Kahler v. Kansas

Due process does not require that a test of insanity as a defense to a crime turn on a defendant’s ability to recognize the moral turpitude of his crime.

Petitioner was charged with capital murder. He argued Kansas’ insanity defense violated due process because it allowed conviction of a defendant who was prevented from distinguishing right from wrong due to mental illness. The district court returned a guilty verdict. The Kansas Supreme Court rejected Petitioner’s argument on appeal, holding that its test allowing insanity as a defense to show that he lacked intent to kill was sufficient. The U.S. Supreme Court granted certiorari to decide whether the Due Process Clause requires States to adopt the moral-incapacity test arising from M’Naghten’s Case, 10 Cl. & Fin. 200, 8 Eng. Rep. 718, and held that it does not. The Court reasoned that a state rule about criminal liability only violates Due Process if it “offends some principle of justice so rooted in the traditions and conscience of our people as to be ranked as fundamental.” Leland v. Oregon, 343 U.S. 790, 798 (1952). The Court discussed the gaps in knowledge about the human mind and that they have on more than one occasion refused to adopt a rigid test surrounding such an evolving scientific area of study. Petitioner could have produced evidence showing that his mental incapacity prevented him from developing the requisite intent to kill under Kansas' insanity test but he failed to do so. AFFIRMED.