Impartiality rightly lies at the heart of our criminal justice system today. The same is true of the criminal and civil justice systems in the Old Testament (see Deuteronomy 16:19).
But when it comes to social justice a far different emphasis emerges. With respect to social justice (commonly defined as how wealth and power is distributed in the society) Scripture requires definite partiality or bias towards one section of the population. The justice of God requires that special concern be shown to the poor, the widows, the orphans, and for the immigrants (referred to in scripture as the sojourners). In fact, the litmus test of Scripture on whether justice is being done is the plight of the poor and the needy in society. The true measure of justice is how the most vulnerable members of the community make out (see Exodus 22:21-24).
Most people are worried by a concept of bias and consider that partiality seems contrary to the term justice. But what Scripture recognises is that treating people the same will not achieve justice when a large power imbalance exists.
God’s justice is rightly biased in favour of the poor and oppressed for two main reasons: Firstly, the poor are more frequently the victims of injustice than others; secondly, God is rightly biased towards the poor because the way they are forced to live violates God’s purpose for the world.
God is not therefore so much biased towards the poor as he is biased against poverty and oppression. When grinding poverty, homelessness and hunger exist, that is evil and contrary to God’s will and purpose. God’s world does not have some lacking basic needs while others live in opulence and wealth.
That is why in Scripture meeting the needs of the poor is not seen as an act of charity but a work of justice-making. This work moves the world in the direction of God’s intention for it. Charity can enslave a population (consider welfare dependency, for example). Justice does not enslave, but liberates as it seeks to empower the weak so that they can participate fully in society.
From the 2006 Coutts Memorial Lecture, given by Major Campbell Roberts at The Salvation Army College of Further Education in Sydney, Australia. Part 4 of 5 on the centrality of Biblical Justice.

Major Campbell Roberts is the Director of The New Zealand, Fiji and Tonga Territory Social Policy and Parliamentary Unit. Campbell has spent a lifetime of work as a Salvation Army Officer working on issues of social policy and programmes that will assist people in poverty in New Zealand. His past roles have included national directorship of The Salvation Army Social services, and the command of The Salvation Army in the South Island.