Get the message: The films that tackle issues

George Clooney's latest movie addresses political issues. Ben Dickenson says it's part of a growing trend

George Clooney indicts Senator Joseph McCarthy for crimes against television news. Jennifer Lopez and Martin Sheen lay siege to American corporations in Mexico. Sean Penn teams up with Steven Zaillian to parody corrupt right-wing politicians. Tim Robbins collaborates with Philip Noyce to re-interpret the term "terrorist". Fernando Meirelles, the inventor of City Of God, viscerally turns his lens on corporate misdemeanours in Africa. Is something political afoot in the world of cinema?

Good Night, and Good Luck, Clooney's superb 1950s newsroom drama, won't feature in any top 10 box office of the year, but it did receive critical praise at the London Film Festival in November. Bordertown, written and directed by Gregory Nava, and Zaillian's remake of the 1949 classic All The King's Men, are due next year. Both have attracted press attention in the US, with Lopez and Penn tipped for awards. Philip Noyce's Hot Stuff, also out in 2006, is the story of a South African freedom fighter, which Robbins has called one of the most exciting films he's worked on. Meanwhile, The Constant Gardener managed two months in the US box office top 10. These are movies of merit. They are also products of a political progression that began in the shadow of Ronald Reagan.

Ed Asner can currently be seen as Father Christmas on a special edition DVD of Elf. His long history of protest led to a bizarre press conference in 2003, where a Republican parent declared that her children would "never see a Communist Santa". Asner replied: "Santa does wear a red suit and re-distributes the toy wealth of the world." Such a confident rebuttal would never have passed Asner's lips during the 1980s, when he was sacked from the hit television show Lou Grant. In 1984, he led a protest to the US State Department over Reagan's involvement in the civil war in El Salvador. CBS - which produced Lou Grant - immediately threatened Asner's job. "You provide your pebble and roll it down the hill," he reflected, "in the hope of attracting more pebbles." Joining up with an avalanche was beyond Hollywood activists in the 1980s, and they retreated to wait for a saviour. "Hollywood is not, at its core, a radical town," comments Robbins. One man who knew that was Bill Clinton. He worked the communities of Hollywood progressives - the cover-all term for liberals through to radicals - and Hollywood businessmen alike. He had charisma to match a film-star, could speak in saccharine soundbites and loved Hollywood celebrity galas. Long-time Hollywood liberals like Warren Beatty were immediately convinced.

But, by 1999, hopes for Clinton's presidency had dissolved to despair. Clinton was primarily a facilitator of media business. The 1996 Telecommunications Act deregulated the media industry, giving corporate Hollywood a monopoly of cinema ownership and cable television; at the World Trade Organisation, Clinton negotiated first rights for US companies in Latin American broadcasting; and he gave himself "fast track" approval on trade deals for media firms. His reward was a guaranteed $8m (£4.5m) from every fundraising trip to Hollywood.

Dismayed by this business midwifery, Beatty responded with Bulworth (1999). Jay Billington Bulworth is a liberal politician reduced to a corporate lackey, who proclaims on national television that "the Democratic Party's got some shit to pay". After Clinton, a set of Hollywood radicals felt the same way. Robbins, Susan Sarandon, Sheen, Danny Glover and Penn found a new pole of political attraction on the streets of Seattle in November 1999. They were inspired by a dynamic, grassroots challenge to the World Trade Organisation, and by further protests in Melbourne, Prague and Genoa over the following 18 months.

Penn refused to talk about his film The Pledge at a July 2001 premiere at the Edinburgh Film Festival. Instead, he called for a "revolution" that would justify "brave young people putting their lives on the line", like the student Carlo Guiliani who had been killed by police at a protest in Genoa.

Films emerged that reflected the issues and spirit of the protests. Robbins's Cradle Will Rock presents poverty, collective action and a scathing portrait of the American bourgeoisie. Robbins persuaded the Disney executive Joe Roth to pay for the film, arguing that it wouldn't cost a lot to make and that it was an opportunity to market something to a politicised audience. Robbins manipulated Hollywood's profit motive to create a cinematic space.

Also entering this space was Erin Brockovich, in which the title character brings a corporation to its knees. Unlike Cradle Will Rock, it has little sense of a collective struggle, but there is a clear anti-corporate thread. John Q, Any Given Sunday, AntiTrust, The Insider, I * Huckabees, Bordertown and The Constant Gardener are in the same bracket. They are liberal films, replacing Beatty's flailing Bulworth with a renewed hero.

The arrival of George W Bush in office, September 11, and the war in Iraq only deepened this process of re-alignment. Noyce's The Quiet American articulates the dilemma subsequently faced by Hollywood progressives. Following a horrific explosion in Indo-China, the blood-spattered journalist Fowler is approached by local man, Hinh: "Sooner or later, Mr Fowler, one has to take sides, if one is to remain human." Fowler does take sides, against war and against Pyle, a "quiet American" exposed as a CIA operative. This sentiment dominated Hollywood during the Iraq war, with everyone from the politics-shy David Duchovny to the outspoken Sheen taking the side of peace and marching in the streets.

Artists United to Win Without War began life at a celebrity teach-in in 2002, officially supporting "the use of reasonable force" in Iraq.

Its members were less equivocal: Robbins and Sarandon told a New York protest in 2003, "our opposition to war should be our opposition to Halliburton"; Sheen called for the removal of the "dogs of war" from government; Penn visited Baghdad and said war was simply unjustifiable; and Glover marched with the anti-imperialist coalition Answer. This uneasy marriage of ideological differences continued until the presidential election of 2004. Artists United is affiliated to Move On, a large "non-partisan" coalition. During the 2004 election, Move On mounted a campaign of vote registration, and eye-catching television adverts that criticised the Bush election campaign.

In the 2000 election, Robbins, Sarandon and Glover had supported anti-globalisation Green candidate Ralph Nader. But, in 2004, Move On, reconciled with the Democratic Party through a series of policy deals, gave tacit support to John Kerry. Kerry is not in the company of Hollywood's new radicals. He supported the Iraq war and says he "believes in the freedom of business".

Yet, despite Bush's victory, the mood of opposition among Hollywood talent has not dwindled, as the recent spate of politicised film-making demonstrates. One film, The Assassination of Richard Nixon, summarises where many Hollywood progressives currently find themselves. It deals with contemporary social issues: distrusted presidents, terrorism, corporate power, racism and war. Penn took it on as a pet project.

The crucial speech in the film questions the global leaders of government and business: "Who are these men that keep us waiting at their feet? I will not go quietly." Neither, it seems, will Hollywood's new radicals.

Ben Dickenson's book 'Hollywood's New Radicalism' is published by IB Tauris at £14.99