I suppose a show about lawyers must last an hour because that's how they charge. But Fox really should pay us to watch "Head Cases."

Debuting at 9 tonight, the series is an odd-couple comedy with hints of "Rain Man." The plot pairs successful white-shoe attorney Jason Payne (Chris O'Donnell) with a lawyer named Shultz (Adam Goldberg), who has no first name and suffers from a tantrum-inducing affliction called Intermittent Explosive Disorder (IED).

The premise is intriguing. At its core, however, "Head Cases" proves to be an uninventive riff on that popular subgenre, the infantilized American male.

This evening's episode tells how the two protagonists get together. Workaholic, home-avoiding Jason has a nervous breakdown and part of his rehab toward becoming more of a mensch includes working with the socially inappropriate Shultz.

Like "The 40-Year-Old Virgin" and other descendants of Farrelly brothers' films, the story's central gag is the heroes' inability to emotionally grow up. Success with viewers depends on making these boy-men either irresistible sweethearts or outrageous bearers of truth.

"Head Cases" accomplishes neither goal. Its characters take fewer chances than the enfant terrible of "House," and the series seems fatally stuck between corny redemption and crass fun.

The show adopts the patented Fox posture of sneering at the rich, then swiftly retreats. Jason's downfall and comeback both occur in the pilot, and there's no relishing his humiliation, as we do with the Bluths every week on "Arrested Development."

Movie star O'Donnell's reluctance or inability to shift character doesn't help the cause. Despite an uncanny voice resemblance to Matthew Perry, O'Donnell hasn't the latter's skill at instantaneous haplessness or bliss. His Jason is merely bland.

That leaves the burden of humor and aw-shucks endearment to Goldberg, another good film actor. Unfortunately, his character also is ill-conceived and hard to grasp.

Shultz has IED minus any compensating genius. Although he repeatedly bails out Jason — a device bound to wear thin — his help consists of such tactics as secretly videotaping a philandering opponent. And how long can displays of temper be funny?

Instead of acknowledging its shallowness and going for laughs, "Head Cases" offers maudlin back stories that bid for our sympathy. Jason, for instance, has a long-suffering wife and the usual precocious and insightful child.

The show does revel in subplots about prostitution, sex addiction and infidelity. In David E. Kelley's hands, a hot mix of prurience and jurisprudence yielded "Boston Legal"; tonight's "Head Cases" isn't even worth a Wikipedia search for IED.

Kay McFadden: kmcfadden@seattletimes.com