At the Library of Law and Liberty, Dalrymple writes about the recent murders committed by Satoshi Uematsu in Japan and Adel Kermiche in France. Uematsu, you may remember, stabbed 19 handicapped people to death, and Kermiche was one of the two jihadists who slit the throat of a priest in Normandy. Neither had a history of violence, although Kermiche had been arrested for trying to join the terrorists in Syria. How then could their crimes have been prevented?
These two cases show just how fallible are judgments of immediate or remote dangerousness. It is unlikely that the Japanese psychiatrists and the French examining magistrate were fools or negligent in any straightforward way. Instead both were prey to the ineradicable problem of the false positive and the false negative that, absent perfect discrimination, haunts even the best of scientific tests applied to humans. Inaccuracy will continue forever to bedevil predictions of human behavior (though, of course, perfectly predictable human behavior would lead to even worse horrors).
If this is the case, arbitrariness is now an important quality of criminal justice in the United States, Britain, and elsewhere, countries that pride themselves—falsely—on valuing the rule of law above all. I refer to the use of parole for prisoners, which depends so heavily on speculation on what prisoners might do if released.