A high point in the modern debate over the enforcement of morality was reached in the UK in the late 1950s and early 1960s. Consisting of a spirited exchange of essays and lectures between Patrick Devlin, a distinguished sitting judge, and H. L. A. Hart, a professor of jurisprudence at Oxford University, the debate was sparked by the publication of a controversial report commissioned by the British government that recommended that the criminal law in the UK be liberalized regarding prostitution and “homosexual offences.” The Hart/Devlin debate centered on sexual morality, but the issues it raised pertain to a much wider range of concerns. This chapter pays particular attention to the distinctions and arguments the debate introduced concerning legal moralism and legal paternalism. Devlin defended a version of legal moralism. Hart rejected legal moralism, but granted the permissibility of legal paternalism. The chapter distinguishes critical legal moralism from the social legal moralism that Devlin proposed. It argues that a plausible form of legal moralism must be informed by critical morality, not social morality. It also defends the plausibility of moral paternalism and legal moralism.