Apparently, this is meant to be a cautionary tale about the way that power can easily corrupt even the most honest and well-intentioned of men (Stark first campaigns for local office in his hometown by taking on construction-company kickbacks to the local city council), but Zaillian omits so much of Robert Penn Warren's novel that he seems to forget the part that shows Stark going from honorable to corrupt. In one scene, he's rallying the state's oppressed poor against the evil corporate oil interests, and in the next he's being considered for impeachment because of his liberal use of bribery and blackmail.
Whom, exactly, does Stark bribe and blackmail? That's not quite clear, as Zaillian's script lurches from one event to another with seemingly no connective thread, and his time frame is maddeningly fuzzy. Jack experiences tortured flashbacks to his childhood relationship with Anne Stanton (Kate Winslet) and her brother Adam (Mark Ruffalo), neither of whom make significant appearances until almost halfway through the movie, and whose seemingly important roles in the mounting plot are nearly inscrutable until they're past being relevant.
Penn blusters and blubbers and exhibits the only credible Southern accent in the film, but his character is just a collection of good-ol'-boy stereotypes and political-rhetoric clichés (it's no coincidence that James Carville is one of the film's producers). We never understand why Stark is so committed to standing up for the common man, and we understand even less why he allows himself to become so completely and immediately corrupt.
That wouldn't necessarily be a problem, since Jack, not Stark, is the film's real protagonist, but Law is limp and distant as Jack, whose motivations and inner thoughts are just as unclear as Stark's, despite his heavy-handed narration. Zaillian's entire directorial style is heavy-handed, from the narration to the pompous James Horner score to the endless, symbolic shots of crosses in every conceivable location, meant to convey, I don't know, something about redemption, maybe? Even though they show up every 10 minutes or so, their function is indeterminate, not nearly as crushingly obvious as the close-up of a lion-shaped inlay on a chair just after a reference to Stark foe Judge Irwin (Anthony Hopkins) as—you guessed it—a lion.
It's hard to believe that so many good actors (Patricia Clarkson and James Gandolfini round out the cast as two of Stark's aides) can be put to such poor use, but Zaillian manages to miscast nearly every role, and none of the actors can overcome the slapdash plotting to make their characters interesting or believable. Penn comes off best by sheer force of will, but his performance is mostly a lot of yelling and hand-waving. Try as he might, he can't cover up the fact that the movie he's in is an incoherent mess.