The relationship between morality and law is one of the issues that has provoked considerable controversies. Among others, an important discussion is whether obeying “conventional morality” in public and/or private spheres should be legally enforced by legislators. In this paper, we will look at the controversies over the issue of the “legal enforcement of morality” in the well-known debate between Herbert Hart and Patrick Devlin. In light of Richard Hare's moral philosophy, we will begin by distinguishing three realms of morality. We will then clarify Deviln's view on “conventional morality”, employing the terminology derived from Hare's moral philosophy. After elaborating the implications, consequences, and roots of “conventional morality...