Don't Take Advantage
Justice is always best measured from the perspective of the weakest.
Remove not the old landmark; and enter not into the fields of the fatherless: For their redeemer is mighty; he shall plead their cause with thee.
This is a powerful image of social justice. The landmark represents the notion of an entitlement - something fixed and something that assures each party that they will maintain their fair share. However the writer knows that for those who are weak - the fatherless - there is always the grave danger that their rights and entitlements will be eroded.
The idea that God is standing alongside the fatherless is an ancient validation of the perspective articulated by the philosopher John Rawls: a society is best judged on the basis of how it treats those who are least able to protect themselves from exploitation.