Some are retired, some are studying and some are working. Up until now, they have been entitled to the same rights as any other EU citizen. That includes access to healthcare in any EU member state and access to certain child benefits. They also have the right to support when seeking work or for housing.
But what happens to these hundreds of thousands of people when their home country is no longer part of the EU deal? Will they all have to come home? They are facing just as much uncertainty about their future as EU citizens in the UK.
They are at risk of losing all their rights as EU citizens once Britain leaves the European Union. In the worst case scenario, they would have to leave the country, as they will lose the right to move and reside freely.
That is, of course, an extreme case, but more immediate concerns will be whether they will be denied access to public healthcare, whether students will have to start paying higher fees, and whether families could lose access to child benefits. Those working could be asked to apply a work permit of some form.
Article 20 of the Treaty on the Functioning of the European Union, which is one of the two main treaties establishing the European Union, states that every person holding the nationality of a member state shall be a citizen of the European Union. Taking this provision by its word means that as soon as Britain has successfully withdrawn its membership, Brits lose their European Union citizenship.
It will be down to the remaining 27 member states – not Britain – to decide how they interpret this rule. They will determine the status of Brits abroad and the rights that come with that status.
They might offer special status for a period of time, allowing UK citizens to stay where they are. They might, however, tie that to certain requirements such as language skills or the role the people in question play in their host society. Brits can always aim to naturalise into their host country, but that of course is a significant commitment.
A special case
They might be glad to hear, though, that the Court of Justice of the European Union (CJEU) has dealt with a similar situation and passed a judgement that might help them make their case.
This is the case of Janko Rottmann, a former Austrian citizen who ran into some trouble when trying to become German.
Rottmann lost his Austrian nationality when he became a German citizen – as under Austrian law, nationality is automatically revoked if a person is naturalised elsewhere. But it turned out that he had lied about his criminal convictions when applying for German citizenship. When the German authorities found out, they withdrew his citizenship, leaving Rottmann stateless.
It is entirely up to the national government of each European Union member state to decide how individuals gain and lose nationality. The CJEU did not question that. But connected to the nationality of a member state is the status of European Union citizenship. It had to look into whether Rottmann could be stripped of his European citizenship, too.
The court did eventually rule against Rottmann, but his case is still useful for Brits living abroad after Brexit. The CJEU did not allow Rottmann to keep his citizenship specifically because he had deceived the authorities. His criminal behaviour was what stood in his way.
The court is actually always keen to emphasise how European Union citizenship is fundamental and it did so in Rottmann’s case. It was only his criminal behaviour in the naturalisation process that allowed the member states to effectively withdraw his European Union citizenship status.
This is where the situation of British people living abroad differs significantly. They will not have had their nationality withdrawn due to criminal behaviour. They would be finding themselves in a unique position, where the state whose nationality they hold withdraws from the European Union and consequently strips its citizens of their European Union citizenship, including all of the rights attached to it.
It is uncharted territory, but what we do know, thanks to Rottmann’s case, is that the European court requires member states to justify any infringement of European Union citizenship rights. The court is clear that the consequences of such a decision for the person concerned need to be taken into account. This is where those who have been living abroad in Europe for years, who have retired there, who have raised their families there, should feel more at ease. The court will not easily allow their European Union citizenship rights to be withdrawn.