Dr Matthew Gillett

Senior Lecturer
Essex Law School
Dr Matthew Gillett



Dr. Matthew Gillett is an academic and generalist international lawyer with extensive experience before the international courts. In 2022, he was appointed as a United Nations Special Mandate Holder (the Expert from the Western Europe and Others Group in the Human Rights Council's Working Group on Arbitrary Detention). He is currently the Chair-Rapporteur of the Working Group. For almost 15 years, he worked in international organisations in The Hague (particularly the International Criminal Court ("ICC") and the International Criminal Tribunal for the former Yugoslavia ("ICTY")), primarily as a Prosecution Trial Attorney and Appeals Counsel. He has also conducted investigations in various conflict zones, including as a Human Rights Officer with the United Nations Assistance Mission in Afghanistan ("UNAMA"). Matthew has published widely on matters relating to international law, peace and security and the environment. His works appear in publications such as the Journal of International Criminal Justice, the Washington University Global Studies Law Review, the International Criminal Law Review, the Criminal Law Forum, the Australian International Law Journal, the Journal of Law and Medicine, and the Yale Journal of International Affairs. His monograph titled "Prosecuting Environmental Harm before the International Criminal Court" was published by Cambridge University Press in June 2022. He has won multiple awards for his academic work, including the Inaugural Benjamin B. Ferencz Essay Competition and the Sherman Emerging Scholar prize. His publications have been cited before international and hybrid courts, including in filings and Decisions of the Colombia Special Jurisdiction for Peace ("Pre-Report on Charging Environmental Damage before the Jurisdicción Especial para la Paz"); the International Criminal Court (e.g. "Collective dislocation; crimes of displacement, property depravation and discrimination under international criminal law", Routledge; "The Call of Justice: Obligations under the Genocide Convention to Cooperate with the International Criminal Court”, CLF) and the Special Tribunal for Lebanon (e.g. "Fast-Track Justice", JICJ; "The Special Tribunal for Lebanon Swiftly Adopts Its Rules of Procedure and Evidence", JICJ); see also International Court of Justice Bibliography no. 62 ("Prosecuting Environmental Harm before the International Criminal Court"). Matthew has led and participated in a range of projects, including inter-disciplinary work on hate speech (which resulted in the Hartford Guidelines on Speech Crimes), assisting the International Crimes Division of Uganda, assisting the Special Jurisdiction for Peace in Colombia, and training prosecutors in Kenya. His work encompasses: International Criminal Law; Human Rights; Terrorism and Counter-Terrorism; Procedure and Evidence; Open-Source investigations; the Environment; International Humanitarian Law; Mediation (as a qualified mediator); Speech Crimes; and Aggression. From February 2022 to February 2024, Matthew is the Principal Investigator on an AHRC research grant funded project titled: Legal, Human Rights, Cultural and Environmental aspects of founding a Biocultural Indigenous University in the Andean Amazon of Colombia. In December 2022, he served as a Ph.D. jury member for Sciences Po, Institut d’études politiques, France.


  • PhD Leiden University,

  • LL.M University of Michigan–Ann Arbor,

  • LL.B University of Otago,

  • B.A. (political science) University of Otago,


University of Essex

  • Senior Lecturer, Law School, University of Essex (27/9/2021 - present)

Other academic

  • Senior Professional Practice Fellow, Law School, University of Otago (31/12/2022 - 10/2/2023)

Research and professional activities

Research interests

Environmental Law

Open to supervise

International Criminal Law

Open to supervise

Terrorism and Counter-Terrorism

Open to supervise

Conferences and presentations

Denial of Statehood as a Indictor of Genocidal Intent

Invited presentation, 'Legal and Social Consequences of Crimes of International Law in Ukraine', 14/12/2023

Enforcing ecocide: how to prosecute environmental harm under international criminal law


Environmental Harm under the Draft Crimes Against Humanity Convention

Invited presentation, International Law Association ILW2023, International Law Weekend, 20/10/2023

Ecocide in the Anthropocentric Era

Invited presentation, University of Otago Bioethics Centre, 2/10/2023


Keynote presentation, International Law Presentation, Cambridge, United Kingdom, 13/7/2023

Reconciling Human Rights Fact Finding and Adjudication

Invited presentation, University of Essex Human Rights Centre 40th Anniversary, 8/7/2023

Prosecuting crimes in Ukraine before the International Criminal Court

Invited presentation, Bringing Justice for Ukraine, Crime of Aggression, War Crimes, Crimes against Humanity, Genocide, Poland, 19/5/2023

Ecocide: Prospects and Pitfalls

Invited presentation, Conference of the Bureau of International Crimes, Conference of the Bureau of International Crimes, Netherlands, 21/4/2023

Ecocide: Past, Present and Future

Keynote presentation, Asser Institute: Environmental Protection under International Law, Environmental Protection under International Law, The Hague, 14/12/2022


Invited presentation, Mnemonic Conference on Documenting International Crimes and Human Rights Violations, 2/12/2022

Child witnesses and victims of war

Keynote presentation, Barnahus workshop, 12/10/2022

Fact-finding and evidence of environmental harm in international criminal justice

Invited presentation, Enhancing Environmental Protection in Armed Conflicts, Ferrara, Italy, 19/9/2022

Workshop on Environmental Law and International Justice

Invited presentation, American University of Paris, 9/6/2022

Session 1: The situation in Ukraine

Invited presentation, War Crimes Committee Conference, 9/5/2022

Investigating Human Rights and Arbitrary Detention

Keynote presentation, United Nations Assistance Mission in Somalia (UNSOM) Workshop on Serious Crimes, Human Rights and Arbitrary Detention, 24/11/2021

Gender and Early Warning of Genocide

Invited presentation, Adjudicating Gender-Based Persecution at the ICC and Beyond - Northumbria, Adjudicating Gender-Based Persecution at the ICC & Beyond: A Monumental Step and the Challenges that Lie Ahead Conference, Newcastle upon Tyne, United Kingdom, 7/10/2021

Environmental crimes and ICC jurisdiction

Invited presentation, IBA War Crimes Committee, 17/5/2021

Challenges to Prosecuting Paramilitaries: Insights from the former Yugoslavia and Syria

Invited presentation, Asser Institute Webinar, 3/6/2020

The Legacy of the International Criminal Tribunal for the former Yugoslavia with respect to the Crime of Genocide

Invited presentation, IX Ibero-American Week of International Justice, 3/6/2019

Report on Crime of Starvation

Invited presentation, IBA Conference 2019, 13/4/2019

Proof and Privacy in the Digital Age: The Use of Digitally-Derived Evidence at the International Criminal Court

Invited presentation, 8th Annual Cambridge International Law Conference, 20/3/2019

Proving the intentional destruction of cultural heritage in armed conflict and situations of forcible displacement

Invited presentation, Protecting Cultural Heritage in Armed Conflict and Situations of Forcible Displacement: An (Emerging) Human Right?, 2/3/2019

The Role of the ICCBA in Supporting and Enhancing Positive Complementarity

Invited presentation, ICC Assembly of State Parties, 11/12/2018

Criminal Prosecutions and Accountability

Invited presentation, Human Rights, Transitional Justice, and Environmental Protection, 18/7/2018

Prosecuting Environmental Harm from Military Attacks, Illegal Exploitation of Species, and Toxic Dumping

Invited presentation, The International Criminal Responsibility of War’s Funders and Profiteers, 24/6/2017

Forcible displacement: law and evidence

Invited presentation, American Society of International Law Annual Conference, 10/4/2015

Atrocity and Accountability: the Impact of International Criminal Tribunals on Peacemaking and Reconciliation

Keynote presentation, Sherman Award Keynote Speech, 3/10/2013

Accountability for Aggression Under International Criminal Law

Invited presentation, 21ST ANNUAL ANZSIL CONFERENCE, 5/7/2013

Prosecuting environmental damage under international criminal law

Invited presentation, 4th Biennial Conference of the European Society of International Law, 3/9/2010

Teaching and supervision

Current teaching responsibilities

  • Foundations of Human Rights (HU100)

  • Human Rights, Regional Systems & Global Challenges (HU200)

  • Current Challenges in the Law of Armed Conflict (LW804)

  • International Criminal Law 2: Advocacy and Litigation (LW809)

  • International Human Rights Law: Law and Practice (LW901)

  • Final Year Research Project (LW304)


Journal articles (16)

Gillett, M. and Fan, W., (2024). Expert Evidence and Digital Open-Source Information: Bringing Online Evidence to the Courtroom (Dec 2023). Journal of International Criminal Justice. 21 (4), 661-693

Gillett, M., (2024). Reconciling the Dual-Faceted Mandates of Quasi-Judicial Human Rights Bodies: the Working Group on Arbitrary Detention’s Prima Facie Approach to Evidence. Human Rights Law Review. 24 (1), ngad045-

Gillett, M., (2023). Criminalizing Reprisals Against the Natural Environment. International Review of the Red Cross. 105 (924), 1463-1496

Gillett, M., (2023). Fact-Finding Without Rules: Habermas’s communicative rationality as a framework for judicial assessments of digital open-source information. Michigan Journal of International Law. 44 (3), 301-348

D’Alessandra, F. and Gillett, M., (2019). The War Crime of Starvation in Non-International Armed Conflict. Journal of International Criminal Justice. 17 (4), 815-847

Gillett, M. and Lostal, M., (2017). “Reflexiones Sobre el Caso Prlić et al.”. En Letra: Derecho Penal. 3 (5)

Gillett, M., (2017). Testing the Limits of the Law Against Those Who Test the Tribunal’s Limits. Journal of International Criminal Justice. 15 (4), 775-797

Gillett, M. and Ventura, M., (2014). “The Fog of War: Prosecuting Illegal Uses of Force as Crimes Against Humanity” (Winner of Inaugural Benjamin B. Ferencz Writing Prize 2012). Washington University Global Studies Law Review

Gillett, M., (2013). The Anatomy of an International Crime: Aggression at the International Criminal Court. International Criminal Law Review. 13 (4), 829-864

Gillett, M., (2012). The Call of Justice: Obligations Under the Genocide Convention to Cooperate with the International Criminal Court. Criminal Law Forum. 23 (1-3), 63-96

Gillett, M. and Schuster, M., (2011). Fast-track Justice: The Special Tribunal for Lebanon Defines Terrorism. Journal of International Criminal Justice. 9 (5), 989-1020

Gillett, M., (2010). “Victim Participation at the International Criminal Court”. Australian International Law Journal

Gillett, M. and Schuster, M., (2009). The Special Tribunal for Lebanon Swiftly Adopts Its Rules of Procedure and Evidence. Journal of International Criminal Justice. 7 (5), 885-909

Gillett, M., (2008). “Assisted Arrest: Ending Impunity at the ICC”. Yale Journal of International Affairs

Gillett, M. and Gillett, G., (2008). “Intent, the Ethos of a Caring Society and Justice”. Journal of Law and Medicine. 16 (2), 209-215

Gillett, M., (2003). “Analysing America’s War on Terrorism: Preemptive Self-Defence in International Law”. New Zealand Students’ Law Journal

Books (2)

Gillett, M., Grunfeld, K. and Ramuš Cvetkovič, I., Lex Ad Astra: Non-State Actor Accountability for Space Pollution. Brill

Gillett, M., (2022). Prosecuting Environmental Harm before the International Criminal Court. Cambridge University Press. 9781009070027

Book chapters (9)

Gillett, M., “Article 7(1)(b): Extermination”. In: Commentary on the Law of the International Criminal Court, (“Klamberg Commentary”). Case Matrix Network

Gillett, M., (2022). Animals in Protected Zones (part of Winner of European Society of International Law 2023 Collaborative Book Prize). In: Animals in the International Law of Armed Conflict. Editors: Peters, A., de Hemptinne, J. and Kolb, R., . Cambridge University Press. 9781316512043

(2018). Armed Conflict and Forcible Displacement. In: Armed Conflict and Forcible Displacement: Individual Rights under International Law. Editors: Proukaki, EK., . Routledge. 221- 244

Gillett, M., (2017). “Chapter 10: Eco-struggles: using international criminal law to protect the environment during and after non-international armed conflict”. In: Environmental Protection and Transitions from Conflict to Peace Clarifying Norms, Principles, and Practices. Oxford University Press. 0191087580. 9780191087585

Gillett, M., (2017). “Chapter 8: Collective Dislocation: Crimes of Displacement, Property-Deprivation and Discrimination under International Criminal Law”. In: International Law and the Rights of those Displaced by Armed Conflict

Gillett, M., (2017). Eco-Struggles. In: Environmental Protection and Transitions from Conflict to Peace. Oxford University PressOxford. 220- 254. 0198784635

Gillett, M., (2013). “Chapter 6: Environmental damage and international criminal law”. In: Securing the Rights of Future Generations: Sustainable Development and the International Criminal Law Regime in Practice

Gillett, M., (2013). Environmental Damage and International Criminal Law. In: Sustainable Development, International Criminal Justice, and Treaty Implementation. Cambridge University Press. 73- 99. 9781107032934

Gillett, M., (2012). “Prosecuting Environmental Damage under International Criminal Law”. In: Selected Proceedings of 2010 European Society of International Law Conference in Cambridge. 329- 338

Conferences (1)

Gillett, M., Ecocide: the prospects and pitfalls of prosecuting environmental harm under international criminal law

Reports and Papers (7)

Gillett, M., International Criminal Tribunal for the former Yugoslavia: Manual on Developed Practices

Gillett, M., Environmental Harm as a Crime under the Rome Statute

Gillett, M., Situation in Ukraine: Hate Speech as the Crime Against Humanity of Persecution

Gillett, M. and Garahan, S., (2023). Written Evidence by Dr Sabina Garahan and Dr Matthew Gillett (IMB0015) on UK Illegal Migration Bill

Gillett, M., González Morales, F., Ashwini, KP., Obokata, T., Edwards, AJ. and Mullally, S., (2023). Joint Letter by United Nations Special Procedures concerning UK Illegal Migration Bill

Gillett, M., (2018). The Peace and Justice Initiative: submission on Speech Crimes for the Crimes Against Humanity Convention

Gillett, M. and Wilson, R., (2017). The Hartford Guidelines on Speech Crimes in International Criminal Law

Other (7)

Gillett, M., « Le travail du Bureau du Procureur devant les Tribunaux pénaux internationaux »,Institut International de Recherche sur la Conflictualité

Gillett, M., (2023).A Tale of Two Definitions: Fortifying Four Key Elements of the Proposed Crime of Ecocide - Opinio Juris,Opinio Juris

Gillett, M., (2023).The Kakhovka Dam and Ecocide,Verfassungsblog of International Law

Gillett, M., (2022).Redress for environmental destruction: is it time for an International Court for the Environment (ICE)?,FIFTEEN EIGHTY FOUR Academic perspectives from Cambridge University Press

Gillett, M., (2014).Has the Pre-Trial Chamber jeopardized the Gbagbo trial at the International Criminal Court?,Beyond the Hague

Gillett, M., (2007).“Intrepid Justice: Prosecutorial Discretion at the International Criminal Court”. New Zealand International Review

Gillett, M., (2007).““International Law Issues in the South Pacific” edited by Geoff Leane and Barbara von Tigerstrom (Ashgate Publishing Limited, 2005)”, (Book Review). New Zealand International Review

Grants and funding


Crimes against cultural heritage in the Colombian conflict context

Instituto Colombo-Alem�n para la Paz (CAPAZ)


Speech crimes in international criminal law - updating the Hartford guidelines

Peace and Justice Initiatve

Human Rights Fact-finding: determining the misuse of arbitrary detention against migrants and environmental defenders

University of Essex (QR Impact Fund)


Legal, Human Rights, Cultural and Environmental aspects of founding a Biocultural Indigenous University in the Andean Amazon of Colombia

Arts and Humanities Research Council

+44 (0) 1206 872312


5NW.8.11, Colchester Campus

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