Systemic Convention Compliance Deficit in Ukrainian Criminal Procedure: Criteria for Recurrent and Structural Violations in the European Convention on Human Rights Case-Law

The article develops a criminal-procedure concept of a systemic Convention compliance deficit and establishes criteria for distinguishing individual, recurrent, structural and systemic violations of the European Convention on Human Rights. The empirical basis comprises 18 judgments delivered by the European Court of Human Rights against Ukraine between 2004 and 2025, together with official materials of the Committee of Ministers and the Department for the Execution of Judgments. The study combines formal legal, comparative, systemic-structural, functional and diachronic methods with case-law analysis, clustering of legal positions, causal analysis and assessment of judgment execution under Article 46. The number of judgments or applications is shown not to be a sufficient criterion of systemic character. The decisive factors are a common root cause, temporal persistence, normative or institutional embeddedness, the capacity to affect a significant or indeterminate category of persons, the inadequacy of domestic remedies and the need for general measures. A systemic Convention compliance deficit is defined as a persistent multi-level failure of legislation, institutional organisation, procedural practice, remedial mechanisms and judgment-execution arrangements to comply with Convention standards. The article develops a nine-factor diagnostic test, identifies five principal clusters, substantiates a five-level model comprising normative, institutional, operational, remedial and execution-related levels, and reconstructs the cycle through which the deficit is reproduced. Particular attention is paid to the State’s retention of an unlawfully obtained procedural advantage. Legislative, institutional, judicial, prosecutorial and execution-related measures are proposed, including a National Convention Risk Matrix for criminal proceedings.