Christopher Slobogin (Vanderbilt University – School of Law) has posted Replacing the Special Defense of Insanity with Subjectively Defined Standard Defenses on SSRN. Here is the abstract:
On the assumption that the predominating guidepost of the criminal law is blameworthiness, this paper, an entry in the Criminal Law Conversations project, argues that the insanity defense is no longer needed. Instead, mental disorder should be relevant to criminal culpability only if it supports an excusing condition at the time of the offense that, under the subjective approach to criminal liability exemplified by the Model Penal Code, would be available to a person who is not mentally ill. The three most prominent such conditions would be: (1) a mistaken belief about circumstances that, had they occurred as the person believed, would amount to a legal justification; (2) a mistaken belief that conditions exist that amount to legally recognized duress; and (3) the absence of intent to commit crime (i.e., the lack of mens rea defined subjectively, in terms of what the defendant actually knew or was aware of). This "integrationist" approach eliminates the special defense of insanity while providing people with mental disability the same defenses available to everyone else.