IN the second of this week’s award-nominated films rooted in real-life clashes, Gus Van Sant tells the story of Harvey Milk, the first openly gay man to be voted into major public office in the United States.

Elected to the San Francisco Board of Supervisors in California in 1977, Milk was gunned down on November 27 1978, along with liberal Mayor George Moscone by Dan White, a fellow city supervisor who blamed an excess of junk food for his actions in what must have been the first case of mad cow disease. Milk and beef, it would seem, just didn’t get along.

Fie such flippancy, here is a story that resonates through time, not least in a week when another chain has been broken, and the first black President of the United States has been sworn in (twice).

Van Sant’s documentary-style biographical drama is solemn yet buoyant, a film of fervour, sorrow and joy that portrays Harvey Milk’s political activism as not only a victory for gay rights, but human rights too in pursuit of equality for all.

Where the last landmark movie of its kind, Nigel Finch’s Stonewall in 1995, fell short of its aspirations, here is a work of weight, substance, hope and romance too, not least on account of the performance of Sean Penn, a heavyweight Hollywood player who thankfully went back on his now-forgotten decision to give up acting.

Van Sant and screenplay writer Dustin Lance Black take up the life story of Milk (Penn) at the sobering moment when he is sat in the half light of his kitchen, tape-recording a valedictory, confessional message to be played only in the event of his assassination. Nine days later, he was indeed dead.

Van Sant dips in and out of that tape recording as a running commentary on the unfolding action that begins with Milk making a pass on 22-year-old Scott Smith (James Franco) in New York City on the eve of his 40th birthday.

They move to the supposedly more liberal San Francisco, where they open a camera shop but encounter prejudice from fellow shopkeepers, setting Milk on his path to break down the walls of discrimination. Lined up against him are Anita Bryant and Senator John Briggs, but Milk has a rallying zeal, bringing together a campaign team of Scott, lesbian manager Anne Kronenberg (Alison Pill) and persuasive drifter Cleve Jones (Emile Hirsch).

The relationship with Scott buckles under the strain of knock-backs in Milk’s political progress, catapulting Milk into a rocky relationship with high-maintenance Latino lover Jack (Diego Luna) and ultimately onwards to a collision course with the volatile, pent-up family man Dan Smith (Josh Brolin).

Franco smoulders like Heath Ledger in Brokeback Mountain, but the real fire sparks between Penn’s inexhaustible Milk and Brolin’s conservative, tortured White, and both performances are electric in their energy.

Penn, arguably the finest actor of his Brat Pack generation, hits a new peak, capturing the awkward mannerisms yet ever-positive demeanour of Milk, and when Van Sant mutates Penn’s face into the real Harvey Milk’s smiling mien, it is haunting indeed.

Not that Penn’s characterisation is the film’s primary triumph. More significantly, without turning Milk into a martyr, Van Sant achieves both a celebration of the man and the movement, his tone romantic and tragic and exuberant all at once.