The Institution of International Legal Assistance in Criminal Matters in the National Legal System

The contemporary development of transboundary criminality, the digitalization of criminal procedure, and the expansion of international cooperation highlight the need to clarify the theoretical and legal nature of the norms governing international legal assistance in criminal matters. Legal scholarship continues to exhibit conceptual inconsistency regarding their branch affiliation: alongside the approach that treats these norms as part of criminal procedure law, other views propose their classification as an inter‑branch construct or even as an emerging sub‑branch. This lack of doctrinal clarity hinders both theoretical systematization and practical application, particularly in the context of ongoing codification efforts in procedural legislation. The aim of this study is to provide a comprehensive justification for classifying international legal assistance in criminal matters as an institute of criminal procedure law. To this end, the research examines the criteria of a legal institute as applied to this body of norms, compares the characteristics of an institute, a sub‑branch, and an inter‑branch formation, analyses the internal structure of the relevant regulatory complex with identification of its sub‑institutes, and clarifies the methodological foundations for its classification. The methodological framework of the study encompasses general scientific methods of analysis and synthesis, the formal legal method, comparative legal analysis, and a systems‑based approach. Additionally, the organisational and systemic model of A. Bogdanov (tectology) is employed to reveal the mechanisms of formation, evolution, and transformation of legal institutes. The findings confirm that the norms governing international legal assistance in criminal matters possess all the features of a legal institute, are functionally integrated into the system of criminal procedure law, and do not constitute either a sub‑branch or an inter‑branch construct. The structure of the institute includes several sub‑institutes that develop according to an internally coherent logic and ensure the systemic nature of legal regulation. A theoretically grounded recognition of the institutional character of international legal assistance contributes to clarifying the conceptual framework, improving legislation, and fostering a more consistent organization of the criminal justice process.