Everything you need to understand or teach The Brethren by John Grisham.
By focusing on flawed characters, Grisham appears intent on commenting on the universal nature of corruption. In his novel, corruption certainly is present in all arms of the United States government. However, he also shows the unofficial prison court, run by unscrupulous men, ironically fulfilling a beneficial role in the prison. Without the ad-hoc court to decide disagreements, there would doubtless be more conflict and even violence in the minimum-security prison. Therefore, Grisham shows some faith in the idea of justice and a court system even while repeatedly reinforcing the theme that all humans are flawed and subject to moral and ethical failings.
Accompanying the theme of corruption is that of greed, for it is greed which drives the brethren in their illicit behavior. It is even greed, greed for power, which leads the congressman Lake to fall. Only the CIA director's corruption is not related to greed...