Expansion of the grounds for loss of Ukrainian citizenship in the sphere of national security: the quality of law and the limits of state discretion

This article examines the expansion of the statutory grounds for loss of Ukrainian citizenship introduced by Law of Ukraine No. 4502-IX and Presidential Decree No. 110/2026, adopted in response to the security challenges posed by the armed aggression of the Russian Federation against Ukraine. Drawing on the doctrine of the three-part test for permissible restrictions of human rights (legality, legitimate aim, and necessity/proportionality) as developed in international human rights law and the case law of the European Court of Human Rights, the article evaluates whether the newly introduced mechanisms for the termination of citizenship meet the requirements of legal certainty and non-arbitrariness. Particular attention is paid to the ambiguity of the terms “aggressor state” and “occupying state,” the excessively broad formulation of “participation in armed aggression,” the relationship between citizenship loss and the principle of non bis in idem, and the absence of adequate procedural safeguards, including the right to be heard, in the administrative procedure established for the termination of citizenship. The article concludes that while the expansion of these grounds pursues the legitimate aim of protecting national security and state sovereignty, several provisions of Article 19 of the Law of Ukraine “On Citizenship of Ukraine” fail to ensure an adequate level of legal certainty, and it recommends that the terminology of the law be clarified and that appropriate procedural guarantees be introduced.