FBI tried in vain to stop 'Deep Throat' film

Among the areas of the case file whited out is an interview with the star of the film, who at the time went by the name Linda Lovelace.

"Deep Throat" achieved fame unlike any pornographic film in history and become the most widely known adult film to reach a general audience. It was hugely profitable — made for about $25,000 and amassing hundreds of millions in receipts — and became a cultural buzzword.

Authorities have long said the movie was made with mafia money — and the FBI has linked the mob with porn over the years — but the file includes no mention of mob links.

Officials at every level of government tried to stop screenings and obscenity trials continued for years. But in the end, experts say, it represents the end of an era in which the government sought to stop the changing cultural tides.

Eugene Volokh, a law professor at UCLA, said the oddity of the scope of the investigation into "Deep Throat" is a reflection of very different times.

"Certainly today, with our broadly socially less restrictive attitude to most pornography and to sex more broadly it may seem odd that the government was spending so much effort on something like this," he said. "But attitudes back then were much different."