Two filmmakers behind a new documentary about John Lennon have credited their film to a 20-year campaign by a university professor to get FBI files on the former Beatle released.
Yoko Ono allowed the filmmakers new access to her husband's archive
The US Vs John Lennon focuses on 1972, when the Vietnam War was at its height, and Lennon led a campaign for peace with his famous "bed-ins" in the hope that the electorate would be persuaded not to vote for Nixon that year.
In response, wire-tapping, surveillance and a deportation order were put in place against Lennon by the administration. It was this deportation order - which was officially due to Lennon's conviction for possession of cannabis in London - that forms the basis of the film.
Co-director David Leaf told BBC World Service's On Screen programme that it took over 20 years of college professor Jonathan Wiener's efforts to get the 281 pages of FBI documents about the case out through the US Freedom Of Information act.
"Only with these documents were he and were we able to see the full picture of the US administration's efforts to silence Lennon," he said.
In late 1974, Rolling Stone magazine broke a small portion of the deportation story, but did not have all the access to the material.
Lennon claimed at the time that he was being deported because he was a "peacenik".
But as well as the documents uncovered by Professor Weiner, other new material shown in the film comes from Lennon's widow Yoko Ono.
"We really needed her to speak not only from her point of view as to what they were going through at the time, but to speak for John as well," said the film's other director, John Scheinfeld.
LENNON VS THE US
In 1971, Lennon plans national concert tour to coincide with 1972 Presidential election
Republican Strom Thurmond suggests "deportation would be a strategic counter-measure"
Proceedings begin on basis of Lennon's conviction for cannabis
Concert tour does not proceed
Deportation hearings give 60-day order to leave US; extended each time
Lennon given Green Card in 1975
"She also opened up the Lennon-Ono archives, so were able to include in the film a lot of material - film, videotape and photographic images that have not been seen before, as well as include three dozen John Lennon master recordings in the film."
This meant that the film contains new insight into Lennon's peace anthems from the time, such as Imagine and Give Peace A Chance.
Leaf said that crucial to making the film was giving context, and highlighting not only the court case or the Nixon administration, but everything that was happening in America at the time.
"We cast a very wide net for the best and most interesting material that would help us show what was going on in the country at that time," he said.
"We didn't want to stick with the same 10 shots you see on the news channels and most of the documentaries."
However, reviews of the film in the US have suggested that because the project is approved by Ono, it is a whitewash, and that it portrays Lennon as a saint.
It has also been criticised for not making any mention of Lennon's "lost weekend", the period in Lennon's life after the peace bed-ins in which he headed to Los Angeles and was involved in a number of drink-related incidents.
But Leaf and Scheinfeld said they had "told the story that we wanted to tell."
"This isn't supposed to be exhaustive and comprehensive - it's one story about one aspect of his life," said Leaf.
"We happen to think it's the most important story of his post-Beatles life."