The Brethren Themes
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; his fall appears more related to the old maxim that power corrupts.
With the actions of the CIA director, Grisham explores the question of when the ends justify the means. If a government leader believes his country to be in peril, does that justify any action on his part in its defense? If so, what exactly is he defending? What defines a "country"? These are some of the philosophical questions Grisham explores. After building a compelling motivational case to justify drastic action, Grisham does a masterful job of arguing through the text that the ends do not justify the means.