PARK CITY, Utah — It was shot for $25,000 US in just six days. Its male star was a film-crew member shoved in front of the camera as a last-minute replacement. Its director readily conceded it was not even a good movie.

Yet Deep Throat, www.xxxdeepthroat.com, was a cultural phenomenon whose theatrical grosses are estimated at $600 million, and it became an emblem of decadence for anti-pornography crusaders and the namesake for an informer who helped bring down a president.

Inside Deep Throat, a documentary that premiered this weekend at the Sundance Film Festival, examines the legacy of the 1972 flick, a forerunner of today’s hardcore adult-entertainment industry and a touchstone for obscenity laws.

Produced by Brian Grazer, whose films include Apollo 13 and A Beautiful Mind, Inside Deep Throat opens theatrically in New York City, Los Angeles, San Francisco, Boston and five other cities Feb. 11.

Grazer had been contemplating a film about Deep Throat star Linda Lovelace, who died in a 2002 car crash, but found the focus too narrow.

“I was less interested in the story of Linda Lovelace and more on the movie’s effect on popular culture,” Grazer said.

Porn movies previously had been made under the thin guise of sober sex-education films, but Deep Throat had an irreverent attitude.

Co-star Harry Reems, the lighting director on the film who stepped in after the original male lead did not work out, played a doctor helping a patient played by Lovelace cope with an unusual “condition” — a sexually sensitive area at the back of her throat.

“It was the first porn film to drop any pretence that it had educational value,” said Reems, now a real-estate broker in Park City. “There was no socially redeeming value, and so the word of mouth went out from people who saw it saying ‘This is just a comedy. It’s great. You’ve got to see this.'”

Its director, Jerry Damiano, said he did not think Deep Throat was a good movie, yet it overcame its preposterous story and cheesy production values.

After Deep Throat opened in Times Square, attention from Media critics and outraged conservatives turned it into a must-see movie. Arriving amid the women’s liberation movement, Deep Throat was also heralded as a celebration of female sexual fulfillment.

“It was the first time respectable middle-class women went to porn theatres,” social critic Camille Paglia says in an interview in Inside Deep Throat. Other cultural commentators appearing in the documentary include Norman Mailer, Ruth Westheimer, Gore Vidal, Erica Jong and Hugh Hefner.

Incorporating explicit oral-sex footage from the 1972 original, Inside Deep Throat has drawn an NC-17 rating, prohibiting people younger than 17 from seeing it.

Showing the notorious sex act was necessary for the documentary, said Inside Deep Throat directors Fenton Bailey and Randy Barbato, the filmmakers behind such acclaimed documentaries as Party Monster and The Eyes of Tammy Faye.

“There was no way we were going to make a film called Inside Deep Throat without including the act,” Barbato said. “Our film is not salacious or gratuitous. That scene needed to be in there.”

The movie was so ingrained in popular culture that Deep Throat became the nickname of the source who helped Washington Post reporters Bob Woodward and Carl Bernstein investigate the Watergate scandal that led to president Richard Nixon’s resignation.

Deep Throat was the object of repeated legal assaults by anti-smut forces. The most notable case was aimed at Reems, who was convicted of obscenity in 1976 and faced a potential five-year prison term. Celebrities including Jack Nicholson and Warren Beatty came to Reems’ defence, and the conviction was overturned.

What happened to its supposed $600 million in theatrical revenues is a mystery. Lovelace, Reems and director Damiano never got any of it.

Normal film-distribution channels were closed to Deep Throat because of its subject matter, so much of the distribution was handled by outfits linked to organized crime.

Theatres were visited daily by bagmen who collected the receipts in cash. There was no formal accounting and everyone involved skimmed off a piece of the action, Bailey and Barbato said.

“I suppose it’s kind of Hollywood-like,” Bailey said. “The money just disappears.”