In this Sunday’s first reading (Amos 5:6-7; 10-15) the prophet invites his listeners to establish justice in the gate (Amos 5:15) by loving what is good and rejecting all that is evil.
In ancient Israel the gates of towns were the place where justice was administered and those in authority regulated the affairs of the inhabitants (e.g. see Book of Ruth). Therefore, when Amos calls to establish justice in the gate he also denounces the corruption of a system that cares neither for those at the margins of society nor for those in need.
For the prophet the administration of justice and politics have been serving the selfish agendas of those who administered them. The only solution to this situation is a complete, wholehearted return to God.