The UK can’t be forced to leave the EU or to join the euro

This week, the economist Andrew Lilico tweeted about a hypothetical scenario in which the UK cancels Brexit, but is then forced out of the EU in 2023 because we’d refuse to adopt the euro as our currency as required by the EU. 

 Mr Lilico is presenting a hypothetical situation here (rather than a factual claim), and he later clarified that his tweet was not saying that the UK would have to join the euro, or that 2023 was some kind of deadline for this.

However, given that the question of whether the UK would have to join the euro if it remained in the EU has recurred a lot recently, it’s still worth clarifying two points: the UK cannot legally be forced to leave the EU against its will, nor can the UK be made to join the euro by the EU (because the UK has an opt-out, and a veto over changing that opt-out).

The principle that a country can’t be expelled from the EU was re-confirmed in the ruling from the Court of Justice of the European Union in December 2018 on whether the UK can revoke Article 50, in which they wrote that a country cannot be “forced to withdraw from the European Union against its will”.

And it is not legally possible for the EU to force the UK to join the euro if it remains in the EU.

The UK has an opt-out from joining the euro. In the Lisbon Treaty it says that:

“Unless the United Kingdom notifies the Council that it intends to adopt the euro, it shall be under no obligation to do so.”

Experts at the Institute for Government and UK in a Changing Europe told us that, for this situation to change, the treaty establishing the UK’s opt-out would have to be revised or overridden.

But this would require all EU members to approve the treaty change. So (in a scenario where the UK remained in the EU) we would have an effective veto on any attempt to remove our opt-out from the euro.

Claims about the UK being forced to adopt the euro by the early 2020s were part of a highly inaccurate post about the Lisbon Treaty, which has been going viral for some months now. This has seemingly spawned a huge array of related claims about the prospect of the UK having to join the euro if it stays in the EU.

What could happen?

The EU could, in theory, apply heavy political pressure on the UK to join the euro or leave: if all other members decided to join the euro (currently 19 of 28 use the euro), the UK might feel compelled to either sign up to the euro, or choose to leave.

But experts at UK in a Changing Europe told us that this scenario is highly unlikely. They argue that the Brexit process has made clear that the other EU countries are keen to stop any further members leaving—and so trying to “force out” countries by pressuring them join the euro would run counter to their current strategy.

Donald Tusk, President of the European Council, has also clearly stated that he would welcome a decision by the UK to remain in EU.