“Uncertainties about the human mind loom large,” she wrote. “Even as some puzzles get resolved, others emerge. And those perennial gaps in knowledge intersect with differing opinions about how far, and in what ways, mental illness should excuse criminal conduct.”

The Supreme Court delivered a ruling in Kahler v. Kansas that could have widespread consequences for future criminal cases across the nation. In the 6–3 ruling, the justices declared the Constitution does not mandate states offer an insanity defense, according to The New York Times.

The case was taken up by nation’s highest court when James Kahler, the defendant, decided to appeal his conviction in the 2009 murders of his wife, two daughters, and their great-grandmother. The defense team for Kahler argued he suffered from a crippling depression that rendered him incapable of determining right from wrong.

In 1995, however, Kansas had effectively removed the statute permitting an insanity defense, except for when it comes to sentencing, potentially opening the door for lighter prison terms. In Kahler’s case, the Osage County District Court of Kansas’ 4th Judicial District issued a guilty verdict and sentenced him to death.

The Supreme Court heard oral arguments on Oct. 7 before issuing its ruling reaffirming the state’s decision on Monday. Justice Elena Kagan joined the five justices appointed by conservative presidents—Chief Justice John Roberts, Justices Clarence Thomas, Samuel A. Alito Jr., Neil M. Gorsuch, and Brett M. Kavanaugh—in voting in Kansas’ favor.

Letting the States Decide

“That choice is for Kansas to make — and, if it wishes, to remake and remake again as the future unfolds,” wrote Kagan for the majority opinion. “No insanity rule in this country’s heritage or history was ever so settled as to tie a state’s hands centuries later.”

Kahler’s petition to the Supreme Court centered on the due process clause and whether it permitted Topeka to “abolish the insanity defense,” Slate reported. In previous cases on due process, the court has traditionally taken a hands-off approach, stating in Snyder v. Massachusetts (1934) that a violation of due process can only occur if a law “offends some principle of justice so rooted in the traditions and conscience of our people as to be ranked as fundamental.”

As Carissa Byrne Hessick reported for Slate, the majority opinion acknowledged this with Kagan writing, “Kahler is right that for hundreds of years jurists and judges have recognized insanity (however defined) as relieving responsibility for a crime.”

However, the majority considered Kansas’ current statutes as sufficiently qualifying as an insanity defense. The two laws allow for defendants to plead for lighter sentencing due to mental incapacitation and as a trail defense in which the accused can argue they “as a result of mental disease or defect, lacked the culpable mental state required” to commit the crime in question. For all intents and purposes, Kansas does not recognize either laws as an insanity defense, however, and they cannot be used to shield a felony from the death penalty, as in Kahler’s case.

Kagan also opined on the current state of psychological conditions and how they influence verdicts, NPR reported.

“Uncertainties about the human mind loom large,” she wrote. “Even as some puzzles get resolved, others emerge. And those perennial gaps in knowledge intersect with differing opinions about how far, and in what ways, mental illness should excuse criminal conduct.” 

The decision on those matters is better left to individual states, Kagan added. 

Ending a ‘Deeply-Rooted’ Protection

Justice Stephen Breyer alongside Justices Ruth Bader Ginsburg and Sonia Sotomayor penned the dissenting opinion. 

He said the state “has not simply redefined the insanity defense. Rather, it has eliminated the core of a defense that has existed for centuries: that the defendant, due to mental illness, lacked the mental capacity necessary for his conduct to be considered morally blameworthy.”

“Few doctrines are as deeply rooted in our common-law heritage as the insanity defense,” he continued. “A defendant who, due to mental illness, lacks sufficient mental capacity to be held morally responsible for his actions cannot be found guilty of a crime. This principle remained embedded in the law even as social mores shifted and medical understandings of mental illness evolved.”

Kansas is one of only four states including Idaho, Montana, and Utah that have scrapped the insanity defense. All four states also permit the death penalty.

Now that the Supreme Court has ruled that states are not required to offer an insanity defense, it could set a precedent for other states to reference in future cases.

Monday’s decision, as well as the court’s ruling on two other cases, was announced online instead of from the bench due to the Covid-19 outbreak.