John Leslie Mackie (1917-1981) was one of the most influential philosophers of the twentieth century. His published works spanned many areas, but he is not well known as a political philosopher. In the late 1970s, however, Mackie turned his attention to issues concerning justice. In a series of writings, Mackie built a case for a unique right-based approach to political philosophy, in part by delivering incisive critiques of theories dominant at the time. His most comprehensive work in this area is Theories of Justice and Rights--a previously unpublished manuscript that finally sees the light of day in this volume. Also included are two of Mackie's previously published papers, written during the same period: 'Can There Be a Right-Based Moral Theory?' (1978) and 'Rights, Utility, and External Costs' (1985). Some of Mackie's arguments in these works draw on the metaethical conclusions in his seminal book Ethics: Inventing Right and Wrong (1977). The editorial introduction canvasses the
