Establishment of the administrative proceedings doctrine is a continuously evolving process, and one of its tasks is to create an appropriate array of concepts and categories. One of the central categories of the administrative proceedings is unlawfulness. The Code of Administrative Proceedings of Ukraine (CAP of Ukraine) does not define it as a separate legal phenomenon, but the sign of unlawfulness of decisions, actions or omissions is crucial when a plaintiff formulates claims seeking protection with the administrative court, on the one part, and when the administrative court formulates its decision – on the other part. Therefore, correct understanding of the content of unlawfulness in the context of tasks of the administrative proceedings is extremely important. Actually, within the framework of the administrative court’s activities aimed at considering and resolving administrative cases, it is unlawfulness of decisions, actions or omissions of subjects vested with power that is the central element of the fact to be proven.

The purpose of the article is to determine the content of the category of unlawfulness in the administrative proceedings and elucidate its importance and generic diversity in the context of various types of the subject matter of public-law disputes referred to the administrative court.

Based on the analysis of the grounds upon which the administrative court makes its decisions, the author shows that unlawfulness in the administrative proceedings is a property of decisions, actions or omissions of a subject vested with power which demonstrates their inconsistency with formal requirements of laws and other statutory instruments, the rule of law principle or the case law of the European Court of Human Rights (ECHR) entailing breach of the rights, freedoms or interests of individuals, rights and interests of legal entities. Unlawfulness is determined depending on the parameters of a subject vested with power or its activities; it may be of a formal, competence-related, process (procedure) – related or conceptual nature. The article focuses on the specifics of identifying unlawfulness in cases when administrative courts apply the rule of law principle and the ECHR case law. The author substantiates the standpoint according to which it is unreasonable to recognize as unlawful the omissions of subjects vested with power in cases when an administrative case is resolved on the basis of analogy.