What is the difference between a claim of justice and any other kind of moral claim?

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.