Legal Adviser and Director of the Office of International Standards and Legal Affairs 

Santiago Villalpando is the Legal Adviser and Director of the Office of International Standards and Legal Affairs since 2019. He has more than 25 years of professional experience in public international law, both in the United Nations system and in academia. He has previously served as Chief of the Treaty Section of the United Nations Office of Legal Affairs (2013-2018) and Registrar of the United Nations Dispute Tribunal in New York (2010-2011), and has worked at the Codification Division of the United Nations Office of Legal Affairs (2006-2010, 2011-2013), the International Court of Justice (2002-2006) and the International Criminal Tribunal for the former Yugoslavia (1996). He has participated in legal teams representing governments in international judicial proceedings at the International Court of Justice, and as adviser for international organizations.

Mr. Villalpando taught at numerous universities in the United States, Europe and Latin America, including the University of Geneva (1996-2001), Leiden University (2005-2006), New York University (2008-2014), the United Nations Regional Courses of International Law (2014-2018), the Graduate Institute of International and Development Studies (2019-2021), and the University of Paris 1 – La Sorbonne (2021). He has published four books, including L’Émergence de la Communauté Internationale dans la Responsabilité des États (which was awarded the 2004 Suzanne Bastid Prize of the French Society for International Law) and The Oxford Handbook of United Nations Treaties (co-edited with S. Chesterman, D. Malone and A. Ivanovic). His other publications in collective volumes and law journals cover topics such as international responsibility, the law of international organizations, international law-making, international adjudication, the law of treaties, international administrative law and international criminal law. He has served as editor of various international law journals, including as Senior Editor of the Leiden Journal of International Law (2004-2013). He is Associate Member of the Institut de Droit International since 2021.

A dual national of Argentina and Spain, Mr. Villalpando holds a PhD in International Law summa cum laude from the Graduate Institute of International and Development Studies (2003), as well as a Master’s in International Studies from the same Institute (1997) and a Laurea in Giurisprudenza summa cum laude from the Libera Università Internazionale degli Studi Sociali Guido Carli (1994).

• PhD summa cum laude, Graduate Institute of International and Development Studies (Geneva)
• Master's degree in International Law, Graduate Institute of International and Development Studies (Geneva)

• Law Clerck with the International Criminal Tribunal for the former Yugoslavia (1996)
• Legal Officer in the International Court of Justice (2002-2006)
• Legal Officer in the Codification Division in the Office of Legal Affairs in the United Nations Secretariat in New-York (2006-2011)
• Registrar of the United Nations Tribunal in New York (2011-2012)
• Chief of the Treaty Section in the Office of Legal Affairs in the United Nations (2013-2018)

• Oxford Handbook of United Nations Treaties (co-edited with S. Chesterman and D. Malone), Oxford, Oxford University Press, 2019.
• Handbook on the Internal Justice System at the United Nations (co-edited with H. Buss, Th. Fitschen, Th. Laker and Ch. Rohde), Turin, United Nations System Staff College, 2014.
• L’émergence de la communauté internationale dans la responsabilité internationale des États (Suzanne Bastid Prize), Paris-Genève, PUF-IUHEI, 2005.
• Réparer les crimes de l’histoire? Réponses du droit et de la justice (co-edited with L. Boisson de Chazournes and J.-F. Quéguiner), Bruxelles, Bruylant-Université de Bruxelles, 2004.
• « Gli strumenti della codificazione del diritto internazionale pubblico nell’età della codificazione light », in Atti del XXIII Convegno annuale della Società italiana di diritto internazionale, Milan, Giuffrè, 2019, pp. 259-278.
• « The Law of the International Civil Service » et « International Administrative Tribunals », in J.K. Coogan, I. Hurd, I. Johnstone (ed.), The Oxford Handbook of International Organizations, Oxford, OUP, 2017, pp. 1069-1084 et 1085-1103.
• « Codification Light: A New Trend of the Codification of International Law at the United Nations », Brazilian Yearbook of International Law, vol. VIII, 2013, pp. 117-155.
• « Functions of Depositaries » (in collaboration with F. Ouguergouz and J. Morgan-Foster), in Commentary to the Vienna Conventions on the Law of Treaties, Oxford University Press, 2011, pp. 1715-1757.
• « The Legal Dimension of the International Community: How Community Interests are Protected in International Law », European Journal of International Law, vol. 21/2, 2010, pp. 387-419.
• « Le codificateur, le juge et la responsabilité des États : interaction entre la CDI et la CIJ dans l’application des règles secondaires », Annuaire français de droit international, 2009, tome LV, pp. 39-61.