Comprehensive review of factors participating in the appearance of disorders of arousal due to sleepwalking or polysomnography of an accused is discussed. The expert witness in these cases can inform all parties that there is absolutely no after-the-fact polysomnographic finding that could have any relevance as to whether the accused was sleepwalking at the time of event. Expert witness should become familiar with the concept of junk science in the court room. They must be aware of the guidelines for expert testimony formulated by a number of professional organizations. The expert witness should possess a current, valid, unrestricted license, must be a Diplomat of the American Board of Sleep Medicine, and must be familiar with the clinical practice of sleep medicine. Expert witnesses might better serve justice and the field if they could be appointed amicus curiae, meaning a court-appointed expert.