A variety of conceptually different proposals exist on the subject. Proposals to abolish mental disability as an independent defense have no insurmountable constitutional problems. However, proposals to disallow evidence of mental disability on the issue of guilt at all stages of the proceedings produce a serious constitutional issue. A constitutional issue also arises if the proposal is to remove mental disability as an independent defense and further to allow evidence of it in such a way as to eliminate a substantive element of mens rea: a sufficiently balanced mental state to render the knower culpable. The constitutionality of abolishing the insanity defense may hinge on the constitutionality of allowing legislatures to define the mental element of true crimes so as to exclude the requirement of culpability and blameworthiness. Whether they can do this will depend on whether such a definition would violate some principle grounded in the traditions and conscience of our society. Discussions of court decisions striking down statutes eliminating the insanity defense are included. A total of 36 footnotes are supplied.