The Importance of Expert Opinion for Forming Moral Certainty of Parties to a Trial

Introduction: the issues of the use of special knowledge in criminal proceedings, its role and importance in proving criminal cases, despite the obvious demand for the use of such, do not cease to be relevant and widely discussed. This is due to the fact that this topic is multidimensional, which means there will always be a subject of research, unsolved problems and prospects for scientific research. The problems related to the significance of expert opinions in forming moral certainty of parties to a trial still remain in the shadow of significant and important topics. Purpose: to identify the factors influencing the expert opinion on forming moral certainty of parties to a trial. Methods: the dialectical, systemic and logical methods (general scientific) were used in the course of the study. Among the specific scientific research methods, the formal legal and generalization methods prevailed. Results: the formation of moral certainty is a complex process that depends not only on the personality of the expert, the quality of expert work, conclusions, but also on the subjective properties of parties to a trial, their professional training and erudition. That is why an expert should always take into account in their work the addressee of the evidence, i.e. those whom they should help in forming their moral certainty. Conclusions: the certainty in the correctness of the expert’s conclusions should be determined, first of all, by objective factors – the completeness and scientific validity of the conclusion, its clarity and obviousness, the correspondence of conclusions and answers to questions to other evidence, the expert’s deep special knowledge – and then subjective factors related to the personality of the expert.