It's a little concept that has to do with being one's brother's keeper.
A good source is the Sermon on the Mount.
A very instructive work on the nature of Justice as you seem to define it is The Merchant of Venice by William Shakespeare. Portia makes a speech about Mercy as a component of Justice that you might want to study for a while. Take your pound of flesh, but don't spill a drop of blood to get it.
