[JURIST] The US Supreme Court [official website; JURIST news archive] on Thursday upheld Arizona's law governing insanity defenses in criminal cases, ruling in Clark v. Arizona [Duke Law case backgrounder; JURIST report] that the state's approach does not violate constitutional due process. In June 2000 at the age of 17, Eric Clark, a diagnosed paranoid schizophrenic, shot and killed police officer Jeff Moritz because he allegedly believed that Moritz was an extraterrestrial. At trial, Clark's lawyers were not allowed to introduce evidence of Clark's mental state that was meant to disprove criminal intent, and the trial court's decision was upheld on appeal [opinion, PDF].
Under Arizona law, a defendant can be found guilty but insane if he can prove that "at the time of the commission of the criminal act [he] was afflicted with a mental disease or defect of such severity that [he] did not know the criminal act was wrong," and the Court ruled that this formulation did not "in theory nor in practice ... deprive Clark of due process." The Court also upheld the Arizona Supreme Court's ruling that evidence of a defendant's mental incapacity could not be considered to negate mens rea. Read the Court's majority opinion [text] per Justice Souter, along with a concurrence in part and dissent in part [text] from Justice Breyer, and a dissent [text] from Justice Kennedy, who was joined by Justices Stevens and Ginsburg. AP has more.