BBC Four: What drew you to the story of the Weathermen?
Sam Green: I was always interested in the 1960s as a teenager. I'm 37, so I grew up in the 1980s, and how the 1960s became the 80s didn't make a lot of sense to me. As an adolescent there was a lot that appealed to me about the Weather Underground: the drama, the Bonnie and Clyde aspect of the story, these charismatic young kids trying to overthrow the government.

About five years ago I came across a book about the group that the US Government had put out in the 1970s. It had a section with all these mug shots. When I looked closely I realised that I recognised one of them - a guy who lives in the Bay Area, where I live. I called him up and asked, "You were in the Weather Underground?" He said, "You've found out about my secret life!" The more I talked to him, the more I saw it was very a complex story with a lot of moral ambiguity at its core. For me, it also raises a lot of provocative questions about justice and a person's responsibility for what their government is doing, and violence and the complex nature of social change. It started to snowball from there.

BBC Four: Was there much difficulty persuading former members to talk on camera?
SG: Everybody initially said it was a horrible idea and didn't want to cooperate. There wasn't a lot written on the group and what had been written was really negative. It's very easy to make them look ridiculous if you play down the [historical and social] context and play up the sex and crazy violence - they look like a bunch of kids who've gone nuts saying, "The revolution is going to happen". They were wary of that kind of treatment and felt the less said the better. It took a long time for Bill Siegel, who I made the film with, and myself to get them to warm to us. We had to impress upon them that we were going to take the story seriously, that we were a younger generation who was trying to come to terms with this moment in history and its impact on subsequent generations.

BBC Four: The death of Fred Hampton, the Black Panther, is a huge point in the film. Why is that so important in the Weather Underground story?
SG: I hadn't known a lot about Fred Hampton. But in talking to people I was trying to figure out what became the million dollar question: how did sheltered middle-class kids become "terrorists". These people weren't crazy so there had to be reasons why this transformation took place. I was struck that almost everybody pointed out the murder of Fred Hampton as a pivotal moment. Another thing that a lot of people mentioned was the Holocaust. Many Weather Underground members were Jewish and in 1969 the Holocaust was a pretty recent memory - it was closer to them then than they are to us now.

For them, the big lesson the world learned from the Holocaust was that you couldn't sit back if your country was doing horrific things - you had to act. They had an expression they used a lot, that they "refused to be good Germans". They really felt that America was like Germany in the 1930s. They knew Fred Hampton and had worked with him. After the cops came and murdered him while he was sleeping I think that a lot of people who were reluctant about going underground and waging armed struggle were pushed very decidedly in that direction.

BBC Four: You started the film in the late 1990s but finished it after 11 September 2001. Did that impact the tone of the film?
SG: I was in the middle of editing [on 11 September]. It was a horrific thing. In that moment it felt impossible to finish the film, the subject of political violence and political bombings was too charged to be able to address in any way. But after a while, when it became apparent what the reaction from this country was going to be, when I heard Bush's rhetoric that flattened everything out into this black and white moral language - good and evil, you're either with us or against us - I began to think that the film was even more relevant and resonant than it had been. I saw it as opportunity to indirectly raise some of the questions I felt needed to be asked in the context of what was happening now.

BBC Four: Have you had any criticism that the film is too sympathetic to the Weather Underground?
SG: I've had that but I've also had people saying it's too critical. I feel that if you're getting criticism from both sides in equal measure you've probably reached a good balance. I've often chuckled that the film got a good review in The Nation, which is a pretty liberal magazine, but also The Washington Times, which is one of the craziest, right-wing rags in the country. They both saw different things in it.

BBC Four: What's been the reaction of the former members of the group now they've seen it?
SG: It's not the film most of them would have made. A lot of them wanted it to have a lot more politics. I pointed out that we were making this for an audience who knew nothing about the subject. I think they would have made a film for people like themselves, who know all about SDS [Students for a Democratic Society], the Progressive Labour Party, anti-imperialism and [the influence of] Che Guevara. My goals were much more modest. I was always very careful not to overload somebody who doesn't know anything about this. But as time went by and they saw that the film was really getting out there in this country, it's done much better than anyone could have imagined, then they started to realise that we had been right in our calculations. They are all very supportive of the film.

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