Timing isn't usually an issue with biopics, but the fight over gay marriage and Proposition 8 in California puts "Milk" in an interesting light.

The movie is Gus Van Sant's absorbing biography of activist/politician Harvey Milk, assassinated in 1978 after a career as an organizer and canny politician who helped make San Francisco's Castro neighborhood safe for gays, and helped passed a gay rights' ordinance.

Milk is played by Sean Penn, and it's a technically impressive impersonation that also gets to the heart and soul of the subject, a closeted gay accountant from Manhattan who starts a new life in San Francisco, determined to finally make a difference at age 40.

It's not hard to find a cause worth fighting for. At the time, in the early 1970s, gay men were open targets for beatings and even murder, a climate tolerated by police and an indifferent political establishment.

Key early scenes find the pragmatic Milk finding ways to organize the gay community as an effective force, first by highlighting their financial contributions to Castro businesses. Profit and prosperity win hearts and minds, and establish the upstart, outspoken Milk as a de facto leader of the gay community - a fact underscored when the head of the local Teamsters union walks into Milk's storefront and asks him to enlist gay men in the union's ongoing boycott of Coors Brewing Co.

In low-key fashion, Penn and Van Sant skillfully show how Milk cultivates an appreciation and aptitude for smart politics - it isn't long before he's angling for a seat on the city's board of supervisors, itself a clever feat of persistence, electoral engineering and coalition building.

Milk could handle a bullhorn and motivate crowds, but Van Sant shows how good he was at helping his constituents find common cause with other groups, building alliances that helped get things done. As a supervisor, for instance, Milk endeared himself to the general public with an overdue pooper-scooper campaign.

Van Sant contrasts Milk's skill as a politician with his hard luck personal life - he has a succession of unsuccessful relationships (James Franco, Diego Luna) and these tend to have the feel of standard biopic domestic boilerplate (the movie runs a bit long).

Van Sant seems more interested in Milk's strange professional relationship with deeply conservative fellow supervisor Dan White (Josh Brolin), the man who will eventually kill him.

The movie depicts White as a talentless politician with a marginalized seat on the board, making an uneasy alliance with Milk in return for help on neighborhood issues (again highlighting Milk's skills as a pragmatist).

Milk backs off the agreement just days before the murder, raising the obvious suggestion of cause and effect, but Van Sant openly hints that White's rage ran much deeper, and had to do with unresolved feelings about his own sexuality (depicted as the reason Milk has such sympathy for White).

The event itself is presented with Van Sant's customary restraint - he is, after all, the same director who turned the Columbine massacre into a poetic meditation ("Elephant").

His bio of Milk is not a man-the-barricades fist-pumper that relies on swelling music and heroic shots. It's a quiet tribute to a guy who brought gay rights forward with common sense, hard work and a personal courage he found late in life. *

Produced by Dan Jinks, Bruce Cohen, directed by Gus Van Sant, written by Dustin Lance Black, music by Danny Elfman, distributed by Focus Features.