A description of the existing law on the insanity defense as expressed in court rulings and statutes focuses on abolition of the insanity defense, the definition of insanity, the allocation of the burden of proof, the limits of expert testimony, the verdicts available to judges and juries, and the proper disposition of insanity acquittees. Discussion is also devoted to organization and analysis of these issues, so policymakers can derive some preliminary directions for public policy. the intent of the discussion is to encourage cautious inquiry before undertaking legislative reform and provide information for policymakers in those jurisdictions in which legislatures may have rushed prematurely toward reform. Overall, it is concluded that the insanity defense, as an independent, exculpatory doctrine, has survived the latest attack. Also, early signals from Michigan, Indiana, Illinois, and Connecticut appear to indicate that the 'guilty but mentally ill' plea may not be living up to its promise as a viable alternative to the perceived difficulties with the insanity defense. Public policymakers, scholars, and the public at large seem to be in accord in their preference for special dispositional schemes that ensure adequate protection for society as well as provide secure treatment and care. The proper wording of the insanity defense is likely to continue to receive the attention of legal scholars, with no consensus in sight. A general recommendation is that any changes in the insanity defense be based not on anecdotal or conjectural evidence but on direct experience and the result of experimentation with various alternatives. A bibliography contains about 140 listings, and a subject index is provided.