Persons dedicated to public safety as well as the rights of the defendant take contrary positions on this issue. Those taking a prosecution approach want to exclude evidence of mental illness. Defense attorneys, some treatment-oriented mental health professionals, and others with similar interests want such evidence admitted. Beyond this there is a divergence of opinion on whether it is constitutional to preclude such evidence. In this controversy, there are a number of relevant issues in need of clarification. Tightening or abolishing the insanity defense does not preclude the use of extensive mental disorder testimony and evidence on responsibility issues in criminal cases. Federal law, American Bar Association standards, and legislation in many jurisdictions appear to leave the mens rea route for avoiding the insanity defense wide open. Further, confusion exists regarding the interpretation of the mens rea model: it may be given a strict interpretation that admits only evidence that the defendant did not entertain the requisite mental state; or a diminished capacity interpretation. Finally, the controversy highlights areas of fundamental problems between mental health professionals and the legal community. 204 footnotes.