Kevin Deyoung has a helpful article on a definition of social justice.  The term “social justice” is used a lot today and various meaning are attached.  His main point is that we should be careful how we use it.  Notice the key differences below:

In A Conflict of Visions, Thomas Sowell explains the difference between the constrained and unconstrained view of justice. In the unconstrained view justice is a result so that wherever people don’t get “their fair share” or don’t have as much as others there is injustice. If Goldingay is correct, most people assume this unconstrained view when they speak of social justice. For example, the RCA (my denomination) in one of its official study materials includes a glossary which defines justice as “The fair, moral, and impartial treatment of all persons, especially in law. Includes concepts of right relationships and equitable distribution of resources.” By this definition the inequality of opportunities, income, or outcomes is considered an injustice, a situation that in and of itself is sinful, implicates all (or most) of us in society, and demands immediate redress. In the unconstrained vision, the society has a lump of resources and if they are not shared roughly equally, then we do not have social justice.

In the constrained vision, by contrast, justice is a process where people are treated fairly (the first half of the RCA definition). The goal here is not forced redistribution; no one distributed the resources in the first place and no one is wise enough to allocate them for the good of everyone. Justice, in this vision, is upheld through the rule of law, a fair court system, and equitable treatment of all persons regardless of natural diversity. This doesn’t mean that in the constrained vision we shouldn’t care for the poor or that we simply shrug our shoulders and say “oh well” when we see people struggling through life with far fewer opportunities and resources than the rest of us. The Christian must be generous and should care about suffering and the disadvantaged. But in the constrained vision, this care is a matter of compassion, charity, and love, not automatically an issue of justice.

Kevin DeYoung: A Modest Proposal.