James, in keeping with Isaiah and all of the OT prophets, calls for justice in the marketplace and workplace.  Don’t naively think that the cry for justice went out with the OT prophets.  Listen to this NT message, “Behold, the wages of the laborers who mowed your fields, which you kept back by fraud, are crying out against you, and the cries of the harvesters have reached the ears of the Lord of hosts” (James 5:4 ESV).  As surely as God heard the cry of injustice arising from Israel in Egypt, so His ear still hears the cries of the oppressed from around the world.  Both Isaiah and Jeremiah remind us that if we live in this world and ignore the cries of the oppressed then God will not hear our prayers either.  Mark it down!