Introduction: the paper analyzes scientific data related to the definition of the phenomenon “lengthy prison term” and demonstrates a relative and conditional nature of this phenomenon. Available scientific research findings in this area suggest that the duration of serving a sentence is an exclusively subjective measure for various criminals. Goal: to identify the impact of the length of prison sentences on convicts in the context of their reformation. Methods: we use general scientific research methods (analysis, synthesis, comparison, generalization). The work is based on the results derived from the analysis of relevant foreign and domestic studies. Results: by analyzing the influence of specific features inherent in correctional institutions, we reveal the following inconsistency: custodial sentences and lengthy prison terms contribute to the adaptation of convicts to prison conditions, development of negative changes in their personality, destructive conduct, etc. In addition, prolonged stay in a correctional institution reduces the impact of major means of reformation such as prison regime, educational work, and socially useful work. Conclusions: when determining the length of prison term, it is necessary to proceed not so much from the nature and degree of public danger of the act, but from individual features of the criminal’s personality, their social environment, and the motive for the crime committed. It is necessary to abandon the quantitative approach to determining the mea sure of punishment expressed in the length of the prison term.
Key words: lengthy prison term; serving a sentence; correctional institutions; crime; convicts; reformation; punishment; penal system of the Russian Federation; isolation conditions.