León Castellanos-Jankiewicz is Senior Researcher at the Asser Institute for International and European Law, and supervisor of the International Law Clinic on Access to Justice for Gun Violence at the University of Amsterdam Faculty of Law. His work focuses on the human rights implications of irresponsible arms trade.

Castellanos-Jankiewicz leads the project on 'Enabling Civil Society Efforts to Address the Misuse, Diversion and Abuse of Arms Exports in Latin America' within the Asser Institute, which was awarded a grant by the U.S. State Department (2023-2025).

He lectures regularly in universities across Europe in English, Spanish and French. Overtime, he has written for print and online publications including El País, NRC and Just Security. He is a listed expert in the Forum on the Arms Trade and sits on the Advisory Committee of Global Action on Gun Violence.

Previously, he was Max Weber Postdoctoral Fellow at the European University Institute. He has held visiting positions at the University of Gießen (2023), the University of Cambridge (2017) and Harvard Law School. He holds a PhD in International Law from the Geneva Graduate Institute.

Research areas

• Public International Law
• International Human Rights Law
• Arms trade
• Business and Human Rights
• History of International Law

• 'European Arms Manufacturers are Virtually Untouchable in Court. That has to Change', NRC, 8 August 2023 (in Dutch).
• 'El Blindaje de las Armerías Europeas', El País, 31 July 2023.
• 'The Armor of the European Arms Industry', El País, 31 July 2023.
• ‘La Frontera Blindada contra Migrantes’, El Sol de México, 25 March 2020.
• ‘La Amnistía Mexicana: Sus Tres Defectos’, Foreign Affairs Latinoamérica, 28 January 2020.
• ‘Matrimonio Igualitario en el Derecho Internacional’, Nexos, 19 June 2017.
• ‘Trump y la Migración Trasfronteriza’, Foreign Affairs Latinoamérica, 5 June 2017.