More than in other genres, casting tends to be make-or-break for a romantic comedy. Not just because there has to be chemistry between the two leads but also because the audience is asking: What does he see in her, or she in him? In order to be plausible mates in viewers' eyes, each performer needs the right qualities apart from his or her co-star.

Julianne Moore and Pierce Brosnan play opposing divorce counsel in Laws of Attraction, a battle-of-the-sexes romantic comedy shooting for sophisticated screwball. You won't need a keen legal mind to judge it more talky than fast-talking. And while the script is the main culprit, casting is problematic.

Even if Ian Fleming had never invented James Bond, Brosnan belongs in front of a Martini bar and not the legal bar. The doll-like Moore appears too fragile for a screwball comedy but her effort is appreciated. Brosnan's screen presence allows him to coast on his charm -- as if channeling Cary Grant is enough. His likeable nonchalance draws you in. Moore works harder, yet just as she didn't cut it as an FBI agent in Hannibal, she can't pass as a cutthroat barrister. She projects a different kind of intelligence -- an interior, brooding quality on display in her Oscar-nominated roles in Far from Heaven and The Hours.

Brosnan's sketchily drawn persona is a slightly mysterious, disheveled romantic. Moore's high-powered lawyer is cynical about romance and marriage. She's also deeply insecure, signaled by her clandestine consumption of sugary treats and watching the Weather Channel on a Friday night instead of dating. Beyond that, the script skirts the laws of good plotting and characterization. The story is supposed to hinge on the the couple's incompatibility when it comes to love. It's a pleasant muddle, partly because they jump in the sack much earlier than custom (for good structural reasons) dictates.

Their big case, the divorce of a rock star (Michael Sheen) and a fashion designer (Parker Posey), involves a couple of trips to Ireland to sort out contested marital assets, specifically a castle. During a night of drinking in the Emerald Isle, the attorneys get hitched. They return to New York, hiding their matrimonial status until the gossip pages run the item.

Neither actor lacks sex appeal. Viewers won't have any problem buying the sexual attraction. As is often the case, however, the secondary characters are far more interesting. Frances Fisher intrigues as Moore’s oversexed, socialite mom, the type who has fat from her backside injected into her lips. Posey and Sheen deserve more screen time as the bickering celebrity couple, and, as a judge, Nora Dunn maximizes her moments. 

Stars of the great romantic comedies of the 1930s and '40s had the advantage of working with writers like Ruth Gordon and Garson Kanin, and directors of Howard Hawks and George Cukor's caliber. Laws of Attraction director Peter Howitt's credits include last year's Rowan Atkinson comedy Johnny English. Screenwriters Aline Brosh McKenna and Robert Harling have worthy credits under their belts (Steel Magnolias, First Wives Club) and manage a few witticisms. Yet overall it's faint stuff. Casting Spencer Tracy and Katharine Hepburn wouldn't even help much. 

(Released by New Line Cinema and rated "PG-13" for sexual content and language.)