““Kill’’ is based on John Grisham’s first novel, regarded by his fans as his most brilliant book and by his detractors as the only halfway decent one. (Director Schumacher has already tackled Grisham with ““The Client’’ and vigilantism with ““Falling Down.’’) Here, Hailey’s trial turns into a dated, ’60s-ish spectacle. Blacks riot with the Ku Klux Klan. The National Guard arrives. And people sell T shirts reading both FREE CARL HAILEY and FRY CARL HAILEY. Brigance gets death threats, so his wife (Ashley Judd) whisks their daughter out of town. He stands his ground, staring down racism with a ragtag team that includes a law student eager to get into his legal briefs (Sandra Bullock). ““Kill’’ is a disappointing movie: slow, overpopulated and muddled in its thinking. But McConaughey and Jackson act their butts off.

McConaughey’s butt has already gotten plenty of attention, thanks to a blizzard of publicity. Hype or no, it’s thrilling to watch an unknown become a star. McConaughey is smart and sexy and physical, and he’s got a wonderfully subtle rapport with Jackson, who gives one of the most wrenching performances of his busy career. Bullock has a small part – she speaks her first line 40 minutes into the movie – and doesn’t have the gravitas to pull off tirades against capital punishment. But Warner Bros. wouldn’t have made ““Kill’’ without her name above the title. To her credit, she didn’t trash her trailer and demand more screen time.

The real trouble with ““Kill’’ is that its ethics are dodgy. Brigance says he wants to prove a black man can get a fair trial in the South. But wait a minute: didn’t Hailey murder two guys wearing handcuffs, or did we miss something? He may be morally innocent – and your heart will go out to him, unless you prefer Kiefer Sutherland in a hood – but that doesn’t make him legally innocent. Brigance’s plan is to make the jurors so ashamed of their own racism that they’ll let his client walk. Still, even if you have a soft spot for vigilantes, you’ll wish Hailey had let the rapists have their day in court and then shot them. ““A Time to Kill’’ wants to be a victory march, but it’s a compromised crusade.