Britain looks on course to leave the EU. This is having an immediate effect on markets. It will have immediate political ramifications too. David Cameron will, fairly soon, need to decide if he can continue in his role as British prime minister.

Legally speaking, though, the process of actually leaving will take a lot longer. Britain will now enter a kind of phoney Brexit period. It is still a member of the EU. The referendum vote is not as such legally binding. It is advisory only – but if it is out it creates a political imperative for the UK government to arrange its exit of the EU.

The law governing Brexit is found in Article 50 of the EU Treaty. This is a provision adopted by EU member states in 2009 to govern Brexit-like scenarios. It puts a two-year time limit on withdrawal negotiations. When the two years is up (or on the date any agreement reached before this enters into force) the UK is officially out of the EU.

Article 50 requires the UK to trigger the exit process by notifying its intention to withdraw. Not one, but rather a cascade of agreements, will follow this Brexit notification:

1. The Article 50 exit agreement
2. A separate treaty governing the UK’s future relationship with the EU – which could take many years to negotiate (and which, if it goes beyond trade, will require ratification by every single EU member state)
3. Trade agreements between the UK and up to 134 other WTO members
4. A tidying-up treaty between all the remaining EU states that removes all references to the UK from the EU treaties.

The initial main focus, however, will clearly be the Article 50 Brexit agreement.

How will it work?

The UK would be the first state to leave the EU but it is most likely that the European Commission, the executive arm of the EU, will do the negotiating on behalf of the remaining 27 member states. They will no doubt cast a watchful eye on proceedings, before voting on the deal.

That vote will be by a weighted majority, with bigger states like Germany, France and Italy having a more powerful voice than smaller members (although in practice, strong efforts are made to ensure every member state can live with a deal before a matter is approved). Above and beyond this, should the Article 50 Brexit agreement venture beyond trade matters, it will then need to be ratified by every EU member state.

The European Parliament has a veto option, making it an important player too. Article 50 negotiations will thus have a lot of players with powerful voices – and many not necessarily be inclined to give the UK a very favourable deal lest “exiters” in their own countries get any ideas.

Powerful voices at play. EPA/Patrick Seeger

Could the UK delay giving Article 50 notification?

Legally, yes, the UK could delay giving Article 50 notification or avoid it altogether. But other EU states will probably refuse to negotiate until they get the notification.

Brexit campaigners have suggested adopting a swathe of domestic laws so that the UK can short-circuit Article 50. But such measures would violate EU law and probably won’t see the light of day. Enacting them would pointlessly violate EU and international law, alienate the UK’s future negotiating partners and jeopardise the UK’s future relationship with the EU.

Also, in terms of domestic politics, since referendum votes demand respect, it will be difficult to avoid providing the notification. Moreover, David Cameron has indicated he will give it, although it remains to be seen whether he will remain long enough in office to have to meet that commitment.

Can the UK withdraw notification?

This might be attempted if, for instance, the UK doesn’t like the way negotiations are going. It is unclear if it is legally permissible. The EU Treaty certainly doesn’t prohibit it in so many words. Political misgivings would abound – but might possibly be met by having a second referendum to reject any Article 50 deal ultimately reached.

Ireland, after all, had referendum second thoughts on the Lisbon and Nice Treaties, Denmark had them on the Maastricht Treaty and France and Holland agreed to a Lisbon Treaty deal very similar to the 1994 Constitutional Treaty earlier rejected by both states in referendum.

What will the UK get from negotiations?

That depends on how (and who) conducts the negotiations for the UK, and what the other states are prepared to offer it. Even assuming they prove pleasantly amenable, the UK will be left with awkward choices.

On the outside.EPA/Laurent Dubrule

Does it want continued access to the single market with its 500m consumers? If so, it is may have to make Norway-like concessions – including continued EU migration and cash payments for the privilege. Does it want to block out EU migrants? Then it may well have to say goodbye to single European market access.

No matter what the UK chooses, it will unavoidably find itself outside the corridors of power in the EU for the first time in over forty years.

Is there any way back in?

Article 50 does envisage the possibility of UK re-entry to the EU one day – but subject to a unanimous vote of member states. This pretty much guarantees it will only ever happen by the UK accepting the euro currency, participation in the Schengen area of free movement and no rebate.

Welcome to the brave new world of Brexitland.