Justice is a primary theme in this novel, as is the case in every John Grisham novel that I have ever read. It is the quest for justice that sends Darby Shaw on a mission to find the reason behind the slaying of two seemingly unrelated supreme court justices.

Environmental issues are another theme in this great novel. This is revealed when it turns out that the murders relate to a case involving a business man attempting to access oil in a Louisiana marshland, which is the home to an endangered bird—the Brown Pelican.

A third theme is suspense, and after her boyfriend is killed in a car bombing which was intended to kill both of them, law student Darby Shaw realizes that she is mortal danger.

Working with a reporter, she ultimately discovers both the truth and a new chance at love, meaning that right prevailing over wrong becomes a fourth theme.

The Pelican Brief highlights the critical importance of exposing truth and corruption, even in the face of danger. John Grisham is renowned for his expertise in penning legal thrillers, and he often utilizes young lawyers or law students to lead the fight for justice when dishonestly and fraud run rampant within established institutions. In this novel, Darby Shaw, a law student at Tulane, discovers a link between two murdered Supreme Court justices and a businessman's attempt to drill for oil in the midst of protected Louisiana marshland. After Darby's legal brief highlighting this connection is circulated among government agencies and an attempt is made to take her life, she flees the pursuing assassins and befriends reporter Gray Grantham with the goal of exposing and publicizing the scandal. In addition to this main theme of exposing truth, themes of survival, heroism, overcoming odds, and good triumphing over evil are prevalent.

The author, John Grisham, is first and foremost a lawyer, and the themes found in 'The Pelican Brief' recur in all his works. Grisham is preoccupied with the abuse of public confidence and corruption in general in political circles, but he is also very keen on showing how a few ethical individuals - through perserverence, intelligence and a bit of luck - can break through bureaucratic red tape just the same.

There is an element of poetic justice in Grisham's novels.  Rarely do his "bad guys" get off scot free forever, although a couple of times (I'm thinking primarily of 'The Partner' here) "the big one" does indeed get away.