The article presents a comprehensive analysis of the legal consequences of abuse of subjective rights in the field of substantive law. It is substantiated that the abuse of rights, despite its external compliance with formal legal provisions, contradicts the general principles of the legal system, disrupts the balance of rights and interests of the parties, and therefore requires appropriate legal response. A differentiation of legal consequences is proposed, depending on the nature of conduct - either as a delictual act subject to liability, or as conduct that, while formally lawful, constitutes bad faith in the exercise of a permitted right. Two approaches to understanding the legal nature of abuse are distinguished: first, as an autonomous legal phenomenon occupying an intermediate position between lawful conduct and legal offense; and second, as a type of offense with all the characteristics and legal consequences typical of a violation. Special attention is given to the provisions of the Civil Code of Ukraine that provide for specific legal responses to bad-faith behavior - such as invalidation of a transaction, denial of legal protection, or obligation to cease the violation. The article also analyzes cases where abuse of subjective rights is recognized as a legal offense in the public law sphere, namely in administrative and criminal relations, with the application of relevant sanctions. An original systematization of legal measures countering the abuse of rights in substantive law is proposed, structured along four dimensions: functional purpose (preventive, restorative, obligational, punitive), subject of legal impact (property-related and non-property-related), procedural form of implementation (judicial and extrajudicial), and initiating subject (court or interested party). It is emphasized that the legal consequences of abuse are not limited to punitive sanctions but also fulfill regulatory and preventive functions, contributing to the reinforcement of good faith, fairness, and legal certainty as foundational elements of the legal order. The presented findings support the conclusion that the legal nature of abuse of rights in the substantive sphere encompasses both a delictual dimension -characteristic of classical offenses - and a specific form of deviation from good-faith behavior, which may not always involve a direct violation of a legal norm but nevertheless requires adequate legal reaction. This, in turn, calls for further theoretical and legal reflection and the development of clear criteria for the legitimate exercise of rights in modern legal conditions. At the same time, the issue of procedural abuses - such as manipulation of procedural rights and instruments-remains pressing, as it may pose an equally serious threat to the rule of law and the effectiveness of justice.
V. P. Ivanov (Thu,) studied this question.