Abstract
The article discusses the prohibition to substitute testimony of a witness and defendant’s explanations. The author presents the extent of the prohibition and exceptions therefrom. In particular, attention has been drawn to the issues connected with a refusal to testify and explain, as well as using written matter, including secret notes and official memoranda. The problems of questioning and interviewing an officer of the authority conducting the proceedings have been discussed. Important theses concerning the conditions for the functioning of this prohibition in criminal proceedings have been also formulated.