EU's Article 50: the rules for Brexit

There would be no catharsis for advocates of the "Leave" campaign as the process allows for up to two years of negotiation, after which the EU could present the UK with a deal.

“We should be clear that this process is not an invitation to re-join. It is a process for leaving,” Cameron said.

As Article 50 has never been used before, there is no clear framework of how those negotiations would work.

Article 50 says the member state wishing to leave needs to notify the European Council. The deal shall be concluded by the Council, “acting by a qualified majority, after obtaining the consent of the European Parliament”.

The EU treaties would not be applicable once the "withdrawal agreement" entered into force, but if there was no deal within two years after the notification, the EU rules automatically cease to apply to the country in question. Unless all 27 other member states agree to extend the negotiating period.

"No one knows how it would work," says Vincenzo Scarpetta, political analyst for the Open Europe think tank.

Article 50 does not specify how far reaching a "withdrawal agreement" should be; it is up to the negotiating sides.

Scarpetta points out that beyond trade agreements with 53 countries, the UK would have to negotiate on everything under the EU treaties – for instance agriculture, services, free movement of people.

But as it is not a part of the passport-free Schengen area or the euro, those areas do not require discussions.

As regards trade, the UK would have to decide if it wanted to join the trade deals in force now as an individual nation, or work out separate deals. But how that would play out remains an open question.

'Not Swiss cheese'

Negotiators would have to come up with a special model for the UK, as there are no precedents to follow.

None of the existing models for cooperation with the EU from the outside – Norway and Switzerland – represent what the UK seems to be most interested in: maximum access to the single market with some say in its operation, and maximum control over migration.

Norway, for example, has access to the single market, pays into the EU budget, but has no say in its rules and applies the same freedom of movement rules as EU member states.

An Open Europe article points out that in Norway’s case this resulted in far higher inward EU migration than the UK, when measured as a percentage of the countries’ total populations.

Switzerland and the EU operate on the basis of a complicated set of over 120 bilateral policy agreements, with the Swiss paying for a number of EU programmes.

A February 2014 referendum on limiting EU migration, effectively abandoning the commitment to free movement, threw the Alpine country's relationship with the EU in disarray.

Back then, European Commission vice-president Viviane Reding warned the result could jeopardise Switzerland's access to the single market, saying that "the single market is not Swiss cheese".

In return, Brussels blocked Swiss universities from European research projects, and students were denied access to the Erasmus exchange programme.

The proposed restrictions for EU workers are still not in place as Switzerland and the EU are negotiating ways for a new cohabitation, with the Swiss trying to avoid more retributions from the EU.

The EU tends to link access to the single market with free movement of people. That suggests the UK would have to accept some level of free movement.

"Would a deal for the UK involve full access to the single market for financial services, is anybody's guess," Scarpetta told this website.

Highly political process

A lot would depend on the dynamics of the negotiations and other member states.

"The economic interests of both sides would be to strike a deal," argues Scarpetta, adding that the deal should cover as much ground as possible.

While some member states might be disappointed with the UK leaving and hold animosity towards London, Scarpetta thinks the "hard logic" of the negotiations would eventually dominate the mood.

"There could be some emotions involved in the beginning of the talks, but pragmatism would prevail in the end," Scarpetta argues.

Fabian Zuleeg of the Brussels-based European Policy Centre says it is really up to the rest of the EU member states what kind of a negotiation they would want to have with the UK.

"The political realities would not be very accommodating to the UK," he argues, saying that it will be on EU negotiators' minds that a costless divorce which still gives access to the single market, would prompt questions from other member states.

"It is not in the political interest of the rest of the EU countries to concede a lot to the UK," Zuleeg says, as it might give the impression that cherry-picking from EU policies was a possibility, and other countries would ask for the same arrangements.

"While the legal framework is there, we are talking about a highly political process," Zuleeg points out.