John Trajer is a Post-doctoral Research Associate based at the Leverhulme Centre for Research on Slavery in War and The Dickson Poon School of Law. Within the Leverhulme Centre, John collaborates with colleagues from King’s College London and the University of Nottingham on research exploring the relationship between slavery and war in international law. He is a Co-Investigator on the project ‘Slavery in War: Transforming Legal Assistance for Survivors through an Identity-Led Approach’, led by Dr Rosana Garciandia.

Prior to joining King’s, John worked as a Research Fellow at the British Institute of International and Comparative Law, where his research focused on various aspects of the UK’s legal and policy framework on modern slavery. John has a PhD in Law and an LLM from the European University Institute in Florence, together with a BA from the University of Oxford and a joint MA from the universities of Göttingen and Groningen. During his doctoral studies, he held visiting positions at Vrije Universiteit Amsterdam, King’s College London, and the University of Michigan Law School. He is an active member of the Human Trafficking Research Network based at Ulster University.

Research Interests

• Slavery in war
• Modern slavery and human trafficking
• Conflict-related forced marriage
• International human rights law
• Migration and refugee law

John’s research examines how law conceptualises the relationship between slavery and war, focusing on the interaction between international criminal law, international humanitarian law, and international human rights law. As part of this broader research agenda, he is developing a strand of work on conflict-related forced marriage. This explores how armed groups use forced marriage to establish and govern slavery-type relationships, as well as the implications of these practices for legal doctrine and international accountability.

John is also involved in a collaborative project with Dr Rosana Garciandia on the representation of survivors’ identities and experiences of conflict-related slavery in legal and administrative processes. This project combines traditional socio-legal approaches with arts-based methods to develop guidelines for legal practitioners working with survivors of slavery in war.

John’s broader research interests include modern slavery and human trafficking, international migration and refugee law, international human rights law, and international criminal law. He is also interested in survivor-centred research methodologies and the legal dimensions of armed conflict.

Selected Publications

• Trajer, J. ‘Positive Obligations Reimagined: The Erosion of Causation in Findings of State Responsibility for Modern Slavery’ (forthcoming in V. Stoyanova and M. Andenæs eds., The Role of the Causal Inquiry under the European Convention on Human Rights, Cambridge University Press).
• Gauci, J.-P., Trajer, J., Stefanelli, J. et al. (2025) Immigration Detention and the Rule of Law: Safeguarding Principles. 2nd edn. London: British Institute of International and Comparative Law.
• Trajer, J. (2025) ‘Protecting Trafficked Migrants under European Law: Equality of Treatment versus Minimum Standards’, International Journal of Discrimination and the Law, 25(2).
• Magugliani, N., Trajer, J. and Gauci, J.-P. (2024) Assessing the Modern Slavery Impacts of the Nationality and Borders Act: One Year On. London: British Institute of International and Comparative Law. 

PURE profile

For more information on John's research, visit his research portal