In moral and political thought, claims are frequently made in the name of justice. Claims are made in the name of other concepts; charity, efficiency, community, care, and so on. But what is special about justice? What is the difference between an injustice and other forms of moral wrongdoing? I seek to do three things in this presentation. Firstly, to show that there is considerable disagreement and unclarity on this issue in contemporary political philosophy. Secondly, to present a three-stage methodology for conceptual clarification. Thirdly, to demonstrate the application of this methodology to the concept of justice. I suggest, tentatively, that justice might be understood as a moral standard which assesses the extent to which an institutional order protects rights. I will finish by expressing some of my own scepticism about this conclusion, and suggest avenues for further research.