An analysis of the concept of competency considers the problem of treating those who are incurably incompetent, focusing on the tension between a defendant's right to be competent to stand trial and society's need to ensure that dangerous defendants are not released. The article argues that a defendant likely to be permanently incompetent to stand trial should have the insanity defense imposed so as to resolve the case with a disposition. The review of the insanity defense outlines the historical development of Washington State's M'Naghten standard and compares it to standards used in other jurisdictions. The article concludes that Washington State's insanity law, based on a strict construction of M'Naghten, makes sense from a psychiatric perspective and should not be abandoned. An analysis of the diminished capacity defense, a recently attractive alternative to the insanity defense, compares the experts' roles in insanity cases and diminished capacity cases. The article proposes that the diminished capacity defense be abolished, because mental health experts lack the expertise to determine whether a defendant was so incapacitated as to have been unable to form 'intent' or 'knowledge.' 277 footnotes.