Basics of these three:
- Mill's Utilitarian view: justice is done by maximizing the average utility for all people in a society. Something is just if if it increases the overall utility (the welfare) of the society.
- Rawls' "fairness" view: justice is done if and only if EVERYONE's rights are protected AND soceity is arranged so as to provide equal opportunities for rich and poor. This differs from Mill's view in that you can't take away one person's rights for the benefit of the whole.
- Nozick's Libertarian view: justice is only done when people are allowed to keep the things that they legitimately own. It is only through people's efforts that property comes into existence. The government has no right to take it from them if they acquire or create it legitimately.
Is that what you're looking for or is there a more specific question you wanted to ask?