Your browser is unsupported

We recommend using the latest version of IE11, Edge, Chrome, Firefox or Safari.

Kahler V. Kansas: The Supreme Court Case That Decided Upon The Constitutionality Of Replacing The Traditional Insanity Defense With The Mens Rea Approach

On October 7, 2019, the United States Supreme Court heard oral arguments on the case Kahler v. Kansas and discussed the constitutionality of abolishing the traditional insanity defense.[1] On March 23, 2020, the United States Supreme Court held that the Fourteenth Amendment does not require Kansas to adopt an insanity test based on a defendant’s ability to understand that the crime was morally wrong.[2] In other words, the Court ruled that the Due Process Clause does not require the states to adopt the moral incapacity prong of the M’Naghten Test.[3]

The traditional affirmative insanity defense became known as the M’Naghten Test of insanity in the nineteenth century.[4] The M’Naghten Test relieves those criminal defendants from liability if they can prove that they (1) did not know the nature and quality of the act or (2) did not know the action was morally wrong.[5] In general, the traditional insanity defense allows those accused of a crime to be relieved from criminal responsibility as a result of mental disease or defect.[6]

In the twentieth century, several jurisdictions have transitioned toward the mens rea approach to insanity. State legislatures in five states eliminated the affirmative insanity defense and replaced it with the mens rea approach.[7] The mens rea approach allows criminal defendants to introduce evidence showing the existence of mental disease in order to negate intent.[8] In other words, evidence of mental illness can only be used to rebut the mens rea element of the crime, making mental illness essentially irrelevant as a defense.[9] Before the Supreme Court’s ruling in Kahler v. Kansas, there was a circuit split regarding the constitutionality of abolishing the traditional insanity defense.[10] Specifically, there was a divide among the states that had adopted the mens rea approach to insanity[11] and the state of Nevada that had rejected it.[12]

In Kahler v. Kansas, James Kahler became severely distraught after his wife filed for a divorce.[13] He ultimately shot and killed four members of his family and was charged with capital murder.[14] Kansas law only permits the use of psychiatric testimony to show that mental illness prevented a criminal defendant from forming the intent to kill.[15] At trial, an expert for the defense stated that Kahler suffered from severe major depression and could not control his behavior at the time he committed the murders.[16] However, the prosecution’s expert testified that Kahler had the capacity to form the requisite intent, despite being mentally unwell.[17] The State of Kansas also allows defendants to offer additional evidence of mental illness at the sentencing phase.[18] The jury still convicted Kahler of capital murder and imposed the death penalty.[19]

Kahler appealed and the Kansas Supreme Court affirmed his conviction and sentence.[20] Kahler then asked the United States Supreme Court to consider whether the Fourteenth Amendment requires the States to adopt an insanity defense that acquits criminal defendants who could not understand right from wrong when committing the act.[21] The Court held that the Due Process Clause does not require the States to adopt a moral incapacity test for insanity.[22]

In her opinion, Justice Elena Kagan began by saying that Kahler had to overcome a high bar in arguing that the Kansas statute violates his constitutional rights.[23] Kagan explained that a state law regarding criminal liability will only violate due process if the law “offends some principle of justice so rooted in the traditions and conscience of our people as to be ranked as fundamental.”[24] In applying that standard, the Court looks to historical practice, including early judicial decisions.[25]

The Supreme Court has largely left decisions regarding criminal liability to the States.[26] In Powell v. Texas, Justice Marshall explained that the doctrines of mens rea and insanity have “provided the tools for a constantly shifting adjustment of the tension between the evolving aims of the criminal law and changing…medical views of the nature of man.”[27] He further expressed that it would be wrong for the Court to define some sort of insanity test because it would decrease experimentation and “freeze the developing productive dialogue between law and psychiatry into a rigid constitutional mold.”[28]

Based on this reasoning, the Court declined to require the States to adopt a specific insanity test based on a defendant’s ability to recognize right from wrong.[29] Although Kansas does not follow the traditional approach to insanity, it still considers mental health at both trial and sentencing.[30]

Justice Stephen Breyer dissented, and was joined by Justices Ruth Bader Ginsburg and Sonia Sotomayor.[31]Breyer explained how more defendants will be convicted under the mens rea approach to insanity.[32] Breyer also rejected Kansas’ argument that it had not abolished the insanity defense, but simply changed when a defendant can present mental-capacity evidence during the sentencing phase.[33] According to Breyer, history and tradition indicate that insane defendants should not be found guilty in the first place.[34] Under Kansas law, insane defendants are exposed to harsh punishments, including the death penalty.[35] Forty-five states, along with the Federal Government and the District of Colombia, recognize an insanity defense that considers whether the defendant knew the difference between right and wrong.[36] In general, Breyer believes that Kansas’ view of insanity contradicts a fundamental tradition of criminal law.[37]

Because of the Court’s holding in Kahler v. Kansas, several states will likely follow Kansas in adopting the mens rea approach. As a result, courts may see detrimental effects. For instance, a study of mental-disorder claims in Montana found three major effects.[38] First, even though Montana essentially eliminated insanity acquittals, there were still approximately the same amount of mental illness defenses raised by defendants after the mens rea reform.[39] Second, a larger portion of defendants were found guilty and convicted.[40] The increase in convictions confirms that the mens reaapproach exposes severely mentally ill offenders to imprisonment and unjust punishment.[41] Lastly, the study found that a decline in not guilty by reason of insanity acquittals lead to a significant increase in offenders found incompetent to stand trial.[42] In other words, offenders who otherwise would be competent to stand trial but acquitted under the affirmative insanity defense, are now being found incompetent with the replacement of the traditional approach. The charges of those found incompetent to stand trial were often dismissed or deferred, and being incompetent to stand trial did not ensure hospitalization or treatment.[43] Overall, this study demonstrated that the more restrictive mens reaapproach to insanity correlates with less involuntary hospitalization for those defendants that raise the mental disease defense at trial.[44] Only time and experimentation will reveal the full effects of the Kahler v. Kansas decision.



[1] Transcript of Oral Argument, Kahler v. Kansas, No. 18-6135 (U.S. Oct. 7, 2019), 2019 WL 5087137. See also Amy Howe, Argument analysis: Justices open new term with questions and concerns about insanity defense, SCOTUSblog (Oct. 7, 2019, 3:58 PM),

[2] Kahler v. Kansas, 140 S. Ct. 1021, 1027 (2020).

[3] Id.

[4] See M’Naghten’s Case (1843) 8 Eng. Rep. 718 (HL) (establishing the M’Naghten test of legal insanity).

[5] Id. at 722.

[6] Abraham S. Goldstein, The Insanity Defense 9 (1967).

[7] Idaho Code § 18-207 (West 2019); Kan. Stat. Ann. § 22-3219 (West 2019); Mont. Code Ann. 46-14-102 (West 2019); Utah Code Ann. § 76-2-305(1) (West 2020); See also Finger v. State, 27 P.3d 66, 68 (Nev. 2001) (rejecting the mens rea approach).

[8] See State v. Jorrick, 4 P.3d 610, 617 (Kan. 2000) (stating “[t]his approach permits a defendant to introduce expert psychiatric witnesses or evidence to litigate the intent elements of a crime. If the evidence negates the requisite intent, the defendant is entitled to an acquittal”).

[9] Joshua Dressler, Understanding Criminal Law 340 (8th ed. 2018).

[10] See State v. Bethel, 66 P.3d 840, 846 (Kan. 2003) (adopting the mens rea approach to insanity); State v. Korell, 690 P.2d 992 (Mont. 1984); State v. Searcy, 798 P.2d 914 (Idaho 1990); State v. Herrera, 895 P.2d 359 (Utah 1995); see also Finger, 27 P.3d at 86 (rejecting the mens rea approach to insanity).

[11] Bethel, 66 P.3d at 846; Korell, 690 P.2d 992 (Mont. 1984); Searcy, 798 P.2d 914 (Idaho 1990); Herrera, 895 P.2d 359 (Utah 1995).

[12] Finger, 27 P.3d at 86.

[13] Kahler, 140 S. Ct. at 1026–27.

[14] Kahler, 140 S. Ct. at 1027.

[15] Id.; See also Kan. Stat. Ann. § 21-5209 (West 2020).

[16] State v. Kahler, 410 P.3d at 105, 114 (Kan. 2018).

[17] Id.

[18] Kahler, 140 S. Ct. at 1027; See also Kan. Stat. Ann. § 21-6625(a)(6) (West 2020).

[19] Kahler, 140 S. Ct. at 1027.

[20] State v. Kahler, 410 P.3d at 133.

[21] Kahler, 140 S. Ct. at 1027; See Petition for Writ of Certiorari at i, Kahler v. Kansas, No. 18-6135 (U.S. Sept. 28, 2018), 2018 WL 7635903.

[22] Kahler, 140 S. Ct. at 1027.

[23] Id.

[24] Kahler, 140 S. Ct. at 1027 (citing Leland v. Oregon, 343 U.S. 790, 798 (1952)).

[25] Kahler, 140 S. Ct. at 1027 (asking whether a rule is “so entrenched in the central values of our legal system—as to prevent a State from ever choosing another”).

[26] Clark v. Arizona, 548 U.S. 735, 752 n.20 (2006) (stating, “[w]e have never held that the Constitution mandates an insanity defense, nor have we held that the Constitution does not so require. This case does not call upon us to decide the matter”)

[27] Powell v. Texas, 392 U.S. 514, 535-36 (1968).

[28] Id. at 536-37.

[29] Kahler, 140 S. Ct. at 1037.

[30] Id.

[31] Kahler, 140 S. Ct. at 1037-38 (2020) (Breyer, J., dissenting).

[32] Id. at 1038 (Breyer, J., dissenting) (stating, “[c]onsider two similar prosecutions for murder. In Prosecution One, the accused person has shot and killed another person. The evidence at trial proves that, as a result of severe mental illness, he thought the victim was a dog. Prosecution Two is similar but for one thing: The evidence at trial proves that, as a result of severe mental illness, the defendant thought that a dog ordered him to kill the victim. Under the insanity defense as traditionally understood, the government cannot convict either defendant. Under Kansas’ rule, it can convict the second but not the first”).

[33] Id. at 1049 (Breyer, J., dissenting).

[34] Id. (Breyer, J., dissenting).

[35] Id. at 1049-50 (Breyer, J., dissenting).

[36] Id. at 1046 (Breyer, J., dissenting).

[37] Id. at 1050 (Breyer, J., dissenting).

[38] Brief of Amicus Curiae 290 Crim. Law and Mental Health Law Professors in Support of Petitioner’s Request for Reversal and Remand at 14, Kahler v. Kansas, 140 S. Ct. (2019) (No. 18-6135); Lisa Callahan et al., The Hidden Effects of Montana’s “Abolition” of the Insanity Defense, 66 Psychiatric Q. 103 (1995).

[39] Callahan, supra note 38 at 107, 116 (explaining that the number of acquittals due to mental disease dropped from 38 NGRI verdicts in the three years before the change to 6 NGRI acquittals in the six years after the adoption of the mens rea approach).

[40] Id. at 116.

[41] Brief of Amicus Curiae 290 Crim. Law and Mental Health Law Professors, supra note 38 at 14.

[42] Callahan, supra note 38 at 109, 116.

[43] Id. at 116 (explaining how all 38 defendants found NGRI were hospitalized in the three years before the mens rea approach, but less than two-thirds of the 63 of the offenders found incompetent to stand trial received hospitalization in the six years after the change).

[44] Id.