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Supreme Court rules that states may define the insanity defense

On behalf of Dolan + Zimmerman LLP April 5, 2021

On Thanksgiving 2009, James K. killed his wife and two teen daughters. In his defense, the man had been under substantial stress. Several months earlier, his wife had left him and taken the children with her. Also that year, James had lost his job and been forced to move in with his parents.

Did these events rob James of the ability to fully understand the wrongfulness of his actions? In the past, it would have been up to a jury to decide. But for James, the chance to bring that defense was outlawed by a 1996 Kansas law that restricts the insanity defense.

Traditionally, there have been two ways to make an insanity defense. You could show that a mental illness or defect either:

  • Caused the defendant to be unable to conform his actions to the law
  • Caused the defendant to be unable to understand that his actions were wrong

Kansas’s law eliminated this second construction, leaving mental illness to be considered only as a mitigating condition. James argued that he was being denied access to a traditional defense and that this violated his due process rights.

James, who was convicted of murder and sentenced to death, appealed to the U.S. Supreme Court after the Kansas courts turned down his pleas.

Can a state simply eliminate a traditional defense?

The Supreme Court recognized that denying James a chance to bring an insanity defense might violate due process if it “offends some principle of justice so rooted in the traditions and conscience of our people, as to be ranked as fundamental.”

Does eliminating one of the traditional insanity defenses offend a deeply-rooted principle of justice? Ultimately, the justices said no, it does not.

Writing for the 6-3 majority, Justice Elena Kagan explained that formulating a fair and just insanity defense involves psychology, criminal justice, free will and responsibility.

“It is a project demanding hard choices among values, in a context replete with uncertainty, even at a single moment in time. And it is a project, if any is, that should be open to revision over time, as new medical knowledge emerges and as legal and moral norms evolve,” wrote Justice Kagan.

“Which is all to say that it is a project for state governance, not constitutional law.”

She explained that the precise formulation of the insanity defense has changed over time as cognitive science has improved. “No insanity rule in this country’s heritage or history was ever so settled as to tie a state’s hands centuries later.”

In other words, this is a constantly changing area of the law. That makes it ideal for states to decide.