Sex offenders were once taken to be exemplary of the underlying psychopathological basis of crime. Today their significance is very different. Rather than occasions for testing our modernist faith in scientific rationality, they have become a lesson in the intransigence of evil. Recent laws aimed at addressing sex offenders reflect a transformation in the penal process that has been called the “new penology.” This new penology sees crime as a problem of managing high-risk categories and subpopulations, not normalizing individuals to community norms. Kansas v. Hendricks and recent cases upholding the constitutionality of “Megan's Law” open a window into the operation of the new penology and reveal the degree to which its features are largely immune from constitutional limits established by judicial review.