Big Idea 141 is justice
Justice can be considered as the fairness of a situation and is linked to fair treatment another view: 'Justice' (ideally) is the action, or course, that will restore equilibrium to a situation. It's often confused, or conflated, with punishment; but that is really the idea that two wrongs make a right - 'An eye for an eye, a tooth for a tooth.' which is in the realms of 'Divine Justice' ( the moral standard by which God judges human conduct - oh dear).
The article in how stuff works is also illuminating- do we practice justice? Probably not we all have prejudices, but recognising this can be empowering.
The idea of Justice is fundamental to the way that free and fair societies operate, if you think about children crying 'it's not fair' you'll realise how basic an expectation of justice is to most of us.
Why has she got more than me?
So Plato's capturing of 'Just deserts' in The republic epitomises the concept, Justice has two forms:
1) The Justice delivered by the legal system - where people are judged fairly and Justice is handed out in a consistent and even manner.
2) The Justice of a fair society, this has a more political dimension and brings with it ideas of equality and treating people equally.