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Mr. Nicholas Tsagourias

Mr. Nicholas Tsagourias
Professor of International Law
University of Sheffield

Biography Biography in PDF

Peace and Security
Cybersecurity
The Legal Status of Cyberspace
under International Law
Video | Audio
(14/07/2022, 26 minutes)

The Use of Force in Cyberspace
Video | Audio
(14/07/2022, 25 minutes)

Non-Intervention
The Principle of Non-Intervention in Cyberspace
Video | Audio
(11/06/2025, 29 minutes)

The Peaceful Settlement of Interstate Cyber Disputes
Video | Audio
(11/06/2025, 35 minutes)

Peace and Security
Cybersecurity
The Legal Status of Cyberspace under International Law
A. Jurisprudence
B. Documents

Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security, established pursuant to paragraph 4 of General Assembly resolution 66/24, 24 June 2013 (A/68/98).

Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security, established pursuant to paragraph 4 of General Assembly resolution 68/243, 22 July 2015 (A/70/174).

Report of the Open-ended Working Group on Developments in the Field of Information and Telecommunications in the Context of International Security, pursuant to Assembly resolution 73/27 and decision 75/550, 18 March 2021 (A/75/816).

Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States submitted by participating governmental experts in the Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, established pursuant to General Assembly resolution 73/266, 13 July 2021 (A/76/136).

Report of the Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, established pursuant to paragraph 3 of General Assembly resolution 73/266, 14 July 2021 (A/76/135).

C. Doctrine

J. E. Cohen, “Cyberspace as/and space”, Columbia Law Review, vol. 107, 2007, pp. 210-256.

H. Moynihan, The Application of International Law to State Cyberattacks: Sovereignty and Non-Intervention, Chatham House, London, 2019.

M. N. Schmitt (ed.), Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations, Cambridge University Press, Cambridge, 2017, pp. 11–29.

N. Tsagourias, “The legal status of cyberspace: sovereignty redux”, in N. Tsagourias and R. Buchan (eds.), Research Handbook on International Law and Cyberspace, 2nd revised and expanded edition, Elgar, Cheltenham, 2021, pp. 9-31.

H. Yeli, “A Three-Perspective Theory of Cyber Sovereignty”, Prism: Journal of the Center for Complex Operations, vol. 17, 2017, pp. 108-115.


The Use of Force in Cyberspace
A. Legal Instruments

Charter of the United Nations, San Francisco, 26 June 1945.

B. Jurisprudence

International Court of Justice, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, Judgment, I.C.J Reports 1986, p. 14.

International Criminal Tribunal for the Former Yugoslavia, Prosecutor v. Tadić, ICTY Trial Chamber, Opinion and Judgment of 7 May 1999, No. IT-94-1-T.

International Court of Justice, Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory OpinionI.C.J. Reports 2004, p. 136.

C. Documents

Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security, established pursuant to paragraph 4 of General Assembly resolution 68/243, 22 July 2015 (A/70/174).

Report of the Open-ended Working Group on Developments in the Field of Information and Telecommunications in the Context of International Security, pursuant to Assembly resolution 73/27 and decision 75/550, 18 March 2021 (A/75/816).

Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States submitted by participating governmental experts in the Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, established pursuant to General Assembly resolution 73/266, 13 July 2021 (A/76/136).

Report of the Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, established pursuant to paragraph 3 of General Assembly resolution 73/266, 14 July 2021 (A/76/135).

D. Doctrine

R. Buchan and N. Tsagourias, Regulating the Use of Force in International Law, Elgar, Cheltenham, 2021, pp. 114-131.

F. Delerue, Cyber operations and international law, Cambridge University Press, Cambridge, 2020, pp. 272-342.

J. L. Goldsmith, "Against Cyberanarchy", University of Chicago Law Review, vol. 65, 1998, pp. 1199-1250.

S. Haataja, Cyber attacks and international law on the use of force: the turn to information ethics, Routledge, London, 2019.

D. R. Johnson and D. Post, “Law and Borders – The Rise of Law in Cyberspace”, Stanford Law Review, vol. 48, 1996, p. 1367.

H. Lahmann, Unilateral remedies to cyber operations: self-defence, countermeasures, necessity, and the question of attribution, Cambridge University Press, Cambridge, 2020, pp. 47-112.

M. Roscini, Cyber Operations and the Use of Force in International Law, Oxford University Press, Oxford, 2014, pp. 43-116.

M. Roscini, “Cyber operations as a use of force”, and C. Focarelli, “Self-defence in cyberspace”, in N. Tsagourias and R. Buchan (eds.), Research Handbook on International Law and Cyberspace, 2nd revised and expanded edition, Elgar, Cheltenham, 2021, pp. 317-344.

M. N. Schmitt (ed.), Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations, Cambridge University Press, Cambridge, 2017, pp. 11–29.

N. Tsagourias and M. Farrell, “Cyber attribution: technical and legal approaches and challenges”, European Journal of International Law, vol. 31, 2020, pp. 941-967.

M. Waxman, “Cyber-Attacks and the Use of Force: back to the Future of Article 2(4)”, The Yale Journal of International Law, vol. 36, 2011, pp. 421-459.

Non-Intervention
The Principle of Non-Intervention in Cyberspace
A. Legal Instruments

Charter of the United Nations, San Francisco, 26 June 1945.

Charter of the Organization of American States, Bogotá, 30 April 1948, United Nations, Treaty Series, vol. 119, p. 48.

International Covenant on Civil and Political Rights, New York, 16 December 1966, United Nations, Treaty Seriesvol. 999, p. 171.

Constitutive Act of the African Union, Lomé, 11 July 2000, United Nations, Treaty Series, vol. 2158, p. 3.

B. Jurisprudence

International Court of Justice, Corfu Channel Case, Merits, Judgment of 9 April 1949I.C.J. Reports 1949, p. 4.
International Court of Justice, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, JudgmentI.C.J. Reports 1986, p. 14.

C. Documents

General Assembly resolution 2625 (XXV) of 24 October 1970 (Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations).

D. Doctrine

D. B. Hollis, “The Influence of War; The War for Influence”, Temple International and Comparative Law Journal, vol. 32n No. 1, pp. 31-46, 2018.


I. Kilovaty, “The international law of cyber intervention” in N. Tsagourias and R. Buchan (eds), Research Handbook on International Law and Cyberspace, 2nd ed., Edward Elgar, Cheltenham, pp. 97-112, 2021.


M. Jamnejad and M. Wood, “The Principle of Non-Intervention”, Leiden Journal of International Law, vol. 22, No. 2, pp. 345–381, 2009.


H. Lahmann, “Information operations and the question of illegitimate interference under international law”, Israel Law Review, vol. 53, No. 2, pp. 189–224, 2020.


J. D. Ohlin, Election Interference: International Law and the Future of Democracy, Cambridge University Press, Cambridge, 2020.


J. D. Ohlin and D.B. Hollis (eds), Defending Democracies: Combating Foreign Election Interference in a Digital Age, Oxford University Press, Oxford, 2021.
M. Roscini, International Law and the Principle of Non-Intervention, Oxford University Press, Oxford, 2024.


M. N. Schmitt, “’Virtual’ Disenfranchisement: Cyber Election Meddling in the Grey Zones of International Law”, Chicago Journal of International Law, vol. 19, pp. 32-67, 2018.


N. Tsagourias, “Electoral Cyber Interference, Self-Determination and the Principle of Non-Intervention in Cyberspace” in D. Broeders and B. van den Berg (eds), Governing Cyberspace: Behaviour, Power and Diplomacy, Rowman & Littlefield, Lanham, pp. 45-64, 2020, available at: https://www.thehaguecybernorms.nl/research-and-publication-posts/governing-cyberspace-behavior-power-and-diplomacy

 

Peaceful Settlement of Disputes
The Peaceful Settlement of Interstate Cyber Disputes

A. Legal Instruments

Charter of the United Nations, San Francisco, 26 June 1945.

B. Jurisprudence

Permanent Court of International Court of Justice, Mavrommatis Palestine Concessions, Judgment of 30 August 1924, P.C.I.J Series A, No. 2, p. 11.

International Court of Justice, Case of the monetary gold removed from Rome in 1943 (Preliminary Question), Judgment of 15 June 1954, I.C.J Reports 1954, p. 19.

International Court of Justice, South West Africa Cases (Ethiopia v. South Africa; Liberia v. South Africa), Preliminary Objections, Judgment of 21 December 1962, I.C.J. Reports 1962, p. 328.

C. Documents

General Assembly resolution 2625 (XXV) of 24 October 1970 (Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations).

International Telecommunication Union, Report of the Chairman of the High-Level Experts Group, Global Cybersecurity Agenda, 2008.

Report of the Group of Governmental Experts on Developments in the Field of
Information and Telecommunications in the Context of International Security
, 22 July 2015,
A/70/174.

Organization for the Security and Co-operation in Europe, OSCE Confidence-Building Measures to Reduce the Risks of Conflict Stemming from the Use of Information and Communication Technologies, Decision No. 1202, 10 March 2016, PC.DEC/1202.
European Union, EU Cybersecurity Strategy, Joint Communication to the European Parliament and the Council, 16 December 2020.
Final Substantive Report of the Open-ended working group on developments in the field of information and telecommunication in the context of international security, 10 March 2021, A/AC.290/2021/CRP.2.

Report of the Group of Governmental Experts on Developments in the Field of
Information and Telecommunications in the Context of International Security
, 14 July 2021,
A/76/135.

Organisation of American States Cybersecurity Program, 2023.

D. Doctrine

R. Buchan, D. Franchini and N. Tsagourias, The Changing Character of International Dispute Settlement: Challenges and Prospects, Cambridge University Press, Cambridge, 2023.

D. B. Hollis and E. Tikk, “Peaceful Settlement in International Law”, Texas International Law Journal, vol. 57, No. 2, pp. 1-50, 2022.

J. G. Merrills and E. de Brabandere, Merrill’s International Dispute Settlement, 7th ed, Cambridge University Press, Cambridge, 2022.

Y. Tanaka, The Peaceful Settlement of International Disputes, Cambridge University Press, Cambridge, 2018.

N. Tsagourias, R. Buchan and D. Franchini, The Peaceful Settlement of Inter-State Cyber Disputes, Oxford, Hart, 2024.

D. Additional References

United States – China Cyber Agreement, 25 September 2015.

United States – Israel Cybersecurity Partnership, 14 November 2021.

United Kingdom – China Cyber Dialogue, March 2022.

ASEAN – China Cyber Dialogue, 19 October 2022.

International Counter Ransomware Initiative, Joint Statement, 31 October-1 November 2023.
 
United States – European Union Cyber Dialogue, Joint Statement, 6-7 December 2023.