What this means in detail, though, is complicated and controversial.
Equality and Equity
Generally, though, two things that justice demands are clear.
One is that we should treat people equally. That is, we shouldn't give certain people extra consideration or status for arbitrary reasons. If I get thrown in jail for a certain crime, you should get equal punishment if you commit an identical crime. Same crime, same punishment. Equal pay for equal work. Equal harm, equal compensation. Reciprocity is another way that equality arises: I'll treat you the way you treat me.
Some of humanity's greatest moral efforts have focused on equality. In particular, attempts to push for equal rights under the law, to end discrimination based on race, gender, religion, etc., are based on the ideal of equality. Racism and aristocracy are chiefly objected to on the grounds that they put one race or one family ahead of everyone else arbitrarily and for no good reason.
But, on the other hand, justice also seems to demand equitable treatment. That is, we should treat people differently when there is good reason to do so. People guilty of murder should be treated differently from people who are innocent of it. People who are sick or in need deserve different treatment from those who aren't. The person with the more serious injury goes to the front of the line at the emergency room. The person who works harder should get paid more.
With this in mind, we can identify at least three respects in which we demand equitable treatment for people: need, merit, and culpability.
People who are suffering, who are deprived of freedom or resources, deserve more assistance than those who are not. The Civil Debate Page expands on this in the section on aiding the needy.
People who work harder, who achieve more, or who make greater sacrifices or contributions for the sake of others deserve more consideration, praise, and gratitude that those who do less. The Civil Debate Page expands on this in the section on merit.
People who are innocent of wrongdoing deserve to avoid blame and punishment. People who are guilty of wrongdoing deserve to receive (proportional) blame and punishment for their misdeeds. The Civil Debate Page expands on this in the sections on culpability and defiance.
Of course, these different considerations -- need, merit, and culpability -- often come into conflict with each other (and even themselves), resulting in moral dilemmas:
- A drunken driver crashes into another car, causing himself a potentially fatal injury, and a severe but survivable injury to the other driver: if we can only help one person, should it be the drunken driver, or the innocent victim?
- In return for a pardon, a criminal offers to hand over information sufficient to secure the arrest and conviction of people who have committed more serious crimes: should the government accept the offer?
- Should a scholarship go to the student with higher grades, or the student with less money?
These questions are difficult to answer. But, with a greater understanding of the moral elements and considerations that play a role in such questions, we can have more productive -- more respectful, more dignified -- discussions and debates about matters of justice.