The Lisbon Treaty now provides for it officially: a Member State can leave the EU. In fact, it can just stop implementing EU laws overnight or, more sensibly, negotiate its exit. In any case, it'll all be over in max 2 years.

How It Works: Leaving the EU

https://api.multimedia.europarl.europa.eu/documents/20125/13756822/V003-0008-EN.srt

Hello, my name is José.   I come from Spain.

Is it possible for a Member State   to leave the EU?

Mr Farage, why don't we implement   Article 9 of the Treaty?

You could ask to leave the EU   and never worry about it again.

EPP Chair Joseph Daul said it during   Van Rompuy's first visit to the EP:

It's now in black and white;   a novelty of the Lisbon Treaty.

A Member State willing to regain its   sovereignty must first notify the Council.

The withdrawal negotiations then follow.

The Member State doesn't have   to discuss it with the other states.

and stop implementing EU directives   overnight.

Or, it has two years   to negotiate its withdrawal.

Great Britain   tried to leave the EU in 1975.

It organised a referendum,   but 67,2% chose staying in the EU.

In 1973, Greenland joined the EEC   as a part of Denmark.

Upon gaining home rule   the island withdrew from Europe in 1985.

The Treaty had to be modified   to allow for the withdrawal.

Today, no veto can prevent   a Member State from withdrawing.

The Council will negotiate the agreement   on the terms of withdrawal

The agreement will define the relations   between the EU and the former Member.

The country will always be able to rejoin

but it will have to apply again   like any other candidate country.

Is it possible to leave   or be expelled from the Eurozone?

Mrs Merkel launched the debate   in the Bundestag.

But, for now,   EU rules don't provide for it.

So let's recap. A Member State   can leave the EU whenever it wants to.

After the official request,   the withdrawal can take up to 2 years.

by going through the accession process   like any other candidate.