You may be interested in a This American Life episode called The Psychopath Test. It discusses the PCL-R (Psychopathy Check List—Revised) and how it's used in criminal justice systems. For many years, the creator of the test - which was incredibly accurate in predicting likelihood of reoffending - refused to share it with law enforcement. When it was finally published officially, and started being given to prisoners, it was considered objective science and became used as a reason to not give people parole: It tells the story of one specific prisoner who scored high on the test. It's a very interesting episode.The political reality, Carbone says, is this. In California, not only the board, but the governor must sign off on every parole granted. And there's just no benefit to being seen as soft on crime. So if a psychologist gives a bad report because of a high score on the psychopath test, even if the board or the governor wanted to set that person free, there is, as Carbone points out, no political cover if the prisoner re-offends.