Mental health legal reports and testimony are typically inadequate in relating technical mental health data and inferences to trial issues. When clinical material is presented without the expert's reasoned application of the material to trial issues, then the triers have no basis for understanding what specific material the professional used in arriving at the final mental health legal opinion, why the witness selected the material presented, and the meaning it has for the legal issue. To improve the value of their legal contributions, mental health professionals must explore the social policies and legal issues of each case; e.g., in applying clinical material to the issue of criminal responsibility, the expert witness must understand the legal test of criminal insanity in the trial jurisdiction. In rendering opinions based on legal doctrines, the expert witness must refrain from offering opinions based in personal beliefs about the criminal culpability of mentally ill persons.