Bejdová, ZuzanaLacyková, Kristína2026-04-242026-04-2420262730-0641https://doi.org/10.5219/legestic.14https://repo.umb.sk/handle/123456789/1416In: Legestic. Nitrianske Hrnčiarovce : HACCP Consulting, 2026. ISSN 2730-0641. Vol. 3 (2026), pp. 11-21.The cooperating person represents a fully legitimate procedural institute within the Slovak criminal justice system; however, testimony obtained through cooperation is inherently burdened by the individual’s personal criminal-law interest arising from the expectation of procedural or substantive benefits. This structural characteristic raises serious concerns regarding the evidentiary strength, epistemic value, and permissible limits of reliance on such testimony in criminal proceedings. The article examines the conceptual distinction between credibility and truthfulness as fundamental normative attributes of testimony provided by cooperating persons. While credibility traditionally dominates judicial assessment, it does not necessarily guarantee correspondence with objective reality, particularly where testimony is motivated by anticipated advantages. The authors analyse recent legislative developments introduced by Act No. 416/2025 Coll., which amended the Code of Criminal Procedure by transforming truthfulness from a predominantly epistemic criterion into an explicit normative condition governing the admissibility of cooperation-based evidence. Through doctrinal legal analysis, normative interpretation of statutory provisions, and examination of the case-law of the European Court of Human Rights, the article evaluates whether the Slovak legal framework adequately addresses the evidentiary risks inherent in motivated testimony. Particular attention is devoted to the requirement of independent corroboration and to the interaction between truthfulness as a threshold condition of admissibility and credibility as a subsequent evaluative criterion. The authors conclude that the legislative emphasis on truthfulness constitutes a necessary corrective to the traditional reliance on credibility alone and strengthens safeguards against convictions based on unverified or distorted testimony. At the same time, the article assesses the compatibility of the national regulation with the requirements of a fair trial under Article 6(1) of the Convention for the Protection of Human Rights and Fundamental Freedoms and contributes to the broader discourse on the evidentiary limits of cooperation-based testimony in criminal proceedings.enCC BY-NC-ND Creative Commons Attribution-NonCommercial-NoDerivatives 4.0. Internationalinfo:eu-repo/semantics/openAccessspolupracujúce osobycooperating personskredibilitaspravodlivé procesyfair trialsArticle