Dr. Marcos A. Orellana is an expert in international law and the law on human rights and the environment. His practice as legal advisor has included work with United Nations agencies, governments and non-governmental organizations, including on wastes and chemicals issues at the Basel and Minamata conventions, the UN Environment Assembly and the Human Rights Council. He has intervened in cases before the Inter-American Court of Human Rights, the International Tribunal for the Law of the Sea, the International Centre for Settlement of Investment Disputes and the World Trade Organization's Appellate Body. His practice in the climate space includes representing the eight-nations Independent Association of Latin America and the Caribbean in the negotiations of the Paris Agreement on Climate Change, and serving as senior legal advisor to the Presidency of the 25th Conference of the Parties of the UN Framework Convention on Climate Change.

Professor Orellana has extensive experience working with civil society around the world on issues concerning global environmental justice. He was the inaugural director of the Environment and Human Rights Division at Human Rights Watch. Previously he directed the trade and the human rights programs at the Center for International Environmental Law, and he co-chaired the UN Environment Program's civil society forum.

Professor Orellana teaches International Environmental Law at the George Washington University School of Law and International Law at the American University Washington College of Law. Previously he has lectured in prominent universities around the world, including Melbourne, Pretoria, Geneva, and Guadalajara. He was a fellow at the University of Cambridge, visiting scholar with the Environmental Law Institute in Washington DC, and instructor professor of international law at the Universidad de Talca, Chile.