We’re back folks, and what a lovely trip it was—at least, the parts we remember. Above you see three Japanese posters, each advertising Deep Throat and Deep Throat Part 2, which we gather ran as a double bill in Japan sometime in the mid-1970s. Deep Throat and its sequel starred Linda Lovelace as a woman whose clitoris was in her throat, and the first installment was the first truly mainstream porn film. 

In the U.S. this week, declassified FBI documents revealed that the U.S. government conducted a wide-ranging investigation into Gerard Damiano, director of the 1972 porn film Deep Throat. The heavily redacted documents showed that FBI agents across the nation were directed by top figures at the agency to conduct a campaign of harassment and intimidation against Deep Throat producers and distributors in a deliberate effort to stem the tide of sexual freedom that was sweeping the nation. Records show they seized prints of the film, and questioned everyone associated with its distribution, from delivery boys to theater managers.

Included in the stack of documents is an August 1973 letter stating that Damiano was being considered for prosecutorial immunity. The papers don’t say what crime exactly Damiano had committed, but at the time the film was thought to violate obscenity statutes and, because of an assumed link between porn and organized crime, various RICO charges might also have been considered. Ironically, the second-in-command at the FBI at that time was Mark Felt, who would soon play Deep Throat in real life when he became a secret source for Carl Bernstein and Bob Woodward during their Watergate investigation into Republican Party corruption. He adopted the moniker Deep Throat as his code name, and his real identity remained a mystery until he came forward in 2005.

Despite the FBI’s efforts, the tides of cultural change were too strong. What had been universally offensive just a generation before was seen as entertaining in 1972, and Deep Throat became the most popular x-rated film ever released, eventually earning more than 300 million dollars after an initial investment of around $25,000. At the height of the Deep Throat craze, the film was booked into mainstream cinemas and moviegoers attended packed showings without an iota of shame. Since then American culture has changed again, and, though consumption of pornography is so widespread it generates untold billions of dollars in yearly revenue, it has lost its aura of respectability and is virtually always consumed in private.