So far, cases brought under the Alien Tort Statute (ATS) in U.S. courts have had little success in demonstrating that environmental harms violate international law, but that could soon change.

This week, plaintiffs in Arias v. Dyncorp, supported by a group of international environmental law scholars, filed a brief in which they made a powerful case for allowing ATS claims for cross-border environmental harms.  While courts have rejected ATS claims for environmental harms within a country’s borders, this is the first case to squarely address the issue of transboundary environmental harms—harms to the people and environment of one country resulting from activities occurring within a neighboring country.

The Dyncorp case deals with the cross-border human and environmental effects of herbicidal aerial spray operations conducted as part of Plan Colombia, a joint operation between the U.S. and Colombian governments to eradicate coca plantations within Colombia, including in areas near the Colombia-Ecuador border. The plaintiffs have submitted evidence that Dyncorp, a private company hired by the United States to conduct the spraying, failed to prevent the toxic chemicals it was spraying from reaching people’s communities and properties in Ecuador. The plaintiffs argue that Dyncorp’s actions have caused significant damage to the health, property, environment and livelihoods of thousands of Ecuadorians, and that this amounts to a violation of the international law requirement not to cause environmental harm in another country.

An ATS case requires a violation of a clear, universal and obligatory norm of customary international law – a rule that the international community generally agrees is a part of binding international law. TheDyncorp plaintiffs argue that international law requires states to exercise due diligence to prevent significant cross-border harms. This should be a pretty uncontroversial point; it is supported by multilateral treaties and UN declarations, decisions of the International Court of Justice and international arbitration tribunals, and many commentaries by legal scholars.

ERI filed an amicus brief supporting this position in 2002, and consulted with the plaintiffs’ attorneys in preparing their arguments in this latest round of briefing. The plaintiffs were also supported by a group of fourteen preeminent international environmental law professors and practitioners who filed an amicus brief affirming the existence of the international law norm.

This is an important case for protecting environmental and human rights under the ATS, and we’ll be watching its development closely.