The authors discuss the problems of forensic-psychiatric expert examination related to the responsibility of persons suffering from different mental disorders. In addition to the assessment of the clinical picture of a mental disease, it is necessary to take into consideration (as fully as possible) the genesis and character of the committed socially dangerous action (SDA). For this purpose it is recommended that the concept of the psychopathological mechanisms of SDA worded by the authors and their classification be made use of. The establishment in a mental patient of one of the distinguished mechanisms of SDA allows the differentiation of the intellectual and volitional signs of the judicial (psychological) criterion and scientific basing of the conclusion as to the patient's irresponsibility.