Clark v. Arizona

As I understand the Court’s opinion, it distinguishes among three categories of evidence related to insanity: (1) fact-related evidence as to the defendant’s specific state of mind at the time of the crime, e. g., evidence that shows he *780thought the policeman was not a human being; (2) expert opinion evidence that the defendant suffered from a mental disease that would have affected his capacity to form an intent to kill a policeman, e. g., that he suffers from a disease of a kind where powerful voices command the sufferer to kill; and (3) expert opinion evidence that the defendant was legally…