An increasing reliance on mental health knowledge to help decide legal issues is being accompanied by a growing skepticism about the use of this 'expertise.' The mental health professions have demonstrated limited clinical abilities to determine a juvenile's amenability to treatment, to rehabilitate juvenile offenders, and to determine the best interests of children in abuse/neglect and custody dispositions. The limits of mental health expertise in juvenile and family law include the limits inherent in scientific methods, such as use of esoteric jargon in the courtroom and the inability to describe scientific methods to laypeople. Legal responses to the limits of expert knowledge in adult criminal and civil courts include the 'general acceptance' and 'reasonable and customary reliance' standards. The utility of mental health expertise is also limited to some extent by the legal method used to introduce it; i.e., the 'battle of the experts.' Tolerance for the limits of mental health expertise varies by legal context and becomes essentially an ethical issue to be resolved by the legal system. References.