When a giant US oil company goes up against a small Amazonian tribe, the outcome of the contest seems a foregone conclusion — and yet the strongest and most influential party does not always win. Such is the case of the legal battle between oil giant Occidental Petroleum and the indigenous Achuar tribe.

The Achuar live in the Peruvian Amazon rainforest; theirs is the last community situated on the banks of the Huasaga river before the border with Ecuador. The area is characterised by an incredible variety of plants and animals, and the indigenous people had lived in harmony with nature since time immemorial, with no contact with Western culture until just a few decades ago — until the arrival of oil companies.

In 2007, members of the Achuar tribe sued Occidental Petroleum, holding it responsible for severely polluting their territory, causing numerous deaths, premature births and health problems, and damaging the ecosystem on which they depend for their livelihood.

Today, after a lengthy legal dispute, the Achuar have obtained financial compensation from the oil company, the amount of which has not been disclosed. It is the first case in which a United States company has been sued in an American court for pollution caused in another country.

"A significant precedent has been set for future cases and has already been cited by other US courts," said Marco Simons, legal director of EarthRights International, the non-profit organisation that campaigns for the defence of human rights and the environment and represented the Achuar people in the lawsuit.

The compensation will be used for the development of health, education and nutrition projects, managed by a collective of five Achuar communities that depend on the Corrientes river, one of the most heavily polluted areas.

One of the plaintiffs, Adolfina Sandi, states that her two children, aged eleven and eight, died after drinking contaminated water from the river. "We did not know the impact of the pollution and the oil company never warned us of the danger," said Adolfina Sandi. "My son and daughter died vomiting blood."

Occidental Petroleum carried out drilling in Peru from 1971 to 2000, releasing enormous quantities of pollutants such as cadmium, lead and arsenic into the soil and groundwater without complying with international standards, according to a report by the NGO Amazon Watch.

A study conducted by Peru's Ministry of Health in 2006 found that many members of the communities analysed had blood cadmium levels above safe limits. The situation remains serious, yet the Achuar's victory against Occidental Petroleum represents a success — for the indigenous people, for the environment and for justice.