On March 23, 2020, in Kahler v. Kansas, the U.S. Supreme Court ruled against Kansas death row prisoner James Kahler, who was convicted of killing his estranged wife, her grandmother, and the couple’s two daughters. The Court had granted certiorari after Mr. Kahler filed a petition asking the Court to address whether the Eighth and Fourteenth Amendments permit a state to abolish the insanity defense. The Court held oral arguments in October 2019. In its ruling, the Court held that due process does not require Kansas to adopt any specific insanity test, including a test that turns on a defendant’s ability to recognize that his crime was morally wrong.
As the Project previously reported, Kansas amended its criminal code in 1995, abolishing its mental incapacity test for the insanity defense. Though Mr. Kahler’s trial featured expert testimony about his mental illness at the time of the shooting, he was unable to plead not guilty by reason of insanity. In most states, a defendant is able to use insanity as an affirmative defense by showing that even if he committed the crime, he did not know right from wrong due to his mental illness and therefore was not culpable. Under Kansas law, however, the moral capacity of the defendant is irrelevant, and unlike in many other states, a Kansas defendant cannot be wholly exonerated on the ground that his illness prevented him from recognizing his criminal act as morally wrong. For Mr. Kahler, and defendants like him, the only option is to argue that they lacked the required mental state for the crime—here, the intent to kill. Kansas does not recognize any additional way that mental illness can produce an acquittal, but defendants can present evidence of mental illness after a conviction to justify a lessened punishment at the sentencing phase.
In Kahler, Justice Kagan authored an opinion joined by five other justices rejecting Mr. Kahler’s assertion that Kansas had effectively eliminated the insanity defense. The Court held that a state’s failure to allow a mentally ill defendant to raise the moral incapacity approach to the insanity defense is not the equivalent of abolishing the insanity defense, nor does it violate the Constitution. In reaching this conclusion, the Court first outlined the various insanity defenses used by states throughout the country. While there is no universal test for the insanity defense, many states and the federal government have adopted the M’Naghten rule. The M’Naghten rule allows a defendant to succeed on an insanity defense in either of two circumstances: if at the time of the crime, mental illness rendered the defendant incapable of knowing what he was doing or mental illness rendered the defendant incapable of understanding that what he was doing was wrong. The test separates the concepts of cognitive incapacity and moral/legal incapacity, so that each form of incapacity serves as a stand-alone insanity defense. Kansas has retained only the cognitive incapacity prong of the M’Naghten rule.
The Court explained that Mr. Kahler faced a high bar in proving that the Kansas law violated his constitutional right to due process. According to the Court, a state rule about criminal liability violates due process only if it “offends some principle of justice so rooted in the traditions and conscience [of] our people as to be ranked as fundamental.” To make such a determination, courts must ask whether a rule is “so entrenched in the central values of our legal system” so that a state could never choose an alternative rule. In applying this standard, the Court relied on “historical practice” as its primary guide, looking at common-law authorities as well as English and American judicial decisions. The Court agreed with Mr. Kahler to the extent that “[f]or hundreds of years, jurists and judges have recognized that insanity can relieve criminal responsibility.” However, the majority disagreed with Mr. Kahler’s argument that the Kansas law effectively deprived defendants from asserting an insanity defense, relying on two aspects of the law to support its conclusion that Kansas has not abolished the insanity defense: Kansas law retains a cognitive incapacity test; and defendants are still able to introduce evidence of mental illness as a mitigating factor during sentencing, to either convince the jury to vote for a lesser sentence or convince the judge to replace imprisonment with commitment to a mental health facility.
Because the Court concluded that Kansas had not abolished the insanity defense, Mr. Kahler could only prevail by showing that due process requires states to adopt a specific insanity test and, in his case, the mental incapacity test. However, the Court specified that decisions about criminal liability and mental illness are precisely the type of determinations left to the states. The Court referenced its prior decision in Powell v. Texas, which concluded that the scope of criminal responsibility is animated by complex and shifting ideas that are best left to the states to evaluate and reevaluate over time. The court noted, “early common law cases and commentaries reveal no settled consensus favoring Mr. Kahler’s preferred mental incapacity rule” and various state approaches “show that no single version of the insanity defense has become so ingrained in American law as to rank as ‘fundamental.’” The Court also noted that it had twice declined to adopt any specific version of the insanity defense as a constitutional baseline in Leland v. Oregon and Clark v. Arizona.
The dissenting opinion, authored by Justice Breyer and joined by Justices Ginsburg and Sotomayor, asserted that the Kansas scheme violated Mr. Kahler’s constitutional right to due process. Justice Breyer accepted the basic premise of the majority’s approach that “the Constitution gives the States broad leeway to define state crimes and criminal procedures, including leeway to provide different definitions and standards related to the defense of insanity.” However, in Justice Breyer’s view, Kansas had gone beyond just redefining the insanity defense, and instead “eliminated the core of a defense that has existed for centuries.” According to Justice Breyer, there is a clear insanity defense rule based on common law authorities: defendants cannot be held criminally liable if, “due to mental illness, they lacked the mental capacity necessary for their conduct to be considered morally blameworthy.” Justice Breyer explained that while M’Naghten is the most prominent expression of this principle, it is not the exclusive one, highlighting that 45 states, the federal government, and the District of Columbia all recognize some kind of insanity defense that considers whether the defendant is morally responsible for his actions.
The dissent rejected the State’s explanation that it had “not abolished the insanity defense or any significant part of it” and instead had “simply moved the stage at which a defendant can present the full range of mental-capacity evidence to sentencing.” Instead, Justice Breyer stressed that tradition “demands that an insane defendant should not be found guilty in the first place.” Justice Breyer used an example to demonstrate the importance of his position—which he also referenced during oral arguments—where two defendants are each on trial for shooting and killing another person. In the first case, because of severe mental illness, the defendant believed that he was killing a dog. In the second case, as a result of severe mental illness, the defendant believed that a dog had told him to kill the person. Under an insanity defense that contains both the cognitive and mental incapacity prongs, as traditionally understood, neither defendant would be found guilty. However, under the Kansas scheme, the second defendant can be convicted, regardless of his mental illness, because he would have intended to kill the person, despite believing a dog ordered him to do so.
Critics of the decision argue that the Kansas law does not actually provide defendants with a cognizable defense. Rather, the Kansas law restates the burden that prosecutors have always had: to prove that the defendant acted with requisite intent.