Camino Mortera-Martinez and John Springford (Centre for European Reform)
The new British government is facing very complicated negotiations in the coming years, which will see an agreement of the future relationship between Great Britain and the rest of the Union. A key issue will be the creation a legal framework for the continuation of the residency of EU citizens in the United Kingdom. However, the question remains if Britain can force citizens of other EU states leave the UK?
There are a number of legal, political and practical reasons why it would be difficult and per-haps even impossible. A very important reason is the prohibition of retroactivity, which is en-shrined in international law in the Vienna Convention on the Law of Treaties of 1969. According to this ban, any withdrawal from the contract should not damage the rights of the parties that were created while this contract was still in effect. However, there is no consensus among law-yers about whether this rule applies to the rights of EU citizens living in the United Kingdom as well.
However, even if the courts concluded that this is not the case, EU citizens may resist expulsion under British law, whose basic principles also include the need for legal certainty, and thus the impossibility of a retrospective change of terms and conditions. It is certain that the EU citizens who immigrated to Britain before the referendum of 23 June will have a particularly strong posi-tion in the event of any litigation.
Those who came after the referendum but still before the formal withdrawal from the EU will be in a slightly weaker position. The British government is concerned that there might be many people who would like to move to the country last minute, which is why it wants to announce the date after which the rights under EU law will no longer be guaranteed.
In practical terms, it is moreover a major problem to clearly distinguish when each EU citizen immigrated to Britain since the UK does not keep records of the incoming migrants. It would be naturally possible to set up a registry of foreigners living in Britain but not all of these people would be able to conclusively prove the date of their arrival. From a political point of view, Britain will need to obtain advantageous conditions for the UK economy, for which the good will of EU Member States will be needed. Thus, the UK can’t afford to provoke its European part-ners by trying to deport their citizens.