Because of concerns about climate change, a lot of current environmentalist advocacy - including movies like An Inconvenient Truth" - concentrates on the dire results of burning fossil fuels. Joe Berlinger's "Crude," a thorough and impassioned new documentary, focuses its gaze on production rather than consumption. The film, which follows the fitful progress of a class-action lawsuit undertaken on behalf of the people of the Ecuadorean Amazon, is not about the unintended consequences of using petroleum. Instead, it examines the terrible, frequently unacknowledged costs of extracting oil from the ground. "Crude," in other words, investigates the local manifestations - cancer, contaminated water, cultural degradation - of a global problem. Even as "Crude" dwells on a single, relatively small slice of territory (about the size of Rhode Island), its action shifts from muddy villages in Amazonia to law offices and shareholders' meetings in the steel-and-glass cities of North America, drawing into its purview a motley cast of scientists, human rights crusaders, civil servants and international celebrities. Like almost every other recent documentary on a politically charged topic, "Crude" does not pretend to neutrality. Yet while Mr. Berlinger's sympathies clearly lie with the oddly matched pair of lawyers - Steven Donziger, a big, outgoing American, and Pablo Fajardo, a wiry, diffident Ecuadorean - who are consumed by the now 16-year-old suit against Chevron, he is fair-minded enough to include rebuttals from the company's executives and in-house environmental scientists. And since this is, in part, a courtroom drama, both sides have a chance to be heard.

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