1) The grounds on limiting constitutional rights. Absolute rights
First of all, we should understand that almost all rights can be restricted because the freedom of these rights can be restricted in case if it interferes to another right. It means that you can use your right if it doesn’t another one. So there are, as usual, no absolute rights. For example, we can consider the practice of the European court of human rights which considers questions within the European convention on human rights. There are some rights, established in the first part of some articles, and the second one establishes restrictions on these rights. Such a list varies sometimes but as a rule is similar. There are, for example, right to fair trial (art. 6), freedom of private life (art. 8), freedom to expression (art. 9), freedom to religious views (art. 10), freedom of assembly and peaceful assembly (art. 11), prohibition of discrimination (art. 14) and so on which can be restricted sometimes. First of all for such restrictions there must be further criteria:
a) it must be provided by law. There must be a provision in a constitution or in a statute which restricts this right.
b) it must be reasonable. There must be a reason to restrict such a right.
c) it must be proportional to restrict a right. The European court of human rights exams whether it is proportional to establish such a restriction within criteria whether it is necessary in democratic society.
If some circumstances proves that these circumstances are established by a law, reasonable and proportional it can be qualified as restriction but not a violation of rights.
Also there is a list of certain grounds for such restriction, provided in the European convention on human rights. It’s suitable restriction if usage of some rights violates public order, morals or rights of other. Also there can be other restrictions on other grounds provided in national system. Also it is important to mention that it depends on a country which concrete restrictions are established in national system. For example, in countries of religious family there are restrictions on some rights which don’t fit for European concept of human rights in Europe. Also in the USA it is possible to restrict right to life if somebody commits severe crime by depriving life of a person within a death penalty. But it is impossible within the Europe.
As concerns absolute rights they cannot be met often, but they exist. For example, prohibition of torture is an example of such a right. It means that in any case they can’t be restricted even on the grounds mentioned above.
2) Case of Tanase v. Moldova
This case is interesting one because it touches art. 3 of protocol №1 which establishes some guaranties of free elections within reasonable intervals by secret ballot, under conditions establishing the free expression of the opinion of the people in the choice of the legislature.
Practice of these article depends from case to case. Sometimes The European court of human rights (hereinafter — the court) says that there are legal restrictions but sometimes that there is a violation. In this case the court said that it is not proportional to restrict this right within the obligation to have single citizenship. So there was a violation of right. But on the other hand we can understand that the requirement to have only one citizenship is proportional sometimes. For example, if it is a president or somebody else important it is obvious that he/she must be citizen of a country if double (multiple) citizenship is not allowed. In my opinion in these circumstances we can see that the court interprets this right too widely. I’d like to say that it is better to leave this right within the margin of appreciation of a state. Of course, there are a lot circumstances to say that it is not proportional, but for the security of the state such an approach can be applicable at least during the conflict with Transnistria. I agree that in the parliament there can be representatives of other peoples but at the same time such approach can destruct state’s identify as Moldavian state. If it is Moldova and there is single citizenship and there is conflict with its territory it is very difficult to find the right proportionality between restriction and violation.
As concerns if this situation was in Ukraine let’s begin with the fact that double (multiple) citizenship is not allowed in Ukraine. We have a lot of citizens who have other citizenship (for example, Russian, Polish, Belarussian ones). And they use their double citizenship to have some advantages (for example, to have two pensions). So single citizenship is established by the Constitution of Ukraine (art. 4) and the special law on citizenship and that’s why there is this restriction because it is political right and it is important for the state with single citizenship to have requirement for a deputy to have only a Ukrainian citizenship. So we can see that there is legal basis. It is reasonable for Ukraine because if it is a unitary state it must be some guaranties for the stability of the state. So there is a reason. As concerns proportionality let’s say that if there is no such requirement it can be dangerous for the unitary state to give possibility to be elected for representatives of other nationality. Also it is important to mention that it is political right and it’s sometimes the right only of a citizen.
At the end, let’s come back to the notion of the citizenship. It is connection between a state and a person. If there is no such a pure connection how is it possible to represent a state being elected? Of course, everything can be proved and it can be said it is not proportional but it depends on argumentation and features of a state.