Richard Bonnie on the Need for a Constitutional Right to the Insanity Defense


UVA Law Professor Richard Bonnie co-authored a brief filed with the U.S. Supreme Court that says criminal defendants should have the explicit right to an affirmative defense of legal insanity.

July 20, 2012

Four states — Idaho, Kansas, Montana and Utah — do not allow criminal defendants to claim that they were not responsible for their actions on the grounds of insanity.

In a brief filed with the U.S. Supreme Court, a number of law professors argue that the state bans on the insanity defense are unconstitutional. The brief — written by Richard Bonnie of the University of Virginia and Stephen Morse of the University of Pennsylvania and signed by 50 additional law professors — urges the court to take up a case out of Idaho in which a defendant with paranoid schizophrenia killed two people and wounded a third, but was barred from mounting a defense on the basis of insanity.

Bonnie, a UVA professor of law, medicine and public policy and director of UVA's Institute of Law, Psychiatry and Public Policy, explained why he believes the Supreme Court should establish a constitutional right to the insanity defense.

In the brief, you argue that the due process clause should be explicitly recognized as guaranteeing criminal defendants the right to an affirmative defense of legal insanity. Can you explain how you arrived at this conclusion?

There are essentially two related grounds for this conclusion, historical and moral. The basic principle reflected in the insanity defense is that a person is not criminally responsible if, because of a severe mental illness, he or she lacked rational understanding of the wrongfulness of the offending conduct. This principle has deep historical roots in the common law, and is famously reflected in the rules announced by the House of Lords in M'Naghten's Case in 1843. All states except four (as well as the federal law) recognize this basic principle, which is grounded in a widely shared moral intuition that blaming and punishing a severely ill person is morally wrong.

The states that don't allow defendants to plead insanity have other mechanisms to handle defendants who are arguably mentally ill. Can you describe how they work?

The four states, including Idaho, allow evidence of mental illness to be introduced if and only if the evidence would show that the defendant did not have the "intent" required in the definition of the offense. However, the morally significant symptoms of severe mental illness rarely are relevant to "intent" and that is why the common law courts have recognized an affirmative defense for insanity for hundreds of years.

What are the primary arguments against having a constitutional right to the insanity defense? In what ways do you think these objections are flawed?

The argument in the context of this case is that the Supreme Court should leave this matter to state legislatures and courts. The brief does point out that the policy arguments against the defense are weak. The main policy argument made by opponents of the insanity defense is that the public would be safer without it because these dangerous, mentally ill people would be in prison. But quite the reverse is probably true. Public safety is probably better assured by committing the insanity acquittee to an indeterminate period of confinement and treatment in a secure psychiatric facility. Modern statutes provide a very tight system of oversight and supervision for these patients when they are released into the community.

If the Supreme Court were to recognize a constitutional right to the insanity defense, what would be some of the real-world implications?

Compared to just about any other Supreme Court decision, the immediate impact on administration of the law would be modest: The four states that have abolished the defense would have to re-enact it. However, a decision constitutionalizing the insanity defense would contribute significantly to the development of constitutional principles bearing on substantive criminal law.

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