The Morality of Prophylactic Legislation (with Special Reference to Speed Limits, Assisted Suicide, Torture, and Detention Without Trial)

My subject is the morality of prophylactic legislation. What do I mean by ‘prophylactic’ legislation? Let me illustrate the concept by drawing a contrast with the most famous hypothetical case in the scholarly literature of Anglo-American jurisprudence. During the course of their debate over the relation between law and morality, Lon Fuller and H. L. A. Hart disagreed about what tools are needed to discern the meaning and scope of a rule barring vehicles from a public park. Hart and Fuller clashed over whether legislative purpose and considerations of morality enter into the process of discerning what Hart famously called the ‘core of settled meaning’. They themselves did not disagree about the fact that there will be cases at the margin of this and every rule, but the example has since come to illustrate the various positions one can take on marginal applications, especially the following question: when, if ever, should ambiguous statutory language be construed to reach circumstances that were not specifically contemplated by the legislature?