The legal force of an administrative act determines its validity, affects the powers of an administrative body that adopted this act to change or cancel it, and the legal force makes the act binding on every administrative authority and every person interested in this act. This term has not yet been fully studied and is absent from Russian legislation. There are some questions about the implementation of the theory of the substantive and formal legal force of an administrative act into the doctrine. There are also problems of the relationship between the legal force of the original act and the act derived from it. It is necessary to clarify the possibility of using administrative discretion when resolving issues of the legal force of administrative acts.

         To research legal force of an administrative act, traditional methods of legal study were used, especially the historical-law method and the comparative law method, which are of great importance for this article. They have allowed to find Russian tradition, which has to be used to develop the doctrine of legal force of an administrative act, and the main foreign legal research on this subject could be compared with Russian thought and common features were discovered that could also be used to improve the Russian doctrine.

          As a result, the terms substantive and formal legal force should be returned to the Russian legal vocabulary, since they were used to describe legal force in our legal tradition. Interesting results can be obtained by comparing judgements and administrative acts, and the specificity of administrative acts will be emphasized. This way allows to apply some legal constructions characteristic of a judicial theory well developed in practice, including the “Roman basis” of the legal force of an administrative act. The division of administrative acts into void and voidable will make it possible to clarify ideas about their legal force, as well as the powers of authorities to amend or cancel such acts. The scope of administrative discretion when deciding questions of the validity of void and voidable acts will also vary.