Implementation problems in criminal procedure the principles of equality and adversarial (for example, the possibility of filing by the defense of expert's opinion)

Background: The European criminal law system declares principles of competition and equality of parties as fundamental to ensure respect for human rights and fundamental freedoms. The domestic legal system also contains these concepts, but only the principle of competition, which includes equality, is declared as a fundamental principle. Such a seemingly insignificant difference in systems causes difficulties in implementing these principles in criminal proceedings, which is shown by the example of using special knowledge in the form of expert opinion and interrogation, and those few tools for the defense that can be used for qualified opposition by the prosecution, which builds its system of evidence on the expert’s conclusion. Vividly, implementation contradictions in the criminal process principles of equality and competition occur with the use of one of the parties (mostly by the defense) specialized knowledge in the form of imprisonment and interrogation specialist. Aims: This study aimed to analyze the problematic issues that arise in this case. Conclusion: Results of the study show the need for practical development and greater legal significance to the institution of participation of a specialist in criminal proceedings, both directly and separately through a written opinion, which meets not only the principles of modern improvement of the implementation of constitutional guarantees for justice, court access, and obtaining professional legal assistance, but also the provisions on the right to a fair trial, provided for in art. Six conventions for the protection of human rights and fundamental freedoms ETS N 005 (Rome, 4 November 1950) are ratified by the Russian Federation on March 30, 1998.