The article is assigned to the procedural significance of the expert’s activity, under the hour of the examination in criminal proceedings for the most reasonable lines. The peculiarities of the status of an expert in criminal prosecution, and its role in the activities of parties in criminal prosecution are the main tasks of criminal prosecution. The relevance of the study is determined by the fact that, in accordance with part 1 of article 6 of the European Convention on Human Rights, everyone has the right to a fair and public hearing of his case within a reasonable time by an independent and impartial court established by law, which will resolve the dispute regarding his rights and obligations of a civil nature or establish the merits of any criminal charge brought against him. The general requirements of justice contained in Article 6 apply to all criminal proceedings regardless of the type of offence being considered.
Injecting the effectiveness of the activities of the expert visas on the development of reasonable lines in the criminal investigation. The search for innovative sources to improve the quality of this work, and the use of the achievements of science and technology, should go hand in hand with the introduction of new methods of conducting expert research within the framework of criminal proceedings, which would affect the provision of procedural terms, the effectiveness of investigative (search) actions and would exclude delays and abuse by right.
Key words: expert, expert opinion, intelligent lines, parties to criminal proceedings, efficiency of pre-trial investigation.