The Ten Commandments, especially the latter six, which are universal irrespective of an individual's views on the existence of a higher being, represent social justice in that they were intended to establish a level playing field for all of humanity. The concept or idea of "social justice" is to provide for all equal opportunity and the equal distribution of resources or wealth. These universal principles of right and wrong should, in theory, guide human conduct. Because the Ten Commandments were issued by a higher being for the conduct of human behavior, that higher being, God, acts, especially in the Old Testament, as governor, with certain individuals, Moses, chosen as his administrators of social justice.
While God, in the old Testament, establishes a hierarchy of sorts, with Aaron and the Levites enjoying a somewhat exalted position, the equal treatment of all and the requirement that God and only God be above humanity are the guiding principles. To allow any individual or group of individuals to emerge above the rest of humanity in the manner of a pharaoh or dictator is to violate God's will and undermine the concept of social justice.
In short, the Ten Commandments establish the framework within which the pursuit of social justice can be achieved. Because the commandments were the provenance of God, nothing humanity does can usurp that authority. We are all equal under God's law.