There’s a moment in Michael Moore’s latest documentary, Sicko, that typifies everything that’s maddening and marvellous about this most provocative of film-makers. In this exposé of the ailing American health industry, the sequence in question centres on Jim Kenefick, the man behind Moorewatch. com, one of the leading antiMoore websites that began after the director won an Oscar for his 2003 gun-law film Bowling for Columbine. With his wife ill, Kenefick had already written on his blog that he was ready to shut down his site while he looked for money to pay for her medical bills – until he received an anonymous offer of $12,000.

It was only when Sickoscreened this year in Cannes, where Moore had received the Palme d’Or in 2004 for his previous film, Fahrenheit 9/11, that Kenefick discovered the identity of the donor. “I want him to know that it was meant with all the best intentions,” Moore told a packed Cannes press conference. “I even struggled a lot with [whether] I should film it. I had to ask myself, ‘Would you write this cheque if this wasn’t in the film?’ I decided this is what I would do, and what I should do, and this is the way I want Americans to live. I want us to start holding our hands out to people.”

In Moore’s mind this complements Sicko’s central message, which promotes “the we, not the me” as it lobbies for universal healthcare in the US. Yet this gesture can also be read as self-serving and opportunistic.

“There’s an argument to be made that Jim’s wife needed the money less than Michael Moore needed the publicity,” says Rick Caine, the co-director (with Debbie Melnyk) of Manufacturing Dissent, a documentary that sets out to put Moore under the spotlight. Due on DVD here just as Sickoreceives its British premiere at the LFF, it’s one of the more credible attempts of what Moore calls the “cottage industry” of the dozen or so films trying to “attack” him.

Meryl Streep on politics and passion

From The French Lieutenant’s Woman to a news reporter: how does Meryl Streep get her disguises so right

• Meryl Streep got the ball rolling

Related Internet Links

• London Film Festival

Background

• London just capital for directors

• Naomi Watts wows on opening night

• Tony Leung is in the mood for lust

• Pretty boy Brad Pitt grows up

• Brothers grim

Background

• Eastern Promises

• Viggo Mortensen joins the underworld's cast

• Michael Moore's healthy scepticism

• Are you kidding?

• Laura Linney, accidental screen queen

Related Internet Links

• LFF listings

Manufacturing Dissent offers several examples of how the 53-year-old Moore can distort the truth, such as in Bowling for Columbine, when he implies that the actor and National Rifle Association bigwig Charlton Heston insensitively attended a rally in Denver days after the Columbine school massacre when, according to Caine, it was “in North Carolina over a year later”.

Worse still, there’s the revelation that Moore secured an interview with Roger Smith, the chairman of General Motors, for his 1989 debut Roger & Me, which dealt with the collapse of the car industry in the director’s birthplace of Flint, Michigan. Excluding this exclusive from a film that was all about his mission to confront the man is hardly honest. Yet if you ask Moore to respond to accusations of misleading viewers he shirks the question.

“I think the record speaks for itself,” he says. “Eighteen years ago I made a film that said General Motors was a giant about to fall. At the time I was ridiculed. We now know what’s happening with the auto industry – General Motors is on the verge of bankruptcy. I made Bowling for Columbine, partially in the hopes that we would address how easy it is to get a gun in the States. Tragically, the school shootings continue.

I made Fahrenheit 9/11 and said we’d been led to war under false pretences... I would hope by now that I could catch a break.”

You can see his point, for even if Moore’s methods are questionable, his motives for fighting for the poor and disenfranchised aren’t. In Sicko, which sets out to examine just how health insurance companies set out to stiff their customers, in a truly heartbreaking scene he takes a group of sick Americans – including 9/11 firemen – to Cuba to find cheap medicine denied them in the US. Yet he just can’t help himself – as when he idealises the British health service. “We went into more than one British hospital,” he argues. “I’m comparing them with American hospitals, but I was surprised at how nice they were.”

Given how selective Moore is, you might argue – as his books Stupid White Men and Downsize This!testify – that he is now a polemicist of the people. He has certainly long since abandoned his journalistic background, which he began at the University of Michigan-Flint, where he edited the student newspaper, The Michigan Times. He went on to run the liberal publication Mother Jones.

Moore returned to Flint to make Roger & Me. Yet, as Manufacturing Dissent shows, Moore is not universally loved in his home town, not least because he helped to found a film festival in nearby Traverse City. In response, Flint started its own festival – often programming antiMoore films. “He could’ve given back to Flint,” says Melnyk. “It’s devastated.”

Yet after Fahrenheit 9/11 became the most successful documentary of all time, taking more than $100 million (£49 million) in America alone, nothing can derail the Moore bandwagon. While he refuses to be seen as the Democrats’ great white hope – “I’m a film-maker, I’m not a politician” – he remains optimistic for his country. “I believe that Americans at our core... have a good heart and a conscience.” Like his donation to Kenefick, perhaps? See Sicko and decide for yourself.

Sicko shows on Oct 24, 6pm, OWE2, and Oct 25, 1pm, OWE2.

Manufacturing Dissent is released on DVD on October 22 Reality bites: other top LFF documentaries

Hold Me Tight, Let Me Go

Kim Longinotto goes into a school for children who are traumatised or excluded from other schools.

In Prison My Whole Life

Should former Black Panther Mumia Abu-Jamal, convicted of killing a police officer in 1981, really be on Death Row?

State Legislature

Frederick Wiseman observes democracy in action in Idaho.

Explore Film

• Film Reviews

• DVD

• Oscars

• Bollywood

Editor's choice

• The top 10 fan versus band scuffles
• Mamma Mia! The first review
• Times critics' 20 best films for kids