His Pants Are on Fire : If truth be told, ‘Liar Liar’ finds Jim Carrey returning to form and, once again, rising above the material.

Maybe Jim Carrey will never make a great film. Maybe he’s fated to star in substandard vehicles that couldn’t get to public access cable without his help. Maybe a lot of things, but the truth is, so what?

For as “Liar Liar” proves one more time, there is probably no more consistently funny performer working in film today. How much does it matter that this picture is an awkward mixture of Carrey’s brilliant physical comedy and a sappy plot about, hold on to your seats, the importance of being a good dad? Not a lot, because Carrey could turn Dr. Spock’s “Baby and Child Care” into a comic tornado.

Under the direction of Tom Shadyac, who’s become adept at rehabbing comics by reminding them they’re supposed to be funny (Eddie Murphy’s “The Nutty Professor” was his last outing), Carrey seems fully recovered from the abyss of “The Cable Guy,” willing and able to make people laugh.

His L.A. lawyer Fletcher Reede is a lot like Jerry Maguire before he saw the light, eager to say whatever it takes to get the job done and win cases. Intent on a partnership and with the slave-driving Miranda (Amanda Donohoe) as his boss, Fletcher never met a falsehood he wouldn’t embrace.

Of course, this kind of mendacity doesn’t make for family happiness. Fletcher’s long-suffering wife, Audrey (Maura Tierney), is now his ex-wife, happily involved with a milquetoast hospital administrator (Cary Elwes). And when son Max (Justin Cooper) is asked at school what his dad does for a living, the boy’s sad response is: “He’s a liar.”

Though this may sound like the set-up for a black comedy, that is one thing “Liar Liar” is not. Intent for some reason on giving the film heart, writers Paul Guay & Stephen Mazur have made sure to paint Fletcher as a great guy who really loves his son. He’s just too self-absorbed to get his priorities straight, especially with a big new case coming up involving a sexy adulteress (Jennifer Tilly) and the wealthy husband she wants to soak.

Then one night, after Fletcher has told yet another fib to his woebegone boy, Max turns the tables. He makes a birthday wish that for just one day his dad couldn’t tell a lie. And, because this is a movie after all, that wish comes immediately true and the real fun begins.

For Fletcher discovers soon enough what’s happened to him and ends up in a series of boggling battles with his own body as he tries to force himself to tell his usual lies. A scene with a blue pen he’d very much like to label as red is especially funny but the truth is when Carrey gets rolling everything he touches both verbally and physically leads to laughter.

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The king of body twists and rubbery contortions, with as much energy as James Brown in his “hardest working man in show business” phase, Carrey is equally adroit at turning his hand into a mock-monster called “The Claw” or disguising himself, improbable as it sounds, as a piece of luggage.

An impetuous imp capable of anything at all, Carrey also makes faces like no one alive and is in many ways the comic counterpart of horror legend Lon Chaney, the man who had a thousand of them. In one of “Liar Liar’s” defter moments, when son Max worries if he’ll suffer any ill effects from the boyish faces he likes to make, Fletcher reassures him with a calm, “In fact, some people make a good living that way.”

For Carrey’s co-stars, straight persons one and all, the hardest part of the job must be keeping from laughing. To emphasize that point, “Liar Liar” ends with a credit sequence punctuated by bloopers and outtakes from the production that are completely amusing.

For audiences, the hardest part of watching “Liar Liar” is marking time through the duller moments of exposition, wishing the film was as sharp overall as Carrey is himself. Still, as Bette Davis said to Paul Henreid at the close of the very different “Now, Voyager,” “Don’t let’s ask for the moon. We have the stars.”

* MPAA rating: PG-13, for sex-related humor and language. Times guidelines: par for the course for a Jim Carrey film.

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‘Liar Liar’

Jim Carrey: Fletcher Reede

Maura Tierney: Audrey Reede

Jennifer Tilly: Samantha Cole

Swoozie Kurtz: Dana Appleton

Amanda Donohoe: Miranda

Justin Cooper: Max Reede

Cary Elwes: Jerry

Imagine Entertainment presents a Brian Grazer production, released by Universal Pictures. Director Tom Shadyac. Producer Brian Grazer. Executive producers James D. Brubaker, Michael Bostick. Screenplay Paul Guay & Stephen Mazur. Cinematographer Russell Boyd. Editor Don Zimmerman. Costumes Judy L. Ruskin. Music John Debney. Production design Linda DeScenna. Art director Richard A. Toyon. Set decorator Ric McElvin. Running time: 1 hour, 26 minutes.

* In general release throughout Southern California.