Amidst all the interest in Hamdan, criminal law types out there won’t want to miss today’s opinions in Clark v. Arizona, on the constitutional requirements of the insanity defense. The vote was 6-3, with Justice Souter writing the majority opinion joined by Breyer, Thomas, Scalia, Roberts and Alito. From the majority opinion:
[I]t is clear that no particular formulation has evolved into a baseline for due process, and that the insanity rule, like the conceptualization of criminal offenses, is substantially open to state choice. Indeed, the legitimacy of such choice is the more obvious when one considers the interplay of legal concepts of mental illness or deficiency required for an insanity defense, with the medical concepts of mental abnormality that influence the expert opinion testimony by psychologists and psychiatrists commonly introduced to support or contest insanity claims. For medical definitions devised to justify treatment, like legal ones devised to excuse from conventional criminal responsibility, are subject to flux and disagreement. There being such fodder for reasonable debate about what the cognate legal and medical tests should be, due process imposes no single canonical formulation of legal insanity.
Justice Kennedy dissented, joined by Stevens and Ginsburg.