Mario Oyarzabal

Oyarzabal has represented the Argentine Republic on two occasions before the International Court of Justice in the case of the Uruguay River pulp mill dispute between Argentina and Uruguay as legal counsel, and in the Advisory Opinion on the Legal Consequences of the 1965 Separation of the Chagos Archipelago from Mauritius in as agent in 2019.

Mario Oyarzabal (Azul, February 4, 1969) is an Argentine jurist and diplomat.

Oyarzabal graduated in 1991 as a lawyer and in 1992 as notary public at the National University of La Plata.

He entered the Argentine Foreign Service Institute graduating in 1996.

Oyarzabal joined the Argentine Foreign Service in 1997.

He served in the Department of Parliamentary Affairs of the Foreign Ministry (1997-1998), the Consulate General in New York (1998-2004 and 2005-2007), the Legal Department of the Foreign Ministry (2007-2011 and 2016-2020), the Permanent Mission to the United Nations (2011-2016), and the Argentinian Embassy in the Netherlands (since 2020).

In 2005, he obtained a Master of Laws (LLM) from Harvard University.

In 2011, Oyarzabal was a legal advisor in the first Advisory Opinion of the Seabed Disputes Chamber of the International Tribunal for the Law of the Sea, on the responsibilities and obligations of States sponsoring persons and entities concerning activities in the Area.

He has taught courses at The Hague Academy of International Law in 2012 and 2020, and is the author of numerous publications in specialized journals in Argentina and abroad.

In 2021, Oyarzabal was elected member of the United Nations International Law Commission for the period 2023-2027.

In 2023, Oyarzabal was elected Associate member of the Institute of International Law at its 81st Session of Angers (France).

Additionally, Oyarzabal has served as a member of the Legal and Technical Commission of the International Seabed Authority (2012-2013), the International Humanitarian Fact Finding Commission established by the 1949 Geneva Conventions (2017-2021), and the Committee for the Selection of the Prosecutor of the International Criminal Court (2019-2020).

Oyarzabal has taught international law at the University of La Plata and the University of Buenos Aires, among others.

He was deputy permanent representative to the United Nations Security Council between 2013 and 2014, and Director General of the Legal Department and The Legal Adviser of the Foreign Ministry between 2016 and 2020.

Oyarzabal is a generalist public and private international lawyer.

In addition, he was an arbitrator and conciliator of the International Center for Settlement of Investment Disputes (2016-2022) and a member of the Permanent Court of Arbitration (2019-2022).

Oyarzabal is an arbitrator and conciliator appointed under Annexes V and VII of the United Nations Convention on the Law of the Sea since 2017.

In 2018, Oyarzabal was promoted to the rank of Ambassador Extraordinary and Plenipotentiary with the approval of the National Senate.

The following year, he was appointed Ambassador to the Netherlands by Decree No. 793/2019 of then-President Mauricio Macri, assuming functions during the administration of President Alberto Fernández.

He has been the ambassador of Argentina to the Netherlands and a permanent representative for the Organization for the Prohibition of Chemical Weapons since 2020.

He is also Permanent Representative to the Organization for the Prohibition of Chemical Weapons, and represents Argentina before the International Court of Justice, the International Criminal Court, the Hague Conference on Private International Law, and the Common Fund for Commodities of which he became Chairman of the Governing Council (2020-2022).

In 2020, he taught a course at The Hague Academy of International Law on "The Influence of Public International Law on Private International Law in History and Theory and in the Formation and Application of Law".

He is the author of 4 books and more than 50 contributions in collective works and academic articles published in legal journals such as the Rivista di diritto internazionale, Rabels Zeitschrift für ausländisches und internationales Privatrecht, Uniform Law Review, Revista Española de Derecho Internacional, University of Miami Inter -American Law Review, Revista de Informação Legislativa; and publications such as the Encyclopedia of Private International Law and the Argentine Yearbook of International Law.