This article considers whether 2 recent U.S. Supreme Court cases, Egelhoff v. Montana and Kansas v. Hendricks, signal increasing social and constitutional acceptance of pure preventive detention of dangerous people. Egelhoff 's implication is that the states have wide authority to punish criminals more harshly than they deserve. Hendricks 's implication is that virtually any convicted criminal may be found mentally abnormal and confined civilly at the end of a prison term. The article suggests that the traditional distinction between criminal and civil confinement, based on culpability and nonresponsibility respectively, protects the civil liberty of all citizens but that the new decisions, spurred by fears for public safety, erode this distinction with unconvincing, inconsistent legal and conceptual reasoning concerning culpability and nonresponsibility. A possible increase in social safety is not worth the potential costs of these cases to civil liberty.