OBJECTIVE: The aim: The aim of this work is a legal analysis of the mental health presumption and its application by judges in assessing the report of the FPE; formulation of scientifically substantiated proposals for determining the criteria for the judge's assessment of the FPE report in refuting the presumption of mental health context. PATIENTS AND METHODS: Materials and methods: The basis for the article was the results of scientific research published by representatives of different states regarding the criteria for assessing the expert's opinion as a procedural source of evidence; legislation (in the field of psychiatric care and criminal justice) of a number of European and Asian states and its implementation xperience; results of the survey of 88 judges conducted by the authors (judges of local courts of Ukraine, the survey was conducted in 2020) on key issues of ensuring the participation of a person suffering from a mental disorder in a court hearing. In this research, a complex of general and special scientific methods of cognition was used (comparative legal method, systemic-structural method, generalization method, method of analysis and synthesis, method of sociological research, method of expert assessments, etc.). RESULTS: Results: According to the results of the research: a) it is stated that the presumption of a person's mental health is a common European standard, regardless of the normative consolidation at the level of domestic legislation; b) it is proved that the effectiveness of the judge's use of the presumption of mental health in criminal proceedings directly correlates with his or her competent assessment of the FPE report and the providing appropriate argumentation in a court hearing; c) the factors that allow the judge to correctly assess the report of the FPE and put it in the basis of decision-making (that is, to refute the presumption of mental health of a person), or, on the contrary, to deny it (stating that the presumption of mental health has not been abolished). CONCLUSION: Conclusions: As a principle of modern psychiatry, the presumption of mental health is directly correlated with the FPE report, based on which it can be refuted. This determines the special importance of a competent assessment of this procedural source of evidence, the need for the judge to take into account several factors and to provide appropriate argumentation in the court hearing.