[Isaiah] had to contend with many difficulties, for the moral and spiritual condition of the people was corrupt. The rich oppressed the poor, and revelled in wanton luxury; justice was shamelessly bought and sold.First, I'll take note with the phrase "the rich oppressed the poor". Part of my complaint is that it is so generic: every moral and political programme that has ever existed has had a complaint of this kind (even Objectivism!), regardless of whether the poor were even literate enough to record their complaints for themselves. But more than that, it gives a misleading impression of the nature and cause of the oppression. It was definitely the case in hierarchical societies, such as that of Uzziah's monarchy in ancient Israel, that there tended to be significant oppression of the peasantry by the elite. It was also the case that the oppressors were in general much richer than the people they were oppressing. But the text I quoted gives the misleading impression that it was because of their riches that people were able to exercise oppression, rather than the oppression being the source of their wealth.
Secondly, it is complained that "justice was... bought and sold." Going all Brennan/Jaworsky: what, precisely is wrong with that? My suspicion is that the complaint refers to situations such as the following scenario: Aaron wrongs Bathsheba, so Bathsheba takes Aaron to court. However, the judge, Caleb, accepts a bribe from Aaron to pronounce wrongly, so that justice is not done.
But attributing the problem to "the buying and selling of justice" is misdiagnosing the problem. Rather, the issue is one of misallocation of rights. Let us suppose that Aaron's wrongdoing created a right of restitution, R. We would tend to assume that R is owned by Bathsheba. For Bathsheba to have the right to sell R is very useful: exercising the right may well require time or money that she does not have. Instead she might sell the case on to someone more able to pursue it, and take the proceeds of the sale as her restitution. The buying and selling of justice is not only morally acceptable, but serves a valuable purpose.
The problem, in our case, is that the right of restitution did not in practice reside with Bathsheba: it went to Caleb. Note that Aaron still ended up paying for his crime (though perhaps less than he otherwise would have had to): the problem lies less with a failure to punish Aaron than with a failure to make Bathsheba whole.