One of the pressing problems of Forensic Science is to define criteria for assessing Personality Disorders (PD)with a view of Article 21 of the Russian Federation Criminal Code. Forty cases with paranoid, schizoid and mixed types of Personality Disorders were studied for the purpose of passing judgment on their inability, during the acts of aggression, to be recognize the true character and the societal danger of their actions and to control themselves.

Half of the cases demonstrated situational development, with marked exacerbation of suspiciousness and a bend towards forming extremely valuable ideas, followed by pronounced depressive conditions, persistent adjustment disorders, and impaired ability for critical judgment and prognosis. Twenty-five per cent of the cases showed pathological (constitutional) personality development. Delirious ideas of jealousy and anger (litigiousness) were systemic, deeply and heavily loaded emotionally, they developed in the “self-development” mode, with loss of content of the emotion and with psychogenic reactions. In 17.5% of cases our conclusions were based on the assertion that during the criminal act, “acute reaction to stress” was experienced, with deep emotional involvement, impaired consciousness, loss of ability to adequately assess the obtaining situation, and general disorientation.

Thus, the main prerequisite for inability to appreciate the factual character and societal danger of one's actions or to control them is the statement of reactions of psychotic level, or of pathological development with the presence of pathologically overvalued or maniac ideas of interpretative nature, transforming into a paranoid system.