Aim: This article aims to determine the standards of interaction of medical professionals, psychiatrists, and psychologists with participants in criminal proceedings during the implementation of various forms of use of special knowledge, as well as update their adherence in medical practice and criminal procedural activities. Materials and Methods: As empirical material, the decision of the ECHR, the practice of the Ukrainian courts, the results of scientific research by scientists, dedicated to the related subject of research, were used. In order to realize the set goal, the authors used a whole complex of general scientific and special methods of cognition, namely: system-structural method, method of generalization, dogmatic method, analysis and synthesis, methods of analysis of quantitative indicators, etc. Conclusions: The use of medical and psychiatric knowledge must be carried out in compliance with a number of legal principles. All participants in criminal proceedings are required to comply with them. The main criteria for the use of special knowledge include: the validity of the grounds for the implementation of certain forms, the impartiality and independence of the person entrusted with the examination or other form, the rule of law, the inadmissibility of disclosing the secret of the pre-trial investigation, the right to receive another independent opinion.