This engrossing blow by blow account covering three years in the decades-long class-action suit filed by 30,000 citizens of Ecuador against oil gaint Chevron provides a fascinating study of the tactics of both sides. We’re cheek by jowl with the passionately committed plaintiffs and Steven Donziger, their hawk-eyed, PR savvy New York attorney. And we’re caught short repeatedly by the remorseless corporate operatives who are hellbent on discrediting the human-rights crusaders.

At stake is the health of the Ecuadorian Amazon and the indigenous Cofán people. Texaco (acquired by Chevron in 2001) came to Ecuador in the late 60s to drill for oil. It is alleged that when the company left in the early 90s they concealed more than 1,000 toxic dumps and pumped poison into the rivers and rain forest. The implications of US imperialism in this struggle are as depressingly familiar as the plot of Avatar.

Documentarian Joe Berlinger’s ability to construct compelling, rounded drama from actual court proceedings is well known to admirers of his earlier Brother’s Keeper and Paradise Lost. Nobody will be surprised that it is the activists who are the more relaxed about affording Berlinger behind-the-scenes access and who talk frankly about their strategies. (We see Donziger coaching his Cofán witnesses to be more eloquently heartbreaking, urging celebrity Trudie Styler not to merely deplore the situation but to name-check Chevron at every opportunity.)

But Berlinger ensures that Chevron’s defenders are given their measure too – or given enough rope to move Village Voice’s Scott Foundas to compare their environmental spokeswoman to the villainous Tilda Swinton in Michael Clayton.

“A polished and haunting work of humanistic journalism, the film is passionate enough to follow its subjects in the ground-level combat of street demonstrations and office showdowns, and astute enough to understand the important roles a Vanity Fair article or a Trudie Styler endorsement can play in a cause. Crude is both a tribute to human-rights tenacity and a sobering account of the multinational-Moloch greed that can keep justice in limbo.” — Fernando Croce, Slant