What is Article 50? The only explanation you need to read

What is Article 50? In 60 seconds Watch | What is Article 50? In 60 seconds

Brexit is the greatest disaster to befall the European Union in its 59-year history but the referendum in which British voters opted to leave the European Union does not automatically signal the country's exit. That is the job of Article 50.

Britain's complex negotiations to exit the EU can only begin when Article 50 of the Treaty of Lisbon is formally triggered by the UK

What is Article 50?

The road ahead is unclear. No state has left the European Union before, and the rules for exit  – contained in Article 50 of the Treaty of Lisbon – are brief. 

The Lisbon Treaty, which became law in December 2009, is designed to make the EU "more democratic, more transparent and more efficient" and is an agreement signed by the heads of state and governments of countries that are EU members.

What is the difference between a 'Hard' and 'Soft' Brexit? Watch | What is the difference between a 'Hard' and 'Soft' Brexit?

When will it be triggered?

Theresa May has finally revealed that she will trigger Article 50 on March 29. That means Britain should officially leave the EU no later than April 2019.

Theresa May: Article 50 will be invoked by March 2017 Watch | Theresa May: Article 50 will be invoked by March 2017

How long will it take?

The process is supposed to take two years but many people believe that it could take longer.

The timescale can be extended, but only by the unanimous consent of the European Council. So every other member state Government would have to agree.

Triggering Article 50, formally notifying the intention to withdraw, starts the clock running. After that, the Treaties that govern membership no longer apply to Britain. 

The terms of exit will be negotiated between Britain’s 27 counterparts, and each will have a veto over the conditions.

It will also be subject to ratification in national parliaments, meaning, for example, that Belgian MPs could stymie the entire process.

Two vast negotiating teams will be created, far larger than those seen in the British renegotiation. The EU side is likely to be headed by one of the current Commissioners.

Untying Britain from the old membership is the easy bit. Harder would be agreeing a new trading relationship, establishing what tariffs and other barriers to entry are permitted, and agreeing on obligations such as free movement. Such a process, EU leaders claim, could take another five years.

Business leaders want the easiest terms possible, to prevent economic harm. But political leaders say the conditions will be brutal to discourage other states from following suit.

What happens after Article 50 is triggered? Watch | What happens after Article 50 is triggered?

How could the UK create a new life outside of the EU quickly?

One option will be to simply recreate EU laws as British statute. But Civil Service insiders expect a new Brexit government to opt for something much more radical, and to use the opportunity of “throwing off the shackles” to re-regulate Britain.

It means that the Government would have to perform three acts simultaneously:

  • Negotiate a new deal with Brussels
  • Win a series of major bilateral trade deals around the world
  • Revise its own governance as EU law recedes

Running the show would be an effective “Ministry for Brexit”, under a senior minister.

Officials expect the scrapping of EU law could result in an avalanche of new legislation in every corner of Whitehall – perhaps 25 Bills in every Queen’s Speech for a decade.

Hundreds of Treasury lawyers and experts would have to be hired for areas – such as health and safety, financial services and employment – where Britain had lost competence to Brussels. Meanwhile, a Trade Ministry will be required, with hundreds of new negotiators, to establish new deals around the world.

Government wins backing to trigger Article 50 by 494 to 122 Watch | Government wins backing to trigger Article 50 by 494 to 122

Could the EU come down hard on Britain?

The focus in Brussels now turns to holding the project together, which means they could drive a hard bargain in negotiations with Britain.

Jean-Claude Juncker, president of the European Commission, has called for tighter integration and has previously laid out plans for integration of the Eurozone, including a treasury, in order to prevent a recurrence of the Greek crisis. Member states have not been ready for that conversation – but the crisis of Brexit could push it up the agenda.

Jean-Claude Juncker, president of the European Commission, meets with David Cameron following the UK's decision to leave the European Union Credit: EPA

At the same time, leaders fear that Brexit could trigger a domino effect as the bloc without Britain becomes less attractive to liberal, rich northern states such as Denmark and the Netherlands, where demands are growing for copy-cat plebiscites.

The Dutch elections are held in March next year, the French in April and May and Germany in the Autumn. If an independent Britain proves to be a success, the bloc could quickly unravel.

On March 25, 2017, European leaders will mark the sixtieth anniversary of the signing of the Treaty of Rome, the EU’s founding document. It will be a fraught celebration.

What about the rights of British expats and EU nationals living in the UK?

British expats living across Europe and EU nationals who live in the UK have expressed concerns about their right to residence following the Brexit vote.

It is unclear whether they will be allowed to remain - and it has become a particularly thorny issue in the Conservative leadership election.

Theresa May faced a backlash from her own supporters over her refusal to guarantee the rights of EU nationals living in the UK.

Theresa May launching her leadership bid Credit: Getty Images

Senior Conservatives backing Mrs May in the leadership contest have attacked her for saying that she cannot give any assurances to EU nationals because it will be a factor in the upcoming Brexit negotiations.

James Brokenshire, a Home Office minister and key backer of Mrs May, suggested in the Commons that any guarantee given to EU nationals could increase levels of immigration to the UK as people flock to the UK before Britain finally leaves the bloc.

Philip Hammond, the Foreign Secretary who is also supporting Mrs May, said that it would be "absurd" to guarantee that EU nationals can continue living in Britain after the UK leaves because their status would have to be factored into the terms of Britain's exit.

Andrea Leadsom and Stephen Crabb, two of Mrs May’s rivals for the Tory leadership, have both demanded that the Government guarantees the rights of EU citizens living in the UK.

At her leadership launch, Mrs Leadsom said: “I commit today to guaranteeing the rights of our EU friends who have come here to live and work.

"We must give them certainty there is no way they will be bargaining chips in our negotiations."    

In Parliament, a series of Conservative MPs attacked the decision not to pledge to guarantee the rights of EU citizens.

What does Article 50 actually say?

There are five elements to Article 50 of the Treaty of Lisbon:

  1. Any Member State may decide to withdraw from the Union in accordance with its own constitutional requirements.
  2. A Member State which decides to withdraw shall notify the European Council of its intention. In the light of the guidelines provided by the European Council, the Union shall negotiate and conclude an agreement with that State, setting out the arrangements for its withdrawal, taking account of the framework for its future relationship with the Union. That agreement shall be negotiated in accordance with Article 218(3) of the Treaty on the Functioning of the European Union. It shall be concluded on behalf of the Union by the Council, acting by a qualified majority, after obtaining the consent of the European Parliament.
  3. 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.
  4. For the purposes of paragraphs 2 and 3, the member of the European Council or of the Council representing the withdrawing Member State shall not participate in the discussions of the European Council or Council or in decisions concerning it. A qualified majority shall be defined in accordance with Article 238(3)(b) of the Treaty on the Functioning of the European Union.
  5. If a State which has withdrawn from the Union asks to rejoin, its request shall be subject to the procedure referred to in Article 49.