Overview

DPhil (Oxford), LLM (NYU), LLM LLB (Athens) 
Barrister | Public International Law 

Antonios Tzanakopoulos is Professor of Public International Law at the University of Oxford and Fellow in Law at St Anne’s College. He is also admitted to practice in Athens, Greece. He brings a wealth of academic and practical expertise to Three Stone Chambers, where he advises states, international organisations, and other actors on complex matters of public international law. 

Antonios has acted as counsel and advocate in numerous high-profile cases before international and domestic courts and tribunals, including the International Court of Justice (ICJ); The International Tribunal for the Law of the Sea (ITLOS); The European Court of Human Rights; EU courts; ICSID and ad hoc arbitral tribunals; and the Courts of England and Wales. 

Some of his recent cases include: 

  • Counsel for the Republic of Cyprus in the Chagos Advisory Opinion before the ICJ. 
  • Counsel and advocate for the Republic of Cyprus in its Article 63 intervention in Ukraine v Russia (Allegations of Genocide) before the ICJ.  
  • Counsel for Malaysia in the two Advisory Opinions (of 2024 and 2025) on the Occupied Palestinian Territory before the ICJ . 
  • Counsel and advocate for Germany in Nicaragua v Germany before the ICJ.  
  • Counsel for Equatorial Guinea in The M/T ‘Heroic Idun’ (No 2) before a Special Chamber of ITLOS.  
  • Counsel for Sudan in ICSID Case No ARB/14/2.  
  • Counsel for the respondent child in London Borough of Brent v AG and Others [2021] EWHC 1253 (Fam) 

Antonios has taught at leading institutions worldwide, including Paris II–Assas, Paris X–Nanterre, Angers, King’s College London, Athens, Bern (World Trade Institute), Jerusalem (Hebrew University), and Beijing (CUPL). He previously held academic posts at University College London and the University of Glasgow. He has delivered special courses at the Xiamen Academy of International Law and at The Hague Academy of International Law. Antonios also provides training in international law to judges, diplomats, military officers, and government officials, including through United Nations programmes. 

His legal education spans Athens, New York, and Oxford, and his research interests are broad and interdisciplinary. Antonios is the author and editor of several influential works, including: 

  • Disobeying the Security Council (OUP, 2011; reissued 2013) 
  • The Settlement of International Disputes (Hart, 2012; 2nd ed. 2022, co-edited) 
  • The UN Convention on Jurisdictional Immunities of States and their Property (OUP, 2013, co-edited) 
  • Research Handbook on the Law of Treaties (Elgar, 2014; reissued 2016, co-edited) 
  • The Engagement of Domestic Courts with International Law (OUP, 2024, co-edited) 

He has published extensively on state responsibility, the law of the sea, international investment law, and treaty law. He serves as Secretary-General of the International Law Association and Joint Secretary of its British Branch.

Antonios is fluent in German and Greek, and has a working knowledge of French.