Mental Illness, Legal Culpability, & the Fourteenth Amendment: Why Due Process Allows States to Chose a Mens Rea Insanity Defense Over a M'Naghten Approach

Abstract

Does it violate Fourteenth Amendment due process to abolish the M’Naghten version of the insanity defense while providing in its place a right to introduce evidence of mental illness to negate mens rea? This Comment argues it does not.There is no constitutional right to the M’Naghten insanity defense. States may eliminate that defense if the state allows defendants a comparable defense such as a right to introduce evidence of mental illness to negate mens rea. States traditionally have the capacity to define crimes and defenses within the bounds of the Fourteenth Amendment. States may take the Mens Rea approach for the following reasons:First, no one formulation of the insanity defense is deeply rooted enough in history and tradition to raise it to the level of a fundamental right. In fact, the concept of mens rea central to the Mens Rea Model is actually older than the M’Naghten insanity defense. Second, limiting mental disease evidence to the negation of mens rea does not violate the concept of fundamental fairness. Under the Mens Rea Model defendants can introduce evidence of their mental illness as a defense to negate mental state, and they only need to raise a reasonable doubt to prevail, a much more favorable standard for defendants. Third, in light of the Supreme Court’s decision in Clark v. Arizona, which allowed a state to strictly limit the M’Naghten insanity defense and eliminate the Mens Rea defense, states should be able to do the reverse by eliminating M’Naghten and embracing the Mens Rea Model.