Proportionality between actions and consequences.
Proper procedure: independent court, assistance during the trial, etc.
In many concrete situations, one of these principles is more relevant or applicable than the others. But taken together, they cover most situations that require a just decision.
Argue with a couple of examples that justice is sometimes a matter of equality and sometimes a matter of equity.
Research the topic of affirmative action (or positive discrimination as it is also called):
What is affirmative action?
Give an example of positive discrimination, preferably located in Spain.
What is the connection of affirmative action with the topic of justice?
What is social justice? Origins and goals.
Social justice is the idea that government institutions and non-governmental organizations should ensure a just distribution of benefits, costs and opportunities throughout the whole society.
A socially just society is a society that:
Opposes marginalisation and promotes equal opportunity.
Opposes exploitation and promotes a just distribution of benefits.
Opposes extreme inequality and promotes redistributive, progressive taxation.
This idea emerged in the late 19th century and has been debated since them.
Some thinkers have denounced the notion of social justice as a conceptual mistake. According to those thinkers, justice or injustice is a property of individual actions such as a theft, a murder or a fraud. In all these crimes, there is always a identified culprit that must repair the damage and deserves punishment. But social marginalisation or inequality have no concrete culprit. They are the results of a social system. No concrete individual is responsible of them.
In addition to this not very convincing argument, those thinkers add a second one: in its attempts to achieve a more egalitarian society, governments do more harm than good: they reduce the (economic) freedom of its citizens and they create new injustices and imbalances in the society.
However, the majority of political thinkers consider that social justice can be achieved or at least promoted without damaging basic freedoms and, if done well, without creating new injustices.
Before examining the moderate position of John Rawls on the subject, we may examine two extreme conceptions of social justice:
libertarian anarchists
communitarian anarchists
An introduction to libertarian ideas.