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PhD Thesis

The Regulation of Intelligence Activities under International Law

Defence date: 23 November 2020

Examining Board:
Prof. Sarah Nouwen (European University Institute), Chair
Prof. Martin Scheinin  (European University Institute), Supervisor
Prof. Olivier de Frouville (Université Paris II Panthéon-Assas), Cosupervisor
Prof. Anne van Aaken (Universität Hamburg)


Espionage has existed since the birth of humanity but neither it nor its modern forms (intelligence activities) have ever been explicitly addressed in international law. Despite this absence of direct normative regulation, the international legal order has managed to constrain states’ freedom in intelligence matters. This paradoxical state of affairs thus triggers theoretical and empirical research questions aimed at understanding how intelligence activities are regulated under international law.

This thesis theorises and models the regulation of intelligence activities under international law. Regulation is conducted by the international legal order, following a layered process: ethics and legality; enforcement of state responsibility; and effective accountability. In short, effective regulation leads to effective accountability, which itself leads to state compliance. As a result, we can now predict and explain state behaviour in intelligence matters as follows: the expectation that a state will comply with international law in its intelligence activities is equal to the likelihood of international legal accountability.

The thesis first demonstrates through doctrinal analysis that intelligence activities are indirectly but comprehensively addressed by international law. Breaches of applicable international rules thus lead to the engagement of state responsibility, and the concept of international legal accountability allows us to understand how legality is enforced in the international legal order. The thesis then adopts a behavioural approach to international law to theorise and model the role of state accountability in the regulatory process. Theoretical applications of experimental findings, interpreted through the lens of regulatory theory, provide the theoretical framework necessary to empirically identify the influence of legal and extra-legal factors on state decision-making in intelligence matters, and thus on state compliance with international law. Several case-studies empirically confirm the theories and model thus developed. Their findings also highlight the path towards a more systematic enforcement of international legality and an increase in state compliance. Finally, the thesis theoretically and empirically confirms that compliance with international law serves the national security interests of states. 

Academic Publications

Peer-reviewed Articles

Duroy, S. (2021). State compliance with international law in intelligence matters: A behavioural approachJournal of International Dispute Settlement.   (preprint:

Duroy, S. (2020). Chronique des constatations des comités conventionnels des Nations Unies: Comité contre la Torture, M. Z. c. Belgique, 2 août 2019, Communication No 813/2017. Revue Droits Fondamentaux, 18, 11–14.

Book Chapters

Duroy, S. (2022). Black sites. Forthcoming in C. Binder, M. Nowak, J. A. Hofbauer, & P. Janig (Eds.), Elgar Encyclopedia of Human Rights. Edward Elgar Publishing. (preprint:

Duroy, S. (2021). The regulation of intelligence cooperation under international law: A compliance-based theorization. In A. Vedaschi & K. L. Scheppele (Eds.), 9/11 and the rise of global anti-terrorism law: How the UN Security Council rules the world. Cambridge University Press.

Duroy, S. (2020). Remedying violations of human dignity and security: State accountability for counterterrorism intelligence cooperation. In C. Paulussen & M. Scheinin (Eds.), Human dignity and human security in times of terrorism (pp. 123–151). T.M.C. Asser Press.

Other Publications

Blogs and Op-Eds

The Cost of our Fear: Black Sites and the Erosion of our Values, 8 March 2022, Verfassungsblog

Pragmatism and Power at the ICC: US crimes not a priority, 11 October 2021, EUIdeas
(Quoted in Foreign Affairs: ‘The ICC’s Flawed Afghan Investigation: Why the Court Shouldn’t Let America Off the Hook’. Kelebogile Zvobgo, 3 November 2021)

Security vs liberty: The terms of a flawed but persistent discourse, 23 October 2020, EUIdeas 

Dans une démocratie, le pouvoir implique nécessairement un devoir corrélatif de rendre compte de son exercice’ Interview given to Journal Spécial des Sociétés, No 41, pp. 14-17, 4 July 2020 

Dealing with the (legal) risks of decision-making in times of crisis, 12 June 2020, EUIdeas 

Professional Publications 

IIJ Toolkit on Juvenile Justice in a Counterterrorism Context, International Institute for Justice and the Rule of Law (IIJ), 2017

Pre-trial detention of children in the EU – An analysis of legislation and practices in EU28, International Juvenile Justice Observatory, 2016.
Co-authored with C. Foussard and A. Vanhove.
EC-funded project JUST/2014/JACC/AG/PROC/6600: MIPREDET — Analysis of procedures and conditions of minors’ pre-trial detention

European Comparison on Juvenile Restorative Justice Practices, International Juvenile Justice Observatory, 2016. Co-authored with C. Foussard and A. Seychell.
EC-funded Project JUST/2013/JPEN/AG/4513: REVIJ — Reparation to the victim in the European Juvenile Justice Systems: Comparative analysis and transfer of best practices