Mario Oyarzabal

The Legal Adviser to the Argentine Foreign Ministry

Member of the United Nations International Law Commission

Membre associé de l’Institut de Droit international

General Editor and co-founder of the Latin American and Caribbean Journal of International Law

Former Argentine Ambassador to the Netherlands and representative to the international organisations and tribunals in The Hague

United Nations Security Council — 2014

Ambassador Mario Oyarzábal is the Director General of International Legal Affairs and Legal Adviser of the Argentine Ministry of Foreign Affairs, International Trade and Worship since 2025, a position he also held between 2016 and 2020.

A career diplomat with the Argentine foreign service since 1997, Mario Oyarzábal served as Ambassador to the Kingdom of the Netherlands and Permanent Representative to the Organisation for the Prohibition of Chemical Weapons (OPCW) between 2020 and 2025, also representing Argentina before the International Court of Justice (ICJ), the Permanent Court of Arbitration (PCA), the International Criminal Court (ICC), the Hague Conference on Private International Law (HCCH) and the Common Fund for Commodities (CFC).

Previously, he was Deputy Permanent Representative of Argentina before the United Nations Security Council from 2013 to 2014 and Deputy Consul of Argentina in New York from 1998 to 2007. 

In 2015, Ambassador Oyarzábal was the Lead negotiator for Argentina on the United Nations General Assembly Resolution 69/319 on the Basic Principles on Sovereign Debt Restructuring Processes.

From 2016 to 2020, he was the Argentine Commissioner to the International Whaling Commission (IWC).

He has acted as Head of Delegation and Delegate of Argentina to meetings of the Sixth Committee of the United Nations General Assembly, the International Seabed Authority (ISA), the International Maritime Organization (IMO), the Hague Conference on Private International Law (HCCH), the International Institute for the Unification of Private Law (UNIDROIT), the United Nations Commission on International Trade Law (UNCITRAL) and the Seventh Inter-American Conference on Private International Law (CIDIP VII) among others.

In 2025, he was decorated Knight Grand Cross of the Order of Orange-Nassau by King Willem-Alexander of the Netherlands.

PRINCIPAL DIPLOMATIC ASSIGNMENTS

LEGAL POSITIONS

INTERNATIONAL LITIGATION

TEACHING

PROFESSIONAL AFFILIATIONS

EDUCATION

LANGUAGES

  • Spanish (native), English and French (fluent), Italian and Portuguese (read).