Or anyone else, for that matter. Tom Widiger, who served as head of research for DSM-IV, says "There are lots of studies which show that clinicians diagnose most of their patients with one particular disorder and really don't systematically assess for other disorders. They have a bias in reference to the disorder that they are especially interested in treating and believe that most of their patients have."

The reason should be obvious -- unlike medicine, psychological diagnoses rely on assessing symptoms, not the detection and treatment of causes.

Psychiatrists and psychologists who serve on parole boards have a record no better than chance. When they say that a person is no longer a threat and merits release, based on their accuracy and predictive track record, they might as well flip a coin.