The U.S. Supreme Court ruled last month that the U.S. Constitution’s Due Process Clause does not require states to provide criminal defendants with an insanity defense to criminal liability. (Kahler v. Kansas (Mar. 23, 2020) __U.S.__ [140 S.Ct. 1021; 206 L.Ed.2nd 312].) Under Kansas law (pursuant to a statutory amendment effective in 1995), defendants are precluded from arguing they were insane and unable to make moral judgments as an excuse for having committed a criminal act. Instead, Kansas law allows defendants to argue that due to a mental defect, they did not intend to commit the crime as an affirmative defense. One’s mental issues may also be argued by a defendant at the time of sentencing as a factor in mitigation. But under Kansas law, insanity itself does not provide a criminal defendant with a complete defense to his or her criminal culpability. In this ruling, the Supreme Court rejected the argument that the Fifth Amendment’s Due Process protections require the acquittal of any defendant who is unable to tell the difference between right and wrong because of a mental defect of some sort. Kansas’ legal theory, eliminating the commonly used defense of insanity, is constitutional, per the U.S. Supreme Court. California, of course, allows for an insanity defense, employing the so-called common law “McNaghten Rule” where a criminal defendant is entitled to an acquittal (i.e., “not guilty by reason of insanity”) if he can prove that he was insane at the time of his or her crime. Per P.C. § 25(b): “In any criminal proceeding, including any juvenile court proceeding, in which a plea of not guilty by reason of insanity is entered, this defense shall be found by the trier of fact only when the accused person proves by a preponderance of the evidence that he or she was incapable of knowing or understanding the nature and quality of his or her act and of distinguishing right from wrong at the time of the commission of the offense.” (See also CALCRIM 3450.) Given California’s current trend towards being soft on criminals, the state is not likely to take this form of exoneration away from criminal defendants anytime in the near future. But should the day ever come when California decides to delete the McNaghten Rule from its statutes, the U.S. Supreme Court says that we have that option