The legal system seems to go easier on people with wealth and status.
By focusing the novel on two concurrent legal battles, Lippard shows the schism between what a person without resources can do for their defense, and what a person with power and money can do through the work of lawyers. Basically, the novel argues that truly heinous crimes are often left without justice because the defendant can afford to buy a lawyer who is intelligent enough to get him off, and unethical enough to take such a case. Meanwhile, a man is condemned for the ethically confusing honor-killing he performed by murdering the man who brutally raped his sister.
The wealthy and powerful are the most prone to debauchery and evil.
In the mid-19th century, it was becoming well-known (either from fact or from rumor) that the wealthy and powerful were involved in debauchery clubs, and this novel captures some of those ideas, showing that power and wealth seem to lead a person to believe that they are above morality.
The religious underpinning of American society is gone.
New England was originally settled by religious sects that were seeking refuge from religious persecution. These included the Puritans, the Quakers, the Dutch Reformers, and on and on. But the core argument of this novel is that those elements are basically just trivia at this point, because the strict attention to social justice that New England was famous for is nowhere to be seen, and injustices are being committed without consequence. Therefore the society is not religious anymore, especially the upperclass. For instance, the only Quaker in the novel is leaving the city forever, but the book is named for the Quakers.
The title, "City of Brotherly Love," is nothing but a joke in bad taste.
By drawing so much attention to the setting, Lippard reminds the reader that historically, New England has been regarded for its religious history, but the 'brotherly love' of the city allows innocent teenage victims to be raped without consequence, and the disparagement of the lower class. So basically, the name Philadelphia is a misnomer, since there is no love between the wealthy and the poor.
