Harvey Weinstein: Polanski has served his time and must be freed

It's a shocking way to treat a man who went through the Holocaust and his wife's murder

Roman Polanski is a man who cares deeply about his art and its place in this world. What happened to him on his incredible path is filled with tragedy, and most men would have collapsed. Instead, he became a great artist and continues to make great films. I was with him the day he won the Legion of Honour in France, which was a spectacular day. I remember the incredible love and affection that people have for him.

Now Thierry Frémaux, the director of the Cannes film festival, and I are calling on every US filmmaker to lobby against any move to bring Polanski back to the US, where he could face life in jail.

Whatever you think about the so-called crime, Polanski has served his time. A deal was made with the judge, and the deal is not being honoured. The theory going around is that the reason Switzerland cooperated and acted on a longstanding extradition order with the United States this time was because of their own troubles in the financial crisis.

I hope the US government acts swiftly because because film makers are looking for justice to be properly served. I will be organising the effort myself by emailing everybody I know to sign the petition. And I know that Thierry Fremaux has got hold of Nicolas Sarkozy.

We will have to speak to our leaders as well – particularly in California. I'm not too shy to go and talk to the Governor of California, Arnold Schwarzenegger, and to ask him once and for all to look at this. The problem is to do with the legal situation in the state. They are doing this because they want a circus, to make their toughness overt – and that is where I draw the line. This is the government of the United States not giving its word and recanting on a deal, and it is the government acting irresponsibly and criminally.

It is a shocking way to treat such a man. Polanski went through the Holocaust and the murder of his wife, Sharon Tate, by the Manson family. How do you go from the Holocaust to the Manson family with any sort of dignity? In those circumstances, most people could not contribute to art and make the kind of beautiful movies he continues to make.

I remember when I took Quentin Tarantino with me to a very private screening of the documentary Roman Polanski: Wanted and Desired, which shows some of the legal irregularities of his case.

I was involved by the film, and it was an amazing experience to see people weep at the end of it. Warren Beatty and Robert Evans were there, too, and you could feel the sense of injustice from these people who are part of Polanski's life. They know that, at heart, he is a humanist.

When Martin Scorsese was up to win best director for Gangs of New York, we faced Polanski and The Pianist. We were campaigning hard for Marty because he had never won best director, but when Marty lost to Roman, he turned to me and said: "I'm so happy right now. Of all the people in the world that I'd want to lose to, it's Roman. You have to understand that Polanski's films have influenced me as an artist all these years and his terrible political situation has been something we have all had to suffer through. We won because Roman won."

I think the reason we can all be on Polanski's side over this is not to do with what happened in 1977. It's to do with the fact that the punishment for what happened so many years ago had already been decided.

The deal was that if he spent time in prison, which he did pre-sentencing, his sentence would be commuted but when he came back to sentencing the judge went back on the deal. Forget about the Seventies era and whether this is excusable – this is a miscarriage of justice, and the government is making him a scapegoat.