Starring Matthew McConaughey and Ryan Phillippe. Rated 14A. Opens Friday, March 18, at the Fifth Avenue Cinemas

In The Lincoln Lawyer, Matthew McConaughey plays an L.A. attorney who gets by on quirky charm rather than depth or substance. The same can be said of this crime thriller, which grows sillier, not smarter, as it moves along.

Taken from Michael Connelly’s sun-bleached bestseller, that title is something of an alliterative misnomer. Sure, the star’s slick Mick Haller does some business from the back of his anachronistic town car. (You were expecting references to that rail-splittin’, slave-freein’ president from Illinois?) But he also bumps into unwanted customers at his low-rent apartment, which is slightly less secure than Sam Spade’s third-floor walkup.

The big case here involves a rich kid, played by Ryan Phillippe, who really is too good to be true. Accused of brutalizing a hooker, sonny boy claims to be the victim of a major setup. Pretty soon, though, Mick decides he’s the one who fell into a velvet trap. Indeed, warning flags signal threats—if things don’t go just right in court—to his investigative partner (a longhaired William H. Macy) and his ex-wife, a cuddly prosecutor played by Marisa Tomei.

The latter doesn’t have much to do except drive Mick home when he’s drunk, which is weird because our DUI–prone counsel earlier hired a chauffeur (Laurence Mason) who promptly disappeared from the story only to appear again at the end without explanation. That’s far from the only loose end in the two-hour adaptation, written by John Romano and directed by Brad Furman (The Take), who handles the elements well until he suddenly gets all jiggy with the lens. This car-lovin’ lawyer’s moral conundrum is nifty. But you’d think a guy who sleeps with someone from the DA’s office could get some help hanging a smelly client out to dry.