Year of election


  • Ambassador of the Argentine Republic to the Kingdom of the Netherlands
  • Member of the United Nations International Law Commission

Area(s) of Expertise

  • Public International Law
  • Private International Law
  • Human Rights Law
  • Nationality


Ambassador Mario Oyarzábal specialises in Public and Private International Law and their interaction. He is the Ambassador of the Argentine Republic to the Kingdom of the Netherlands and Permanent Representative to the Organization for the Prohibition of Chemical Weapons, representing also Argentina before the International Court of Justice, the International Criminal Court and the Hague Conference on Private International Law. He is also member of the United Nations International Law Commission, member of the Panel of Arbitrators and Conciliators of the International Centre for Settlement of Investment Disputes, as well as arbitrator and conciliator nominated under Art. 2 of Annexes V and VII of the United Nations Convention on the Law of the Sea.

A career diplomat, he previously served as The Legal Adviser to the Argentine Ministry of Foreign Affairs and as Deputy Permanent Representative of Argentina before the United Nations Security Council. He was also member of the Permanent Court of Arbitration, member of the International Humanitarian Fact-Finding Commission established by Additional Protocol I to the 1949 Geneva Conventions, member of the Committee on the Election of the Prosecutor of the International Criminal Court, and member of the Legal and Technical Commission of the International Seabed Authority. He has appeared as agent or counsel for Argentina before the International Court of Justice and the International Tribunal for the Law of the Sea. He has taught private and public international law at the Argentine universities of La Plata and Buenos Aires and at the Argentine Foreign Service Institute, among others.

Selected publications

  • Derecho internacional privado para diplomáticos, forthcoming, 2024
  • “The Influence of Public International Law upon Private International Law in History and Theory and in the Formation and Application of the Law”, Recueil des cours de l’Académie de droit international de La Haye, Vol. 428, 2023, pp. 129 et seq.
  • Derecho procesal transnacional (editor), Ábaco, Buenos Aires, 2012
  • “The Legal Regime of Antarctica”, Comité Maritime International Yearbook, Vol. 72, 2010, pp. 541 et seq.
  • “Il Protocollo aggiuntivo che modifica l’Accordo italo-argentino sulla cittadinanza”, Rivista di diritto internazionale, Vol. 90(3), 2007, pp. 749 et seq.
  • International Electronic Contracts”, University of Miami Inter-American Law Review, Vol. 35, 2004, pp. 499 et seq.
  • La nacionalidad argentina, La Ley, Buenos Aires, 2003
  • El Contrato de seguro multinacional, Ábaco, Buenos Aires, 1998
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