Despite contradictory testimony by prosecution psychiatrists, the jury found Hinckley not guilty by reason of insanity. In response to public outcry, Congress enacted the Insanity Defense Reform Act of 1984. This Act severely limits the availability and effectiveness of the insanity defense. Part of the act, Federal Rule of Evidence 704(b) prohibits expert witnesses from stating ultimate conclusions on the mental health of criminal defendants. By limiting mental health testimony by experts, this rule prejudices criminal defendants, creates confusion in Federal courts, and resurrects the defunct and legally unsound ultimate issue rule. It is argued that this provision should be repealed and that the legitimate dangers posed by expert testimony could be eliminated by proper implementation of Rule 702. Under Rule 702, courts should require experts to explain the underlying premise of the expert's opinion and should exclude testimony couched in terms that the ordinary jury would not understand. Inadequately explained testimony should be excluded as unhelpful to the jury. Further, courts should not allow witnesses to determine legal standards, and testimony that states or implies applicable legal standards should be excluded. Finally, courts should not restrict testimony merely because it bears on an ultimate issue. All relevant testimony should be admitted if it assists the triers of fact. Jurors must be trusted to separate convincing from unconvincing testimony. 156 footnotes.