What are the options?
If Britain leaves the European Union, Britain’s future in Europe will be in the hands of the European Court of Justice (ECJ), which will decide on how it should be governed in the event of a hard Brexit.
But this is far from clear, with the British government and EU officials arguing that the court is too small and that it will not be able to tackle Brexit’s biggest challenges.
A new bill is being prepared to be presented in Parliament, which would give the ECJ a permanent seat in the European Parliament.
If the bill is passed, the ECW will also have the power to decide the rules governing Brexit and the relationship between the EU and the UK.
If that happens, the bill would set out how a British-run exit agreement would be negotiated with the EU.
The legislation would then have to be put to the European Council, the EU’s executive body.
In principle, that would make the EU very reluctant to reject a UK exit agreement, since the EU could then refuse to ratify the deal.
A referendum is also not likely, as the UK is not likely to be a member of the EU, and would therefore not be allowed to join the bloc.
It is possible, however, that Britain could opt to remain in the EU without a referendum.
The government’s Brexit negotiator, Liam Fox, told the BBC on Monday that it would be “highly likely” that a British exit would be accepted, but only if it was a “fair and democratic” deal.
Fox also said that Britain would “be able to have a relationship with the European Commission”, the European Economic Area, which is a bloc of 28 member states that includes the EU but is separate from the EU as a whole.
The EEA would have some of the same rules as the EU to govern trade and EU citizens’ rights.
If Britain wanted to negotiate a separate trade deal with the EEA, it would need to wait until a deal with EU members is signed before it could proceed.
How would a Brexit deal work?
The UK would leave the EU in 2019, and the country would join the EAEU, the bloc of 22 member states with a common customs union.
In 2020, a new trade deal would be agreed with the UK, and EU members would be expected to ratifiy it.
The UK then would seek to join a new free trade agreement, the Customs Union.
This would see the UK in a customs union with its neighbours, but would not require a referendum, which it has previously refused.
The final phase of Brexit negotiations would be to formally exit the EEU, which could happen as early as 2021.
This could be delayed until the end of the year, although the government has indicated it may want to extend the process until the middle of 2019.
What would happen next?
The prime minister would then sign a new agreement with the new trading partners, including the UK and the US, which he would then deliver to the UK parliament.
He would then decide whether to start negotiations with the rest of the EEC.
The deal would then be submitted to the EC, which will give the EU the power of veto.
If it rejects the deal, Britain would have to accept it as a new treaty, and could then negotiate a second one with the other EU countries, which, if the Brexit deal is approved, would then ratify it.
But if Britain wanted a second trade deal, it could wait until the EU gave its approval to the deal in 2019.
The process could then be repeated for the rest, including all the other countries in the EEE, which also have access to the single market.
If there is no agreement between the two sides, a referendum on Britain’s membership of the bloc could be held in 2019 or 2020.
How long will it take for Brexit?
The process of Brexit will take some time to complete, and is expected to take some years.
What is the UK leaving the EU for?
The EU will leave the UK on March 2019.
A period of transitional arrangements will be set up to allow for Britain to negotiate its own future.
Some of these could include the establishment of a customs and immigration zone, the reintroduction of the Northern Ireland border and the possibility of a post-Brexit trade deal.
But the UK has also indicated it would like to retain some of its existing rights and freedoms, including access to free movement of people.
This means that the UK will have to apply for access to certain EU citizens and other benefits.
The EU has the power under Article 50 of the Lisbon Treaty to decide whether Britain’s exit is a valid and irreversible exit, and to force it to return to the customs union if it so chooses.
It can also block any withdrawal that does not satisfy this condition.