Dr León Castellanos-Jankiewicz

Senior researcher

Department:
Researchers
Research strand: In the public interest: accountability of the state and the prosecution of crimes
Main fields of interest: Business and Human Rights International Arms Control Law International Human Rights Law International Legal Theory Private International Law Public International Law

E-mail: L.Castellanos@asser.nl
Phone: +31 (0)70 3420 338

Profile

León Castellanos-Jankiewicz is Senior Researcher in International Law at the Asser Institute, and supervisor of the International Law Clinic on Access to Justice for Gun Violence at the University of Amsterdam Faculty of Law. He regularly advises governments on matters of international law, and has extensive experience working in projects involving interdisciplinary research, multistakeholder engagement and advocacy.

His research covers three broad fields. First, he is interested in arms trade and weapons transfer policy, in particular human rights safeguards, export controls, corporate accountability and due diligence. Second, he looks at the governance of global public goods through private law, including strategic litigation and supply chain resilience. Finally, he conducts research on legal history, focusing on the intersection of ideas between public and private international law.

He has been awarded competitive research grants by the Swiss National Science Foundation, the U.S. State Department and the Dutch Research Council (NWO), and has extensive teaching experience lecturing in English, Spanish and French. He frequently writes for print and online publications, including El País, NRC and Just Security and is a listed expert in the Forum on the Arms Trade. He sits on the Advisory Committee of Global Action on Gun Violence and is a regular commentator in the media.

Previously, he was Max Weber Postdoctoral Fellow at the European University Institute (2017-18) and has held visiting positions at the University of Giessen (2023; 2025), the University of Cambridge (2017) and Harvard Law School (2015-16). He is the inaugural recipient of the David D. Caron Prize of the American Society of International Law (2019) and holds a PhD in International Law from the Geneva Graduate Institute.

Publications

Edited volume

International Law and Time: Narratives and Techniques (2022) Berlin, Springer, co-editor with Klara Polackova Van Der Ploeg and Luca Pasquet. DOI: 10.1007/978-3-031-09465-1. ISBN: 978-3-031-09464-4.

Articles

'A Well-known Stranger: André Mandelstam — From Empire to Human Rights' (2025) 36(1) European Journal of International Law, 1-7 (with Momchil Milanov). DOI: 10.1093/ejil/chaf020.
'The Right to a Remedy for Wrongful European Arms Exports: Minding the Accountability Gap?' (2025) 56(3) The George Washington International Law Review, 277-294 (with Antonio Guzman Mutis). ISSN: 1534-9977.
‘Introduction to the Symposium on New Pathways Toward Supply Chain Accountability' ' (2024) 118 AJIL Unbound, 265-268 (with Tibisay Morgandi and Sergio Puig). DOI: 10.1017/aju.2024.49.
‘A New History for Human Rights: Conflict of Laws as Adjacent Possibility’ (2024) 26(2) Journal of the History of International Law / Revue d'histoire du droit international, 119-160. Open access. DOI: 10.1163/15718050-bja10095.
‘Introduction: Historical Memory in Post-Communist Europe and the Rule of Law’ (2020) 5 European Papers, 95-106 (with Grazyna Baranowska). DOI: 10.15166/2499-8249/386.
‘Minority Rights Petitions: League of Nations’, Max Planck Encyclopedia of International Procedural Law (EiPro), Oxford, Oxford University Press (2020).
‘Security Council Listing Procedures and Human Rights’ (2013) 1(2) Revista In Jure Anáhuac Mayab, 117-142. ISSN 2007-6045.
‘Causation and International Shared Responsibility’ (2012) ACIL Research Paper No. 2012/07 (SHARES Series), Amsterdam Center for International Law.

Special issues and symposia

'New Pathways Toward Supply Chain Accountability' (2024) 118 AJIL Unbound, 265-302 (Symposium co-editor with Tibisay Morgandi and Sergio Puig). ISSN: 2398-7723.
‘Decolonization and Human Rights—The Dutch Case’, Verfassungsblog, Jan/Feb 2022 (Symposium co-editor with Wiebe Hommes). ISSN: 2366-7044.
‘Historical Memory in Post-Communist Europe and the Rule of Law’ (2020) 5 European Papers (Special Issue co-editor with Grazyna Baranowska). ISSN: 2499-8249.

Book chapters

'Minorities, Refugees and Human Rights', in Robert Kolb and Momchil Milanov (eds), The Cambridge History of International Law, Vol. X: International Law at the Time of the League of Nations (1920-1945), Randall Lesaffer, general editor, Cambridge University Press (2025, with Momchil Milanov). DOI: https://doi.org/10.1017/9781108633963.018.
'Mexico v Smith & Wesson: Jurisdictional Aspects', in Miguel Ángel Reyes Moncayo and Wilma Gandoy (eds), El negocio de la letalidad: el tráfico de armas a México, Mexico, Secretaría de Relaciones Exteriores (2024). ISBN: 978-607-446-342-2.
‘Overlooking Continuity: National Minorities and ‘Timeless’ Human Rights’ in Klara Polackova Van Der Ploeg, Luca Pasquet and León Castellanos-Jankiewicz (eds), International Law and Time: Narratives and Techniques, Berlin, Springer (2022). DOI: 10.1007/978-3-031-09465-1_20.
‘Negotiating Equality: Minority Protection in the Versailles Settlement’ (2019) in Michel Erpelding, Burkhard Hess and Hélène Ruiz Fabri (eds), Peace Through Law: The Versailles Peace Treaty and Dispute Settlement after World War I, Nomos/Hart. DOI: 10.5771/9783845299167.
‘Serious Breaches of Peremptory Norms’ (2014) in André Nollkaemper and Ilias Plakokefalos (eds), Principles of Shared Responsibility in International Law: An Appraisal of the State of the Art, Cambridge, Cambridge University Press, pp 284-311 (with Eric Wyler). DOI: 10.17/CBO9781139940009.
‘State Responsibility and International Crimes’ (2010) in William Schabas and Nadia Bernaz (eds), Routledge Handbook of International Criminal Law, Oxford, Routledge, pp 385-406 (with Eric Wyler). ISBN: 9780415524506.

Reports and Policy Briefs

'Combating illicit firearms trafficking in Latin America and the Caribbean. Towards a regional roadmap', Global Initiative against Transnational Organized Crime, August 2025 (with Paddy Ginn, Cecilia Farfán-Méndez and Romain Le Cour Grandmaison).
'Transparency in European Arms Exports: Access to Information and Accountability', Jennifer Bunnik, Ana Gobillon, Jiaxin Li, Jan Melck and Zia Wendt, University of Amsterdam Law Clinic on Access to Justice for Wrongful Arms Transfers (Supervisor), June 30, 2025. ISBN: 9789067043748.
'Ensuring access to justice for gun violence: seeking accountability for European arms exports', Jasmijn van Dijk, Felix Hartner, Viktoria Schmidt and Nada Ben Yahia and León Castellanos-Jankiewicz (Supervisor), University of Amsterdam International Law Clinic on Access to Justice for Gun Violence, July 28, 2023. ISBN: 9789067043878.

Professional blog posts

'SCOTUS Rules for Gun Manufacturers in Mexico Suit But Denies Blanker Immunity', Just Security, June 23, 2025. Republished with permission in Transnational Litigation Blog, June 25, 2025.
'The Private is Political: Conflict of Laws and a New History of Human Rights. An Interview with León Castellanos-Jankiewicz', Völkerrechtsblog, September 30, 2024. DOI: 10.17176/20241001-005849-0 (with Hendrik Simon).
'Dutch Court Halts F-35 Aircraft Deliveries for Israel', Verfassungsblog, February 14, 2024. DOI: 10.59704/4ef8e6e2634877d7.
'The Sovereignty of Sharing: An Interview with Michael Fakhri (Part I)', Opinio Juris, July 6, 2023 (with Carl E. Lewis and Melanie Schneider).
'The Sovereignty of Sharing: An Interview with Michael Fakhri (Part II)', Opinio Juris, July 6, 2023 (with Carl E. Lewis and Melanie Schneider).
'Including the Arms Sector in the EU Corporate Due Diligence Directive', Verfassungsblog, May 19, 2023 (with Melanie Schneider). DOI: 10.17176/20230519-140428-0.
'Applying Mexican Law in U.S. Courts? Mexico v Smith & Wesson', Conflictoflaws.net, April 8, 2023.
'Mexico Appeals in Case Against Gun Manufacturers', Just Security, April 4, 2023.
'Empresas de armas y derechos humanos: México solicita Opinión Consultiva a la Corte Interamericana', Agenda Estado de Derecho, March 3, 2023.
'Mexico v. Smith & Wesson: Judge Dismisses Complaint Citing PLCAA and Standing Issues', ASIL Insights, Volume 26, Issue 15, December 20, 2022 (with Leila Nadya Sadat).
'Ensuring Access to Courts for Gun Victims: The Case for Repealing PLCAA', Just Security, 8 September 2022 (with Kaya van der Horst).
‘Decolonization and Human Rights—The Dutch Case: An Introduction’, Verfassungsblog, 24 January 2022 (with Wiebe Hommes), DOI: 10.17176/20220124-180324-0.
‘Mexico v. Smith & Wesson: U.S. Court Duel Over Extraterritorial Legal Issues Looms with Motion to Dismiss’, Just Security, 14 December 2021.
‘US Border Closure Breaches International Refugee Law’, Opinio Juris, COVID-19 Symposium edited by Barrie Sander and Jason Rudall, 3 April 2020.
‘Mexico’s Amnesty Proposal: An Instrument of Transitional Justice?’, Just Security, 4 March 2020.
‘The Lauterpacht Lectures 2017: Towards a Global Private Law?’, Cambridge International Law Journal Blog, 29 August 2017.
‘Human Rights and the End of Status’, Humanity Journal Blog, 27 April 2016.

Conference proceedings (selected)

‘International Conference on Improving Supply Chain Accountability for Arms Exports’, 13-14 May 2024, Asser Institute for International and European Law, The Hague (convener).
‘Accountability for Gun Violence: What's Next In Mexico's Case Against Gun Manufacturers?', online webinar, 29 February 2024, Forum of the Arms Trade (co-convener with Jeff Abramson).
'The Monroe Doctrine: History, Interpretations, Legacy', 30 November-2 December 2023, Goethe University Frankfurt, Germany (co-convener with Dr. Raphaël Cahen and Dr. Hendrik Simon).
'New Public and Private Pathways towards Supply Chain Accountability', 17 November 2023, research workshop, Asser Institute for International and European Law, The Hague (co-convener with Dr. Tibisay Morgandi).
'Transnational Civil Litigation and Corporate Liability: Mexico v Smith & Wesson', expert panel discussion hosted by the Embassy of Mexico to the Kingdom of the Netherlands on 2 May 2022 (co-convener with Prof. Thilo Marauhn).
‘Truth and Transitional Justice in Latin America’, online Expert Panel on Missing Persons and Memory Governance, 24 September 2020 (convener).
'National Political Communities and International Institutions', Multidisciplinary Research Workshop, Max Weber Programme for Postdoctoral Studies, European University Institute, Italy, 30 August 2018 (co-convener with Dr Angelo Caglioti and Dr Madeleine Dungy).
‘Negotiating Equality: Minority Protection in the Versailles Settlement’, Max Planck Institute Luxembourg, conference on Peace Through Law: The Versailles Peace Treaty and dispute settlement after WWI, 6 December 2017 (presenter).