The presented article considers the essence and content of the most common defect in legal science— “legal gaps”. This study presents various scientific approaches to the definition of legal gaps. Considering various scientific approaches, the authors of this study formulated their original version of this concept considering its absence from the theory of penitentiary law. The study analyses the main conceptual approaches to the problem of the progressiveness of law in the historical context. The main features of legal gaps are named to become able to distinguish them from conflicts of law. The authors outlined a set of features indicating the presence of a legislative gap in a particular case and provided a scientifically ...