Among many other clients and cases, he was Counsel and Advocate for Nicaragua in the historic case of Nicaragua v. United States of America (1984-1986), regarding the illegal use of force in international relations, for Uruguay in the case of Argentina v. Uruguay (2006-2010), concerning international environmental protection and sustainable development, for the Philippines in Philippines v. China (2013-2016) over maritime jurisdiction and entitlements in the South China Sea; and most recently for Mauritius (2017-2019) in advisory proceedings regarding the decolonization of the Chagos Archipelago.
He has extensive experience representing Sovereign States in land and maritime boundary disputes with neighboring States, including Nicaragua against Colombia in the International Court of Justice (2007-2012); Nicaragua against Costa Rica (ICJ, 2014-2018) and Somalia against Kenya (ICJ, 2014-present); Bangladesh against Myanmar before the International Tribunal on the Law of the Sea (2009-2012); Ghana against Cote d’Ivoire (ITLOS, 2014-2017); and in arbitrations under the United Nations Convention on the Law of the Sea, Mauritius against the United Kingdom (2011-2015); Bangladesh against India (2009-2014) and Guyana against Suriname (2004-2007). He served as Mediator, appointed by the Secretary General of the Organization of American States, in the land and maritime boundary dispute between Guatemala and Belize (2000-2002).
He has represented Sovereign States in disputes over transboundary environmental harm ‒ including Ecuador against Columbia, Uruguay against Argentina, and Nicaragua against Costa Rica ‒ all before the International Court of Justice.
He has also represented Sovereign States in disputes with foreign investors in the world’s principal arbitral forums, including the International Centre for the Settlement of Investment Disputes (ICSID), the International Chamber of Commerce (ICC), the Permanent Court of Arbitration (PCA), and the Stockholm Chamber of Commerce (SCC), where his clients have included Ecuador, Guyana, Mauritius, Nicaragua, the Philippines, Uruguay and Venezuela. He was lead counsel to Uruguay in its landmark defense of its tobacco control regulations against a challenge brought by Philip Morris.
He has nearly four decades of experience representing Sovereign States before the courts of the United States, and is one of the leading experts on litigation under the Foreign Sovereign Immunities Act, having defended such clients as Thailand, Chile, Kenya, Tanzania, Venezuela, Liberia, Bolivia, Ecuador, Nicaragua, the Philippines and Guyana.
Specialization in the representation of Sovereign States before:
- the International Court of Justice in The Hague
- the International Tribunal on the Law of The Sea
- the International Centre for the Settlement of Investment Disputes (ICSID)
- the International Chamber of Commerce (ICC)
- other International Arbitration Bodies in Latin America, Europe, Asia and the United States
- Federal and State Courts in the United States