McCulloch v. Commonwealth

James McCulloch (defendant) confessed to murdering his wife and asserted an insanity defense at trial. A court-appointed psychologist, the single mental-health evaluation to which McCulloch was statutorily entitled as an indigent defendant, found he was probably sane at the time of the killing. McCulloch sought a second evaluation by the psychiatrist who had once treated him for a head wound, arguing that psychiatrist was better qualified to explain how the old injury affected his later behavior; the trial judge denied this, finding the former psychiatrist unqualified to opine on McCulloch's mental state at the time of the murder and a second evaluation unlikely to change the result. The judge also excluded lay witnesses who would testify McCulloch seemed "crazy" or "depressed," because McCulloch had not first introduced any expert or factual evidence of insanity. The jury convicted McCulloch, and he appealed.