Yusuf's previous positions include: Legal Adviser and Director of the Office of International Standards and Legal Affairs for UNESCO from March 2001 to January 2009, Legal Advisor (1994–1998) and Assistant Director General for African Affairs, United Nations Industrial Development Organization (UNIDO), Vienna (1998–2001), Representative and Head of the New York office of the United Nations Conference on Trade and Development (UNCTAD) (1992–1994) and Chief of the Legal Policies Service of UNCTAD (1987–1992), Lecturer in law at the Somali National University (1974–1981) and at the University of Geneva (1981–1983), and Somali delegate to the Third United Nations Conference on the Law of the Sea (1975–1980). He has also been guest professor and lecturer at a number of universities and institutes in Switzerland, Italy, Greece and France.
Yusuf was elected to the Institut de droit international in 1999 and is currently a member. He is the founder and General Editor of the African Yearbook of International Law. Yusuf is also one of the founders of the African Foundation for International Law, as well as the chairperson of its executive committee. In addition, Yusuf has authored several books and numerous articles on various aspects of international law as well as articles and op-ed pieces in newspapers on current Northeast African and Somali affairs. He is a member of the editorial advisory board of the Asian Yearbook of International Law, and a member of the Thessaloniki Institute of Public International Law and International Relations curatorium.[3] He also previously served as a judge ad hoc at the International Court of Justice.[4]
Panafricanisme et droit international, Académie de droit international de La Haye, hors collection, 2017.
Intellectual Property and International Trade: The Trips Agreement (ed. with C. Correa), 3rd Edition (Kluwer Law International, 2016).
African Yearbook of International Law, (Founder and General Editor), (Vols. 1-21), 1993–2016, Kluwer Law International and Nijhoff Publishers (London, The Hague, Boston).
Pan-Africanism and International Law, Brill, Nijhoff, 2014.
L’Union africaine: cadre juridique et institutionnel. Manuel sur l’organisation panafricaine (ed. with F. Ouguergouz), Paris: Pedone, 2013.
The African Union: Legal and Institutional Framework. A Manual on the Pan-African Organization (ed. with F. Ouguergouz), Leiden: Nijhoff, 2012.
Standard setting in UNESCO/L’action normative à l’UNESCO (ed.), Paris: UNESCO Publishing and Leiden: Nijhoff, 2007.
Intellectual Property and International Trade: the TRIPS Agreement (ed. with C. Correa), The Hague: Kluwer Law International, 1st edition, 1998, 2nd edition, 2007.
International Technology Transfer: The Origins and Aftermath of the United Nations Negotiations on a Draft Code of Conduct (ed. with S.J. Patel and P. Roffe), The Hague: Kluwer Law International, 2001.
Legal Aspects of Trade Preferences for Developing States: A study in the Influence of Development Needs on the Evolution of International Law, The Hague: Nijhoff Publishers, 1982.
