A case of insanity: diagnostic relevance in the shadow of Columbine.

As director of a forensic psychiatry fellowship program, I am sometimes asked how important psychiatric diagnoses are in sanity and competency opinions. Given that the legal, usually statutory, definition of mental disease or defect is the primary concern in criminal forensic opinions and that legal definitions do not reflect descriptive diagnoses, what difference does it make whether someone is given a descriptive diagnosis of schizoaffective disorder or schizophrenia? Since the psychotic symptoms and the impact of those symptoms on perception, thought, judgment, mood, behavior, and decisionmaking are most relevant in the criminal forensic setting, is descriptive accuracy that important? After all, in many jurisdictions, how symptoms of mental illness affect capacities is the relevant question asked of forensic psychiatrists and psychologists in the courtroom.