The paper analyzes the issues of presenting a specialist's opinion in criminal proceedings, the problems of introducing a specialist into the judicial process on the initiative of a defender; criticizes the refusal of the Plenum of the Supreme Court of the Russian Federation from using a specialist's opinion to evaluate an expert's opinion; examines a new incorrect judicial practice of refusing admission to the process of specialists who had not previously participated in a criminal case. It is proposed to issue a separate resolution of the Plenum of the Supreme Court of the Russian Federation on the participation of specialists in criminal proceedings.