The Vienna Convention on the Law of Treaties safeguards acquired rights to a significant extent. It had been claimed in the run-up to the Brexit referendum that it would safeguard the EU rights of UK nationals in the EU (and vice versa). However, the rights apply as between states and not individuals or corporate entities. If a treaty is terminated, Article 43 of the Vienna Convention confirms that it no longer creates or regulates the legal position.
There is a principle of acquired rights under customary international law which protects certain property and quasi-property rights. This principle arises, in particular in respect to investments of property and another asset, where the host state seeks to expropriate prior nationals. The rights are not expressed in treaty form but are accepted as general principles
The right should be vested and have an economic value. It should be generally capable of transfer. The scope of the right is relatively narrow under the customary international law. It would include in particular real and personal property, business goodwill, accrued pension entitlements, rent, bank deposits, court judgements and arbitration decisions. Civic or political rights, such as the right to reside are not acquired rights in this sense.
Where a company has exercised the right of establishment in the EU, it may have acquired rights in that particular establishment. However secondary rights indirectly acquired as a result of the establishment would not be protected. The right to establish itself would not be thereafter protected as it arises in EU law. It may, however, be protected by European Convention on Human Rights or the European Charter of Fundamental Rights in some circumstances.
International Customary Law and Individuals
It appears that there is little chance for using rules of international customary law in domestic causes of action. State action in this context may conceivably be the subject of judicial review or a judicial review type application to uphold the obligation of the state to comply with international law.
Acquired rights may arise in an international court, such as the International Court of Justice where or in an arbitral tribunal where a national affected, brings a claim against a state which has committed some wrongdoing, such as appropriation of the property without compensation. Such a claim in so far as it is admissible at all may only be brought after available domestic remedies were exhausted. Both states would have to agree to the jurisdiction of the tribunal, which would not necessarily occur.
It appears that the scope for arguing that acquired rights apply to protect former EU citizens who lose their citizenship on Brexit is weak. Such parties may ultimately qualify to become nationals and citizens of other EU states and thereby acquire a citizenship. They may be in a position to obtain dual citizenship in another EU states with which they have a connection.
ECHR and Deprivation of Acquired Rights
Issues of human rights commonly arise in the context of free movement and the status of EU citizens within UK and UK citizens within the EU. The Convention including, in particular, the rights of the family life and to process have been applied to significant effect in the context of migration and immigration within the EU. The Convention may continue to play a role in this context.
The European Convention on Human Rights declares that every natural or legal person is entitled to the peaceful enjoyment of his possessions. No one shall be deprived of his possessions except in the public interest and subject to the conditions provided for by law and by the general principles of international law. This provision does not impair the right of a state to enforce such laws as are deemed necessary to control the use of property in accordance with the general interest or to secure the payment of taxes, other contributions or penalties.
The European Court on Human Rights has recognised that possessions include real and movable and immovable property, intangibles, contracts, judgements, licences and public benefits. Legitimate expectations are an element of property rights which may be protected in certain circumstances. Where a person has a reasonable or legitimate expectation as to the lasting nature of a right. such as a licence permission, that right may be protected by the ECHR.
Right to Private and Family Life
The European Convention on Human Rights protects the right to private and family life. Everyone has the right to respect for his private and family life, his home and his correspondence. There should be no interference by a public authority with the exercise of the right except such as is in accordance with law and is necessary in a democratic society in the interests of national security, public safety or the economic well-being of the country for the prevention of disorder or crime, for the protection of health or morals or for the protection of the rights or freedoms of others.
The Article has been used in many cases involving the deportation of EU nationals, from EU whose right to reside has terminated. The right may assist in preventing deportations, particularly from a procedural/due process perspective, beyond the scope of the citizens the EU directives.
The right to private life includes the right to establish and develop relationships with other human beings, the physical and psychological integrity of a person as well as features that are integral to a person’s identity and ability to function socially.
Balancing of Private / Family Life and Public Interests
States have rights under international law to control the entry of non-nationals. The European Convention on Human Rights does not impose on the state, any general obligation with respect to the choice of residence of a married couple. The removal or exclusion of one family member from a state where other members are lawfully resident does not necessarily infringe the Convention, provided that there are no insurmountable obstacles to the family living together in the country of origin of the member excluded, even where this involves a degree of hardship for some or all members of the family.
Article 8 of the Convention is likely to be violated by the expulsion of a member of a family that has been long established in the State where it is not reasonable to expect the other members of the family to follow the expelled member to another state. Knowledge on the part of one spouse at the time of marriage, that the rights of residence of the other were precarious, militate against a determination that an order excluding the latter spouse violates the Convention rights of the former spouse.
Where the interference with the family rights is justified in the interest of controlling immigration will depend on the particular facts of the case and the circumstances prevailing in the state concerned.
It is arguable whether the ECHR can be invoked to preserve the rights of EU citizens as such in the UK or UK citizens in the EU, as EU citizenship will cease to apply. Arguments have been made that EU citizenship is a core part of social identity, whose loss could be subject to protection.
Article 14 of the European Convention on Human Rights provides that the enjoyment of the rights and freedom set forth in the Convention shall be secured without discrimination on any ground such as sex, race, colour, language, religion, political or another opinion, national or social origin, associations with a national minority, property, birth or another status.
An argument may be made that UK and EU citizenship can exist as in the same way as dual nationality generally. Citizenship of other states may be acquired under their national law. It could be argued that EU nationals who are not entitled to dual nationality could be held to be discriminated against contrary to Article 14.
The UK Supreme Court has held in another context that the denial of citizenship having an important effect upon a person’s social identity, is sufficiently within the ambit of Article 8 so as to trigger the prohibition of discrimination in Article 14 of the ECHR.
A third country national who enters the United Kingdom under a visa and lawfully remains is generally entitled to an indefinite right to remain after five years. After Brexit, the equivalent right under the Citizenship directive may not necessarily be extended to EU nationals in the UK as it would arguably constitute unlawful discrimination to treat former EU nationals better than third-country nationals.
In accordance of World trade organisation form a bilateral investment treaties investors who invest in other state are to be protected against discriminatory unreasonable and other measures expropriation and things — and expropriation. This covers financial assets, intellectual property, money, personal property et cetera. This may protect the economic rights but it is unlikely to protect rights to citizenship.