Here are more quotes from Nicholas Wolterstorff's Justice: Rights and Wrongs (Princeton: Princeton University Press, 2008).
Citing Oliver O'Donovan's The Desire of the Nations (1996):
[The conception of justice in the Old Testament] is often obscured by the influence of a quite different conception of justice, classical and Aristotelian in inspiration, built on the twin notions of appropriateness and proportionate equality - justice as receiving ones own and being in social equilibrium. Mishpat is primarily a judicial performance. When "judgment" is present , it is not a state of affairs that obtains but an activity that is duly carried out... So, for example, when Amos calls for mishpat to "roll on like a river," he means precisely that the stream of juridical activity should not be allowed to dry up. (page 69 in Justice: Rights and Wrongs)
The following quotes are directly from Wolterstorff.
[J]ust as we use our word "justice" to speak of both primary and rectifying justice, so Israel used its word "mishpat" to speak of both. (p 75)
They were downtrodden as our older English translations nicely put it. The rich and the powerful put them down, tread on them, trampled them. Rendering justice to them is often described as "lifting them up." (p 76)
Rather often what the writers [of the Old Testament] have in view, when speaking of the plight of widows, orphans, aliens, and the impoverished, is the collapse or perversion of the judicial system. A place midway between Brueggemann's emphasis on primary justice in Israel and O'Donovan's on rectifying justice seems to me the right place to be. (p 78)
Injustice is not equally distributed. The low ones enjoy those goods to which they have a right - food, clothing, voice, security, whatever - far less than do the high and mighty ones. (p 79)
Israel's religion was a religion of salvation, not of contemplation - that is what accounts for the mantra of the widows, the orphans, the aliens, and the poor. Not a religion of salvation from this earthly existence but a religion of salvation from injustice in this earthly existence. (p 79)
Yahweh's pursuit of justice and Yahweh's injunction to practice justice are grounded in Yahweh's love. (p 82)
Injustice is perforce the impairment of shalom. That is why God loves justice. God desires the flourishing of each and every one of God's human creatures; justice is indispensable to that. Love and justice are not pitted against each other but intertwined. (p 82)
God holds human beings accountable for doing justice; and God is himself committed to justice, both in the sense that God does justice and in the sense that God works to bring it about that human beings treat each other justly. Underlying these two themes is God's love of justice. (p 89)
Israel's writers were implicitly working with the conception of justice as inherent rights rather than with that of justice as right order. (p 91)
The assumption of Israel's writers that God holds us accountable for doing justice has the consequence that when we fail to do justice, we wrong God. We not only fail in our obligations to God. We wrong God, deprive God of that to which God has a right. (p 91)
What Israel's writers presuppose, of course, is that God has the right to hold us accountable for doing justice. (p 93)
Surely, God does not have these rights on account of some norm that applies to him! They are not conferred upon God. They belong to God inherently; they come along with what god is and what God does. (p 94)