“Trance and Possession” is clasified as dissociative disorder in International Classification of Disorders (ICD-10) and Diagnostic and Statistical Manual of Mental Disorders (DSM IV/ V). “Trance and Possession” could be qualified as the “other mental disturbance” on the ground of the Art. 31 of the Polish Penal Code. The perpetrator shall not commit an offence, if at the time of the commission of a prohibited act, was incapable of recognising its significance or controlling his conduct because of the trance and possession disorder. If at the time of the commission of an offence the ability to recognise the significance of the act or to control one’s conduct was diminished to a significant extent, the court may apply an extraordinary mitigation of the penalty. The court could hear as forensic experts psychiatrists, a psychologist, as well as specialists in anthropology, ethnography or religious studies.