Police in Sydney closed down a public screening of banned US movie Ken Park because of its explicit depiction of sex and violence.
Ken Park has been effectively banned in Australia
The film, by Kids director Larry Clark, follows the lives of teenage skateboarders in a Californian suburb.
Australia's Office of Film and Literature Classification refused to issue it with a certificate - effectively banning it from cinemas across the country.
Police stepped in as 500 people attended a screening in the Sydney district of Balmain.
Superintendent Arthur Katsogiannis said police had to act after a written complaint from a member of the public.
"Our sole role was to ensure there was no screening of a refused classification film, we weren't here to disrupt any lawful activities nor any debate or censorship issues," he said.
After seizing the DVD on stage, police took the names of four people who admitted pressing the "play" button: critic Margaret Pomeranz, broadcaster Julie Rigg, academic Jane Mills, and film-maker Christina Andreef.
None of the four were charged or arrested, but if any charges are brought, they could face a maximum sentence of a year in prison.
Journalist David Marr said the screening was to highlight censorship of the film.
"This is what we used to call civil disobedience. This is a failed attempt to show a film a film that is banned in this country but which is seen in dozens of other countries," he said.
"The support tonight was extremely good, Australia is a tolerant country, and the decision to ban this film is an intolerant decision and it's not the real Australia at all."
Margaret Pomeranz admitted the film was shocking, but said people should be able to see it.
"Yes, it does portray confronting material, but it is within context," she said.
"It's sad, it's bleak, it's an art film - it would screen in arts cinemas for a discerning audience and that's all I'm asking for."
It was due to be shown at the Sydney Film Festival, but was dropped after the censors refused to classify it.
It was also due to be screened at the London Film Festival in November, but was pulled after Clark was arrested following a brawl with his UK distributor.
Metro Tartan refused to have anything more to do with the film after Clark punched its head, Hamish McAlpine, during an argument at a London hotel.