 17,410,742 people who voted to leave the EU in June. Many would likely see this a breach of democratic trust and with more than a third of Labour supporters believed to have backed Brexit, Labour MPs could risk alienating their constituents if they voted to ignore the vote to leave the EU.

Conservative MP and Leave campaigner Jacob Rees-Mogg told the Mail Online: "It is a direct snub to Labour voters. We would not have won the referendum without the support of a very large number of Labour voters, particularly in the north of England. Rather than listen to them he is now basically saying they are wrong."