The purpose of this article is to establish that contemporary private law theory has located no foolproof conception of interpersonal justice. I examine four accounts and find them wanting: the instrumentalist deterrence and loss-spreading approaches of economists; Kantian right and corrective justice; critical and social justice accounts; and the human flourishing approach. If my critiques are justified, this leaves us with the enigma of ‘interpersonal justice’. I consider three options going forward, rejecting the suggestion that we should abandon the search for a theoretical concept or be content with a modus vivendi. I sketch a third option, ‘emancipating interpersonal justice’, drawing from the resources of contractualist philosophy, to suggest that interpersonal justice is not a unitary concept or single regulative idea but a framework for determining what we owe each other in different spheres of interaction, and propose how this might illume certain questions of private law theory.