So severe is the environmental damage [at Lago Agrio, on the fringes of the Ecuadorian Amazon] that experts have called it an Amazon Chernobyl". But the people of Lago Agrio and its surrounding area have been fighting back. Sixteen years ago, 30,000 Ecuadorians began legal action against the US oil company - now owned by Chevron - they hold responsible. This week, while both sides await the verdict, a fly-on-the-wall documentary about the case goes on release in Britain. Directed by Joe Berlinger ... "Crude" tells a story [that] began when Steve Donziger, a lawyer acting for the Ecuadorians, arrived at the film-maker's office. "The story the lawyer told me was indeed shocking," said Berlinger. Within a few days of Berlinger's trip to Ecuador, he realised that the case was virtually demanding to be made into a film. "I noticed a group of indigenous people sitting by the riverbank, preparing a meal by an open fire using processed tuna fish from a big industrial-sized can. They were eating this canned tuna because the fish that swam in their river, which had fed these proud people for millennia, were dead." "Crude" is a head-on culture clash bursting with strong personalities where brash US lawyers on both sides are at loggerheads, and Ecuador's indigenous - incongruous in New York with their traditional dress and warpaint - are carefully coached to fight their case in a foreign system.