
This author deals with the issues of the use of private expertise (the so-called private opinion) by advocates and legal advisers during criminal proceedings. Such possibility results from the wording of Article 393§3 of the Code of Criminal Procedure, which states that any private documents create outside criminal proceedings, in particular statements, publications, letters, and notes may be read out during the trial. This provision does not directly indicate the possibility of using private expertise, but such possibility is a consequence of the fact that private opinions are private documents. The said provision was introduced by the Act of 27 September 2013 amending the Act - Code of Criminal Procedure and certain other acts, which entered into force on July 1, 2015, and therefore the possibility of using private expertise in criminal proceedings has been functioning for over four years. This period allows doing empirical research on the use of expertise by advocates and legal advisers. The author presents the general attitude of advocates and legal advisers to the introduced possibility of using private expertise during criminal proceedings, as well as its conditions and obstacles.