In this article, the main concepts, the legal basis for the participation of an expert, the the characteristics of the participation of an expert in economic courts, the concept of an expert on the basis of sources of law, opinions and comments of domestic and foreign legal scholars about the person administering justice - an expert, the probative force of an expert's opinion , the conclusions of well-known scientists-processors, the necessary requirements for an expert, the issues of obtaining remuneration for the participation of an expert in court, the reasons for his refusal to participate in a court session. the consideration of the case, its responsibility, domestic and foreign experience, proposals and recommendations for improving the legislation took place.