OCTOBER TERM, 2019
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.
SUPREME COURT OF THE UNITED STATES
KAHLER v. KANSAS
CERTIORARI TO THE SUPREME COURT OF KANSAS
No. 18–6135. Argued October 7, 2019—Decided March 23, 2020
In Clark v. Arizona, 548 U. S. 735, this Court catalogued the diverse
strains of the insanity defense that States have adopted to absolve
mentally ill defendants of criminal culpability. Two—the cognitive
and moral incapacity tests—appear as alternative pathways to acquit-
tal in the landmark English ruling M’Naghten’s Case, 10 Cl. & Fin.
200, 8 Eng. Rep. 718. The moral incapacity test asks whether a de-
fendant’s illness left him unable to distinguish right from wrong with
respect to his criminal conduct. Respondent Kansas has adopted the
cognitive incapacity test, which examines whether a defendant was
able to understand what he was doing when he committed a crime.
Specifically, under Kansas law a defendant may raise mental illness
to show that he “lacked the culpable mental state required as an ele-
ment of the offense charged,” Kan. Stat. Ann §21–5209. Kansas does
not recognize any additional way that mental illness can produce an
acquittal, although a defendant may use evidence of mental illness to
argue for a lessened punishment at sentencing. See §§21–
6815(c)(1)(C), 21–6625(a). In particular, Kansas does not recognize a
Kansas charged petitioner James Kahler with capital murder after
he shot and killed four family members. Prior to trial, he argued that
Kansas’s insanity defense violates due pr