In recent years, and especially in reaction to actual and perceived security threats, there has been a growing interest in so-called preventive detention or preventive punishment, and an equally growing reaction against it. And although much of the reaction is well-founded, it may at the same time be mis-targeted. Prevention, broadly speaking, pervades the law in general, and the criminal law in particular. And so does the imposition on restrictions based on probabilities and predictions. Once we understand that the law enforcement techniques often criticized for their preventive, probabilistic, and predictive character share many goals and methods with the routine operation of the criminal law, we are better situated to identify more precisely the true source of the concerns.