Kahler v. Kansas

LII note: the oral arguments in Kahler v. Kansas are now available from Oyez. The U.S. Supreme Court has now decided Kahler v. Kansas .


Does abolishing the insanity defense violate the Eighth or Fourteenth Amendments?

Oral argument: 
October 7, 2019
Court below: 

This case asks the Supreme Court to balance states’ rights to write their own criminal code with individual rights under the Due Process Clause and the Eighth Amendment. The statute at issue, Kan. Stat. Ann. § 22-3220, abolished the traditional right-and-wrong test for the insanity defense in favor of a mens rea approach to insanity. Kahler argues that history and tradition demonstrate that the right-and-wrong test for insanity is a fundamental right under the Due Process Clause. He also contends that disallowing this test essentially abolishes the insanity defense, which is cruel and unusual because it punishes individuals who lack moral culpability for their crimes. Kansas counters that the right-and-wrong test for insanity is not a fundamental right because it is not deeply entrenched in tradition, and that disallowing the defense would not have been deemed cruel and unusual when the Eighth Amendment was adopted. The outcome of this case has heavy implications for states’ authority over their own criminal code, just punishment, and protecting individuals who lack moral culpability.

Questions as Framed for the Court by the Parties 

Whether the Eighth and Fourteenth Amendments permit a state to abolish the insanity defense.


James Kahler and his wife, Karen, had two daughters and one son. During the summer of 2008, Karen began a sexual relationship with another female, and their marriage soon began to fall apart. Ultimately, Karen filed for divorce in January 2009 and moved out with their kids that Spring. Kahler did not handle the divorce well, and it affected his life, both professionally and personally. As a result, in August 2009, he was fired from his job and he moved back home to live with his parents on their ranch near Meridian, Kansas.

Later that year, the rest of Kahler’s family was spending Thanksgiving in Burlingame, Kansas at Karen’s grandmother’s house. Kahler unexpectedly arrived at the house and shot and killed Karen’s grandmother, Karen, and his two daughters. Kahler managed to escape, but the police arrested him the next day. Kahler was charged with one count of capital murder, or alternatively, four counts of first-degree murder. He was also charged with one count of aggravated burglary.

At his trial, Kahler admitted that he shot the four victims, but argued that he did not have the requisite intent and premeditation to commit capital murder because he suffered from severe depression at the time of the shooting. The jury disagreed and found Kahler guilty of capital murder. The same jury recommended the death sentence.

On appeal to the Kansas Supreme Court, Kahler raised ten issues, including an argument that K.S.A. 22-3220 was unconstitutional because it did not provide him an opportunity to present an insanity defense. The statute, implemented in 1996, abandoned the traditional M’Naghten approach to the insanity defense, which allows defendants to present evidence that, due to a mental disease or defect, they did not realize that what they were doing was wrong. Kansas adopted the “mens rea” approach instead. The mens rea approach only allows a defendant to bring evidence of a mental disease or defect to prove that he or she lacked the requisite mental state to be guilty of the crime. It specifically prevents a defendant from presenting evidence that he or she lacked the ability to understand right from wrong. Kahler maintained that the mens rea approach violates the Eighth Amendment and violates the Due Process Clause because it “offends a principle of justice so rooted in the traditions and conscience of our people as to be ranked as fundamental.”

The Kansas Supreme Court disagreed with Kahler, denying all ten allegations and affirming Kahler’s capital murder conviction and death sentence under K.S.A. 21-3439(a)(6). The United States Supreme Court granted Kahler certiorari on March 18, 2019.



Kahler argues that Kansas’ mens rea approach to the insanity defense violates the Due Process Clause of the 14th Amendment because it focuses on a defendant’s intent instead of moral culpability. Kahler contends that the Due Process Clause requires the availability of a legal mechanism excusing defendants for their crimes when they lack moral culpability due to mental illness. Kahler asserts that this legal mechanism is an affirmative defense, specifically the right-and-wrong test for insanity. Kahler explains that this right-and-wrong test finds defendants not morally culpable for their crimes when they cannot appreciate between right and wrong. Kahler explains that the insanity defense is a “fundamental” right—and thus must be given to criminal defendants—because it has been practiced throughout history and is used by a majority of states. Kahler notes that ancient civilizations, English common law, and United States law at the Founding all recognized an affirmative insanity defense. Kahler also argues that the availability of an affirmative insanity defense in forty-five states, the federal government, the U.S. military, and the District of Columbia further supports that this defense is “a fundamental legal principle.”

Kansas counters that the mens rea approach to insanity does not violate the 14th Amendment’s Due Process Clause because it is not a fundamental principle. For instance, Kansas explains that using the right-and-wrong test to determine insanity has not been fixed throughout history and did not develop until the 19th century. Kansas also notes that its mens rea approach originally developed in England and was more established than the right-and-wrong test at the United States’ Founding. Kansas contends that the right-and-wrong test was highly debated and thus not a fundamental legal principle. Kansas emphasizes that states have used many different tests for insanity over time, demonstrating that the right-and-wrong test is not a fundamental right. Kansas also notes that this test is not fundamental because some states have excluded categories of mentally ill defendants, such as those with certain mental diseases, personality disorders, or mild to moderate mental illnesses. Finally, Kansas asserts that the Supreme Court’s Due Process Clause cases grant states the flexibility to determine their own criminal law and they may therefore develop their own insanity test.


Kahler contends that Kansas’ mens rea approach to the insanity defense violates the Eighth Amendment’s protection from cruel and unusual punishment. Kahler explains that the Eighth Amendment forbids practices that were illegal under the common law at the time of the Founding. He therefore argues that at the time of the Founding, the common law prohibited punishing mentally ill defendants and invoked the right-and-wrong test to determine insanity. Kahler asserts that Kansas’ disregarding of the right-and-wrong test means that it will likely convict and punish mentally ill defendants, violating the Eighth Amendment. Kahler also contends that the Eighth Amendment employs the proportionality test which requires a punishment to be proportional to the crime. Kahler argues that mentally ill defendants are not morally culpable for their crimes and are less deserving of punishment. Furthermore, he explains that due to the lack of moral culpability, any punishment of mentally ill defendants would be severe. Therefore, he asserts that Kansas’ lack of an affirmative insanity defense using the right-and-wrong test would likely lead to the punishment of mentally ill individuals and would thus violate the Eighth Amendment’s proportionality rule.

Kansas counters that the mens rea approach to the insanity defense does not violate the Eighth Amendment’s protection from cruel and unusual punishment because founding-era common law did not deem that approach to be cruel and unusual. Kansas contends that the mens rea approach was more deeply rooted in the United States at the Founding than the right-and-wrong test. . Kansas asserts that many of the English legal scholars that were most familiar to early Americans all recognized a close connection between insanity and a lack of mens rea. Kansas further contends that many cases during the Founding did not mention the right-and-wrong test at all, and those that did often tied the test to mens rea. . Kansas also argues that the Eighth Amendment is only intended to forbid cruel and unusual punishments and not to delimit what affirmative defenses must be made available. Kansas notes that Kahler’s interpretation of the Eighth Amendment would greatly expand its scope to address matters typically left to the states, such as criminal law and affirmative defenses.


Kahler argues that the mens rea approach to the insanity defense violates the Eighth Amendment because it does not serve any of the justifications for criminal punishment: retribution, deterrence, incapacitation, and rehabilitation. Kahler contends that these four justifications are not served when the state punishes mentally ill individuals who cannot rationally distinguish between right and wrong. For example, Kahler first argues that retribution is not served because mentally ill individuals who do not understand the difference between right and wrong do not deserve to be punished because they cannot appreciate their moral culpability. Second, Kahler contends that deterrence is not served because punishing mentally ill individuals does not prevent them from committing future crimes since they did not understand the crime’s wrongness. Third, Kahler claims that incapacitation is not served because the punishment does not relate to the duration of the person’s mental illness or how dangerous they are, and therefore the punishment could be too light or harsh depending on the severity of the person’s illness. Fourth, Kahler explains that rehabilitation is not served because “prisons are not equipped to rehabilitate” mentally ill individuals.

Kansas counters that the mens rea approach serves the justifications for criminal punishment. First, Kansas asserts that the mens rea approach serves retribution because it is reasonable for the state to decide “that individuals who voluntarily and intentionally kill another human being are not entirely blameless,” whether or not they understand that their actions are wrong. Kansas also notes that Kahler specifically is worthy of punishment because he committed an intentional and premediated homicide of four people, and thus is not “morally blameless” even if he did not fully understand the wrongfulness of his actions. Second, Kansas contends that the deterrence function is served because fear of punishment could deter individuals from killing, even if they think their crime is not morally wrong. Third, Kansas argues that incapacitation is served because when mentally ill individuals are released from prison, they can be civilly committed to a mental institution if they are still deemed a danger to society. Fourth, Kansas explains that rehabilitation is served because individuals are able to attain mental health treatment while in prison if they are considered mentally ill.


Kahler argues that the use of the mens rea test for insanity was not harmless error. Kahler contends that his case was negatively affected by Kansas’s law precluding the jury from considering mental-illness evidence related to moral culpability. He adds that if not for the state law, he could have presented additional evidence showing that he was mentally ill and did not understand the moral culpability of his actions during the crime. Kahler also explains that Kansas has not met its burden of proving beyond a reasonable doubt that using the mens rea test for insanity was not harmless. Kahler further notes that allowing the jury to consider moral culpability when deciding whether to impose capital punishment is not sufficient to meet Kansas’ burden to show that the error was harmless. Kahler asserts that the jury received many different pieces of evidence related to mental illness and culpability, but no instructions on the weight to give each piece of evidence.

Kansas counters that disallowing the use of the right-and-wrong test of insanity was harmless because “Kahler is not insane.” Kansas explains that Kahler must present evidence showing that he did not understand right from wrong during the crime to use that as a defense. Thus, Kansas argues that using the mens rea test for insanity was harmless because Kahler did not proffer any evidence showing that he did not understand the wrongfulness of his actions. Kansas further contends that this was harmless error because different jury instructions would not have resulted in a different outcome. Specifically, Kansas argues that Kahler could have presented any mitigating evidence during the penalty phase, and that the jury’s decision to sentence Kahler to death demonstrates that the jury would have reached the same outcome in the guilt phase even if the right-and-wrong test for insanity had been used.



The American Civil Liberties Union et al. (“ACLU”), in support of Kahler, attempts to dispel concerns regarding the insanity defense—such as overuse, fictitious claims, and early release. Regarding overuse, the ACLU maintains that although people believe the defense is used in “20% to 50% of all criminal cases,” it is only invoked in about 1% of criminal cases. Additionally, the ACLU contends that the insanity defense is not easy to fake, and in actuality, psychiatrists from both sides agree on the defendant’s mental state in roughly 90% of insanity cases. The American Bar Association (“ABA”) agrees, explaining that most successful insanity defenses are the result of plea bargaining, showing that neither side disputes the defendant’s insanity. It points out that a contested jury trial occurs in less than 15% of adjudications involving the insanity defense. The ACLU also contends that defendants are disincentivized from faking the insanity defense because those who unsuccessfully assert it are detained 22% longer than others who did not use the defense. Finally, the ACLU counters the assertion that the insanity defense allows mentally insane individuals to evade punishment and to reenter society. It explains that such individuals can be civilly committed—involuntarily hospitalized—until they are no longer dangerous. It maintains that such individuals are often held longer than those detained in the prison system.

Lynn Denton, the sister of the deceased Karen Kahler, in support of Kansas, counters that the insanity defense is harmful to society, especially victims of crimes. She explains that she and other victims have an interest in holding perpetrators accountable for their crimes and contends that this interest is affected when a defendant is found not guilty by reason of insanity. For instance, she explains that when defendants successfully invoke the insanity defense, their case moves out of the criminal justice system, thereby reducing transparency and victim participation. She maintains that the criminal justice system is more likely to ensure victim participation through the use of victim-impact statements made to sentencing judges and parole boards. She points out that under the civil commitment regime, victims who want to ensure that their perpetrators are not released, must speak every year at competency sentences, leading to their re-victimization. Additionally, Denton notes that often times, the victims are told that the prosecution will be accepting a plea bargain involving the insanity defense, further excluding the victim from the judicial process.


In support of Kahler, 290 criminal law and mental health law professors (the “Professors”) argue that a moral culpability requirement does not infringe upon the States’ sovereign status. The Professors maintain that incorporating a defendant’s ability to understand the wrongfulness of their actions into the insanity defense still leaves the States considerable freedom to tailor the rest of the defense to meet their citizens’ needs. Kahler points out that States can still decide whether to include a volitional or cognitive component, define “wrongfulness,” and determine who carries the burden of proof and what that burden entails.

In support of Kansas, Utah argues that requiring States to incorporate “moral capacity” into their insanity defenses infringes on the States’ sovereign status. Utah contends that the people, through their legislatures, ought to be able to choose what is worthy of criminal punishment. Utah says this process has always been left to the States. Utah asserts that a constitutional approach to the insanity defense restricts the States’ ability to respond to their citizens’ moral beliefs towards criminal punishment and infringes on the States’ sovereign status.


In support of Kahler, Legal Historians and Sociologists (“Historians”) argue that scholars and philosophers have historically recognized the injustice of punishing people who do not understand right from wrong. The Historians contend that society has recognized an insanity defense for centuries, even for those who intended to commit the crime. According to the Historians, the right-and-wrong test simply restated the historical practice of punishing criminal defendants only when they understood the wrongfulness of their actions. Although the Historians note that states are still experimenting with the insanity defense and have modified the traditional test, they also emphasize that forty-eight jurisdictions still ask whether the defendant understood right from wrong.

In Support of Kansas, Lynn Denton et al. (“Denton”), counters that society’s understanding of mental illness is constantly changing and evolving. Denton argues that adopting a rigid constitutional approach would prevent States from adjusting to future medical and scientific developments and freeze productive dialogue between law and psychiatry. Denton also notes that the Supreme Court over 50 years ago refused to impose a constitutional standard for insanity because society did not understand the best way to accurately test moral capacity. Denton says this rationale continues to counsel against adopting a rigid constitutional approach to the insanity defense.

Edited by 


The authors would like to thank Professor Stephen P. Garvey for his guidance and insights into this case.

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