Every dissident group needs its own martyr, and for the hipsters of the 1960s, the martyr was Lenny Bruce--Saint Lenny of the Nightclub, prophet with a potty mouth.

Bruce was a brilliant, funny, outrageous, obnoxious comedian who riffed on all the taboos of the era--race, sex, religion, politics--and who insisted on using the dirty words that comedians weren't allowed to utter in those days. For those sins, he was arrested all over the country, barred from working and generally hounded until he died of a drug overdose in 1966.

After that, he became a pop icon. Simon and Garfunkel sang about him: "I learned the truth from Lenny Bruce." There was a Broadway play and then a movie with Dustin Hoffman playing Lenny. Neither of those theatrical tributes was nearly as good as the documentary "Lenny Bruce: Swear to Tell the Truth," which premieres on HBO at 10:15 p.m.

This outstanding, Oscar-nominated, 94-minute movie, narrated by actor Robert De Niro, is full of rare footage of Bruce working in nightclubs, on TV and in a couple of cheesy movies that he wrote--films that his ex-wife aptly describes as "grade Z." There are also, appropriately, several newsreels of Bruce getting busted.

It's riveting stuff, but Bruce is nearly upstaged by his mother, the late Sally Marr, a former dance teacher and low-rung comedian. Interviewed while getting her bottle-blond hair cut and permed, Marr talked about how she took little Lenny to see strippers at a burlesque show when he was 12. She wanted him to grow up free of guilt, she says. She may have succeeded a little too well. The last time she talked to him, he was hiding behind his locked bedroom door, shooting smack.

Born Leonard Alfred Schneider, Bruce grew up on Long Island during the Depression, served in the Navy during World War II and then drifted into show biz. The clips of his early work show that he was pretty awful as a conventional comedian. In one clip, he wears what looks like a beanie and smacks himself idiotically in the head--a bit that makes Jerry Lewis look like Bertrand Russell.

Bruce paid his dues working the lowest rung of show business--emceeing at strip clubs. Nobody goes to those clubs to hear a comedian, so Bruce felt free to break out of the conventions of comedy. He stopped telling jokes and just started talking, delivering speed-fueled raps on whatever topic came to mind, trying to make the hipsters in the band laugh.

"The cheesier the dive, the freer Lenny was," De Niro says. The result was "a wild, free-form style of comedy."

In the early '50s, he married Harriet Lloyd, a gorgeous redheaded stripper who worked under the apt name "Hot Honey Harlow." They moved into a California bungalow with a white picket fence, but their lives were nothing like Ozzie and Harriet's. After work, they'd bring musicians and strippers home for orgies of booze, dope and sex.

They had a baby girl and then split up. The divorce inspired some of Bruce's more sensitive material: There's a clip of him on Steve Allen's show, singing a bittersweet song called "All Alone," with comic digressions about the pain of lost love. It's a surprisingly moving moment from a comedian who detested sentimentality.

But Bruce's best material came when he pushed the limits of what was then permissible. He satirized white paternalism in a bit called "How to Relax Your Colored Friends at Parties." And he mocked organized religion in a routine about Christ and Moses traveling to New York, only to discover the hypocrisy of their followers. There are brief clips from both of those routines in the documentary, but they fall a bit flat. The problem is that Bruce didn't work in one-liners. You really need to hear the whole shtick.

Today these riffs would be considered pretty tame, but back in the early '60s they were incendiary. Bruce became a hero to the hip and a target for prosecutors. He was busted in Philadelphia, San Francisco, Los Angeles and Chicago. The Philly bust was for possession of amphetamines; the rest were for obscenity.

"It's chic to arrest me," he says in one clip, looking even more hollow-eyed and beat than usual.

Arriving in England, he was met at the airport by bobbies who put him on the first plane home. By then, the only place where he could work was New York City, Gomorrah on the Hudson. And then, in April 1964, he was busted there, too.

He begged the judge to let him perform his act for the court: "Please don't lock up these words." The judge ordered a psychiatric evaluation, then sentenced Bruce to the maximum--four months in the workhouse.

Waiting for his appeal, broke, unemployed and obsessed with his court battles, Bruce hid out in his Hollywood home, writing legal papers and shooting dope. When he dropped dead with a needle in his arm, his electric typewriter was still humming. The last words he'd typed were "conspiracy to interfere with the Fourth Amendment."

Even in death, he was harassed by the cops, who escorted photographers into his bathroom, two by two, so they could shoot pictures of Bruce's bloated, naked corpse.

The documentary ends with that image. It's a powerful conclusion to an excellent film. But it would have helped to hear some analysis of Bruce's influence on American comedy and American culture.

That influence is deep and lasting. Bruce shattered forever the old barriers about what comedians could discuss and how they could discuss it. He led the way for such brilliant talents as George Carlin, Richard Pryor, Robin Williams and Chris Rock--as well as dozens of no-talent hacks who spew obscenities in unfunny "comedy" routines on cable TV every night.

Nowadays, if comedians offend us, we simply change the channel. It's so much more civilized than arresting them.

CAPTION: The comic whose satire shocked the nation is profiled tonight on HBO.

CAPTION: Lenny Bruce and his wife, Honey, with their daughter. Their divorce inspired some of the iconoclastic comedian's most poignant performances.