Harvard’s Michael Sandel gives a brilliant introduction to what justice means in his book “Justice: What’s the Right Thing to Do?”
The material is also available on DVD as a series of lively lectures and discussions. See http://www.justiceharvard.org/ as well.
Contrary to what you might expect, it entails the evaluation of various philosophical concepts, across cultures and country borders. Why is something right? Why is something else wrong? What changes if the circumstances are slightly different?