DPhil (Oxf), LLM (NYU) LLM LLB (Athens)
Antonios is Associate Professor of Public International Law at the Faculty of Law and Fellow in Law at St Anne's College. He has taught as a visitor at the Universities of Paris (Paris X – Nanterre), London (King's College), Athens (National and Kapodistrian), at the Interdisciplinary Center (IDC) in Herzliya, and at the China University of Political Science and Law in Beijing. He was previously lecturer in international law at University College London and at the University of Glasgow. Antonios has also delivered a special course at the Xiamen Academy of International Law in 2017 and has been invited by the Curatorium of The Hague Academy of International Law to serve as Director of Studies in 2021.
Antonios studied law in Athens, New York, and Oxford, during which time he also worked as a Researcher for the Hellenic Ministry of Foreign Affairs in Athens and New York and for the UN Office in Geneva, and as a Graduate Teaching Assistant for the Faculty of Law at Oxford.
Antonios is a general international lawyer and has published in a number of areas reflecting his varied research interests. His books include Disobeying the Security Council (OUP 2011, re-issued in paperback with a new introduction 2013); The Settlement of International Disputes (Hart 2012, co-edited with CJ Tams); The UN Convention on Jurisdictional Immunities of States and their Property (OUP 2013, edited by R O'Keefe and CJ Tams, ass't ed) and the Research Handbook on the Law of Treaties (Elgar 2014, co-edited with CJ Tams and A Zimmermann, and re-issued in paperback 2016). He has also published in the fields of the law of the sea, international investment law, and others.
Antonios regularly provides advice to states, international organizations, and private entities on matters of public international law. He has acted as counsel, advisor, or assistant to counsel, and has provided expert opinions in a number of cases before international and domestic courts and tribunals, including the International Court of Justice, EU courts, the European Court of Human Rights, ad hoc and ICSID arbitral tribunals, and the High Court of England and Wales. He has also provided training in international law to domestic judges, as well as diplomats, military officers, and other government officials.
Antonios is the Secretary-General of the International Law Association and the Joint Secretary of its British Branch; and member of the editorial board of Oxford Reports on International Law in Domestic Courts. He served as the Co-Rapporteur of the ILA Study Group on Principles of Engagement of Domestic Courts with International Law (2011-2016), and was contributing editor of EJIL: Talk! (the blog of the European Journal of International Law) 2014-2016.
Some of his public lectures can be found online; video-lectures for the United Nations Audiovisual Library of International Law, the Hellenic Society of International Law (in Greek), and the Université Grenoble II (in French) are available here (UN / EN), here (GR), and here (FR). You can follow Antonios on Twitter.
- Commentary to Article 46 of the Statute of the International Court of JusticeCommentary to Article 47 of the Statute of the International Court of JusticeThe relationship between the rules on state jurisdiction and sovereign immunity, as well as the rules of sovereign immunity between themselves, has been the subject of long-standing debate among international lawyers, as well as international and domestic courts. Although the starting point of any discussion is the jurisdiction of the territorial state, it is also accepted that domestic courts are barred from exercising such jurisdiction over acts of another sovereign. This latter rule has its own exceptions, namely that a foreign state is not entitled to immunity for acts performed in a commercial capacity and certain other limited circumstances. What are the consequences of such a rule-exception-exception to the exception relationship, and do they affect the waiver of immunity, the burden of proof, or the interpretation of these norms? This chapter argues that the relationship between jurisdiction and immunity as rule and exception has, in the final analysis, no particular normative weight in their application and interpretation by courts and other law-applying actors.After decades of avoiding meaningful engagement with international law, Greek courts engaged more seriously in the years of the crises. Under conditions of ‘normality’, cases ‘at the edge’ are few, and domestic courts may be unwilling in such circumstances to openly contest international law. This chapter demonstrates how Greek courts opted for avoidance when they thought that international law somehow left something to be desired when pitted against the Greek Constitution. They avoided international law by mechanistically invoking the Constitution’s normative supremacy even when they did not need to do so. This is undoubtedly resistance, but only formally principled resistance – and certainly not ‘reasonable’ resistance. But when international law is employed by both regulators and challengers as a sword and a shield on matters of high political and legal importance, resistance is no longer cheap, and can no longer be unprincipled. The stakes are too high, but so are the possibilities to influence the content and development of international law. In those circumstances, Greek courts seemed far more comfortable to forget about resisting and fall into line. Resistance here would be costly, not less so in terms of the quality of argument to be put forward. Resistance is not always futile. Sometimes, even if potentially futile, it is direly needed. Unprincipled (unreasonable) resistance is always futile, however, and definitely not useful in preparing one for proper contestation when the circumstances call for it.A short comment on issues of treaty making, authority to sign international treaties, and the legal effects of signature when treaties require also ratification, against the background of the Prespa Agreement between Greece and the former Yugoslav Republic of Macedonia with respect to the latter state's name.This essay assesses the impact of the 'Nicaraguan' cases, ie cases in which Nicaragua has been involved before the International Court of Justice, on the law of treaties. It focuses on two main aspects: the first is the relationship between various principles and (or) maxims of interpretation and the customary rules of interpretation reflected in Articles 31-32 of the Vienna Convention on the Law of Treaties. The second is the relationship between treaty and customary law, considered against the background of the quintessential Nicaraguan case, the Military and Paramilitary Activities in and against Nicaragua.ISBN: 978-3-319-62962-9This contribution discusses in some detail the forcible intervention by NATO against Serbia in 1999 in response to the situation in Kosovo. It sets out the facts and background of the crisis, along with the legal positions of the main protagonists and the reactions of the international community. It then proceeds to survey the debates surrounding the legality of the intervention and to assess the soundness of the legal justifications put forward by states and authors. Finally, it discusses the precedential value of the intervention, especially in view of claims of existence or emergence of a rule or principle of international law permitting forcible unilateral use of force in response to humanitarian crises. The contribution concludes that the NATO intervention has significant precedential value, despite the claims of even some of the states that took part in it that it should not become a precedent. But its precedential value is precisely that of confirming the unlawfulness of forcible unilateral humanitarian intervention.ISBN: 9780198784364This article examines the question of who will be subject to ICC jurisdiction with respect to the crime of aggression. One of the most contentious questions in the negotiations regarding the crime of aggression was whether the Court would have jurisdiction over nationals of a state that does not ratify the aggression amendments, but which is alleged to have committed an act of aggression on the territory of a state has accepted the aggression amendments. The question is examined here against the background of the rules in the law of treaties regarding amendments and treaty interpretation. The article considers the legal effect that the resolution of the ICC Assembly of States Parties (ASP), adopted in New York in December 2017 and activating ICC jurisdiction over aggression, will have in determining this jurisdictional question. A resolution of an international conference adopted by consensus can, in principle, be regarded as subsequent practice or a subsequent agreement of the parties to the Rome Statute that establishes the authentic interpretation of the Statute within the meaning of the Vienna Convention on the Law of Treaties. It is argued however that this particular resolution does not, in itself, provide the definitive answer as to the correct interpretation of the Rome Statute. Despite being adopted by consensus, and despite being highly relevant for the interpretation of the Rome Statute and Kampala Amendments, this resolution does not necessarily amount to a subsequent agreement or subsequent practice that the Court is legally bound to follow. Nevertheless, it is further argued that the position adopted in New York with regard to the jurisdiction of the Court over nationals of states parties that do not ratify the aggression amendments is the correct legal position and the one that the Court, including the Office of the Prosecutor, ought to adopt. The answer to the question over whom the Court will have jurisdiction with respect to aggression is to be found in Rome rather than in Kampala. We argue that the key to addressing this issue is to understand how the amendment provisions of the Rome Statute work in conjunction with basic principles of the law of treaties.ISBN: 0938-5428What is the role of domestic courts in the ideal continuum commencing from sources (where the law begins its life) and ultimately ending at the enforcement of the law in a specific case? Where, if anywhere, do they fit in this continuum? Put differently, are domestic court decisions a cause (source) or an effect (enforcement) of international law? What we argue in this essay is that enforcement of international law is reflexive, rather than reactive. Reflexitvity is defined as a circular relationship between cause and effect, and there is indeed such a circular relationship—a ‘feedback loop’—between the sources of international law and its enforcement: neither of the two can be finally identified as the ultimate cause or the ultimate effect. There is thus no real continuum, with domestic courts occupying this or that position on it. Rather, domestic court decisions are both part of the cause (sources) and of the effect (enforcement) of international law. The enforcement of a rule of law in a specific case constitutes, in accordance with the sources doctrine, yet another brick in the wall of that same ever-changing rule. And given the increasingly important position that domestic courts are assuming in the enforcement of international law, they become ever more important agents of development of that law, reinforcing their position in the doctrine of sources.ISBN: 9780198745365This is a blog post discussing the principle of consent and the Eastern Carelia precedent against the background of the Chagos Islands Advisory Opinion requested of the International Court of Justice.This is a blog post discussing the concept of the 'same case' under Article 17 of the ICJ Statute and related provisions, against the background of the Chagos Islands Advisory Opinion requested of the International Court of Justice.ISBN: 9780198716587The explosion of international investment arbitration under international investment agreements has caused significant backlash, with states parties to such agreements now seeking to reassert control over their agreements in the face of tribunals occasionally running amok. This paper considers the options for states parties to reassert control over their treaties by putting forward joint binding interpretations of relevant provisions. It posits the states parties as the masters of their treaties, reviews the relevant law and arbitral practice, and responds to common objections to joint binding interpretation.This paper discusses the potential of engaging the compulsory dispute settlement system of the 1982 UN Convention on the Law of the Sea in order to resolve disputes over the South China Sea. It does so both in general, but also specifically against the background of the Jurisdiction and Admissibility Award of an Annex VII Arbitral Tribunal in the arbitration initiated by the Philippines against the People's Republic of China. The paper discusses in particular the trend in seeking to shoehorn disputes into existing compromissory clauses in order to establish the jurisdiction of a court of tribunal, as well particular issues of jurisdiction and admissibility that may (and do) arise in South China Sea disputes being brought under Part XV of the UN Convention.ISBN: 1816-983XThis is a short piece which discusses the implications of the ICC exercising jurisdiction over the crime of aggression for the responsibility of states.ISBN: 0017-8063This contribution discusses the judgment of the International Court of Justice in the North Sea Continental Shelf cases between Denmark and the Netherlands on the one hand, and Germany on the other. After setting out the background to the dispute and the judgment of the Court, it focuses on the Court's discussion of the sources of international law and their relationship, as well as on the definition and the rules for the delimitation of the continental shelf. It concludes that the cases are indeed a landmark as to the former set of issues, but much less so as to the latter. It was rather the high watermark of geomorphological approaches to the continental shelf and of equitable principles for its delimitation, but the law has now moved on despite habitual incantations of the catchy expressions used by the Court with respect to the continental shelf.ISBN: 9781849467889ISBN: 9780198716587This contribution to the Research Handbook on the Theory and Practice of International Law-Making discusses the law-making potential of domestic courts. Given the seemingly strict 'dualist' approach of international law to domestic law and domestic court decisions ('merely facts'), the paper demonstrates the modest international law-developing function of domestic courts: it first details their methods in engaging international law, and then discusses the impact of such engagement. It concludes that domestic courts may, in terms of content, fine-tune rules of international law rather than set grand principles. In terms of process, this is done by 'suggesting' the fine-tuning, rather than in any way single-handedly developing international law.This chapter discusses whether judicial dialogue on international law between domestic courts may be conceptualised as a new means of interpretation--beyond the Vienna Convention on the Law of Treaties. After defining 'dialogue' and presenting its various potential iterations, the chapter argues that in fact judicial dialogue between domestic courts is required under international law, including the Vienna Convention. This is because domestic court decisions on international law may constitute subsequent practice which is to be taken into consideration when interpreting a treaty, in accordance with Article 31(3)(b) VCLT. But domestic court decisions may also constitute practice and/or reflect opinio juris, which domestic courts must find in order to determine the existence and content of customary international law. As such, domestic courts must engage with the relevant decisions on international law by domestic courts in other jurisdictions. They must engage in judicial dialogue as a means for interpreting international law.DOI: 10.1163/22119000-01702007ISBN: 1660-7112This contribution does not aim to quantify the influence of English courts on the development of international law, but rather to highlight their contribution in that development by focusing on important decisions on the law of immunity and on UN Law and the law of international organisations, and by referring to further notable decisions in other areas of international law. This is done against the background of an understanding of domestic courts as 'agents' of international law development through instigation, reaction, and approval, which is also explained in the paper.This paper reviews the contribution of the International Court of Justice in defining the concept of aggression against the background of the Kampala Amendments to the 1998 Rome Statute of the International Criminal Court. It argues that the ICJ, while not contributing directly to the elaboration of the concept of aggression, has indeed influenced the internal gradation of the concept of aggression through drawing an implicit parallel with the concept of armed attack. The paper then completes this picture by introducing a three-step parallel gradation of concepts: use of force-armed attack-serious breach of jus cogens and use of force-act of aggression-war and/or crime of aggression; and by discussing their potential relationship and interaction.ISBN: 9781107015265A response to Devika Hovell's AJIL article on 'Due Process in the United Nations'.A brief discussion of the legality of the potential instruction to Royal Navy submarines to use nuclear weapons contained in the so-called 'Letter of Last Resort', against the background of the Labour Party Leader's statement that he would not use nuclear weapons under any circumstances.L'objectif de cette contribution est d'examiner brièvement la réaction des États face aux sanctions illégales. Deux questions se posent à ce sujet : primo, les sanctions internationales, unilatérales ou collectives, émanant des Nations Unies, peuvent-elles être illégales? secundo, quels sont les recours des États ciblés par des sanctions illégales, et celui des États tiers tenus dappliquer ces sanctions?ISBN: 978-2-343-05590-9ISBN: 9782802747710DOI: 10.1007/978-94-6265-051-0_8This chapter deals with the responsibility of the EU under international law for unilateral sanctions. Like States, international organizations may also adopt unilateral sanctions against States or other international organizations. The EU has been particularly active in this respect. After some terminological clarifications regarding sanctions and countermeasures, the chapter examines EU practice in imposing unilateral sanctions on third States and sets out the conditions for legal resort to such sanctions. The chapter then proceeds to discuss the potential engagement of the international responsibility of the EU for the imposition of sanctions. If such measures are attributable to the EU, and they are in breach of the EUs international obligations, then they must be justified as countermeasures. Otherwise the EUs international responsibility will be engaged. The chapter then examines the mechanisms for implementing that international responsibility on the part of the States that have been unlawfully targeted by EU sanctions.ISBN: 978-94-6265-051-0DOI: 10.1163/15723747-01202008International organisations often lack operational capacity, but may command significant normative power over states. By contrast, states have organs with significant operational capacity. Adoption of sanctions by the UN Security Council under Chapter VII of the UN Charter would remain a dead letter without enlisting the capacity of states to implement these measures on the ground. The UN and its member states thus both contribute to a single harmful outcome. International responsibility for this is shared in practice, as demonstrated by recent developments in domestic and regional international courts: states are held responsible by domestic or regional international courts, and are forced to disobey the Security Council in order to comply with their human rights obligations. In turn, the states put pressure on the Security Council to reform the offending regime, forcing the UN to comply with its own international obligations.ISBN: 1572-3739Brief discussion of the alleged 'fundamental right' of states to be free from economic coercion against the background of the Greek sovereign debt crisis 2010-2015 published just ahead of the second Greek parliamentary elections of 2015.The relationship between the concept of the 'crime of aggression' and of 'act of aggression' under the ICC Statute and under general international law respectively remains unclear. This post discusses the concept(s) of aggression against the background of the jurisprudence of the ICJ.DOI: 10.7574/cjicl.04.03.616This paper seeks to determine if there is a fundamental right of States to be free from economic coercion, against the background of international law permitting economic coercion as a means for its own implementation. After defining coercion and other cognate terms, it surveys the limits to (economic) countermeasures and (economic) sanctions, and determines that any 'sphere of economic freedom' of States is essentially a relative concept, without an irreducible core. Public International Law does not currently establish a fundamental right to be free from economic coercion--though one should probably be established.ISBN: 2050-1706A brief comment on Karen Alter's 'New Terrain of International Law'.This brief paper, based on a conference presentation, discusses the legal limits to the powers of the Security Council to intervene in 'domestic conflicts'. Most importantly, it focus on the control of these limits by the UN member States. It concludes the UN members may control the decisions of the Council to intervene in domestic conflicts it considers to constitute 'threats to the peace' in a decentralised manner.ISBN: 978-2-233-00706-3DOI: 10.1163/22119000-01504007This article discusses the potential provisions on national treatment and MFN to be included in a future EU Model BIT against the background of the leaked draft text of the Canada-EU Comprehensive Economic and Trade Agreement (CETA) investment chapter. It concludes that the EU treaty practice seems to be closer to investment protection models influenced by NAFTA, such as those prevalent in the Canada and US Model BITs, and that a future EU Model BIT along these lines will depart significantly from the investment treaty practice of EU Member States.ISBN: 1660-7112DOI: 10.4337/9780857934789.00020This paper explores the presumptive tension between the pacta sunt servanda rule (the rule that commitments ought to be honoured) and the possibility for unilateral or consensual suspension or termination of treaties. It argues that the pacta sunt servanda rule seems able to accommodate the various methods of suspension or termination: under the general international law of treaties, termination or suspension is not actually unilateral; only the invocation of relevant grounds is. Further, both grounds for suspension or termination, as well as defences under the law of responsibility (which achieve results similar to suspension) are narrow and thus hard to invoke successfully. Finally, the law allows states to devise their own exit clauses in treaties. This leads to very broad exit clauses allowing for unilateral termination or withdrawal. This however being part of the pactum, it does not formally put pressure on the pacta sunt servanda rule.ISBN: 978 0 85793 477 2ISBN: 978-2-233-00711-7Report of the Working Session of the ILA Study Group on Principles of Engagement of Domestic Courts with International Law, detailing the progress in the work of the Study Group since the publication of the Preliminary Report.ISBN: 0074-6738DOI: 10.4337/9780857934789The Research Handbook on the Law of Treaties is a collection of essays on fundamental issues in international treaty law. The Research Handbook´s main objective is to identify key challenges facing the modern law of treaties and to assess future directions that the law will take. The main themes of the Handbook revolve around the spatial, personal and temporal dimensions of treaties, the tensions that arise due to the need for flexibility in treaty relations, the interaction between treaty regimes and the potential ruptures, as well as the expansion of treaty law to international organisations, corporations and individuals. Each chapter includes an 'agenda for research', highlighting areas where future work may prove fruitful.ISBN: 9780857934772DOI: 10.1093/jcsl/kru017The UN Security Council wields immense power under Article 41 of the Charter, a power that it has not shied away from employing regularly over the past two and a half decades. As the use of the sanctioning power of the Security Council increased, so did the calls for holding the exercise of that power to account. This article argues that legal accountability, that is, international responsibility is the form of accountability best suited for controlling the sanctioning power of the Security Coun-cil. It demonstrates how the UN can be held responsible by the UN Membership for Security Council excesses in the exercise of its powers, and argues that the ancillary obligation of transparency operationalises decentralised control of the Council by the UN Member States. It concludes that decentralised legal accountability, though risky, is effective and has even induced the Security Council to establish or improve internal mechanisms enhancing accountability for sanctions.ISBN: 1467-7954The Kadi judgments of the courts of the EU have received enormous scholarly attention and have had significant practical impact. And reasonably so: they are landmark decisions, with numerous implications for several crucial issues, from the relationship between different legal orders to the primacy of Security Council decisions, from the required level of protection of fundamental human rights in the application of coercive measures against individuals to the competence of the EU, and so forth. This brief study focuses on one particular aspect of the Kadi decisions: their employment of the Solange argument as a justification for disobeying the Security Council by not implementing its binding decisions.ISBN: 978-0-415-64031-2A short comment on the international law aspects of the UK Conservative Party paper that proposes scrapping the Human Rights Act 1998.The paper assesses the legal regime governing recourse to force from the perspective of 'contemporary positivism'. It provides a basic introduction to positivist international law and its critique and charts how positivism, faced with decades of anti-positivist critique, has adjusted itself. More specifically, it analyses how in response to criticism, positivism has embraced a more 'liberal' approach to the identification of sources. Applying these findings to the specific problem of military force, the paper outlines the main challenges facing a positivist understanding of the jus ad bellum. These are (i) the loss of predictability of the legal rules (''anything goes"), which is a consequence of the liberalisation of sources; and (ii) the attraction, even among positivist scholars, to invoke "quasi-legal" arguments based on legitimacy, morals or political necessity.ISBN: 9781107019263DOI: 10.1017/CBO9781139108843.021This paper discusses transparency in the working method of the United Nations Security Council. It describes the institutional design of the organ and the evolution of Security Council powers, and seeks to identify whether there is an obligation for the Council to act in a transparent manner in the exercise of its powers. The paper argues that transparency is an 'ancillary' obligation incumbent on the Council, to allow for decentralised control over the exercise of its powers by Member States of the UN. Transparency having no independent normative charge, we do not how much of it is good -- this is determined by a pattern of protest and reaction between the Security Council and the Member States called upon to implement its decisions.ISBN: 978-1107021389Buchbesprechung der 3. Auflage des UN-Charta Kommentars von Simma et al.ISBN: 0042-384XDOI: 10.1017/S0922156513000228The introductory paper to a symposium issue of the Leiden Journal of International Law, edited by the authors, dealing with the function of domestic courts as agents for the development of international law. The paper 'sets the scene' for the contributions to the symposium, which seek to trace the impact of domestic courts in the development of canonical areas of international law, such as jurisdiction, immunity, state responsibility, the law of international organisations/human rights, and the law of armed conflict/conduct of hostilities. It discusses the formal quality and actual influence of domestic court decisions on the development of international law, and introduces the concept of 'agents' of international law development. This is the analytical perspective that the contributions to the symposium adopt.ISBN: 0922-1565A Report prepared for the KROC Institute's Sanctions and Security Research Program, assessing reforms to the 1267/1989 sanctions regime of the Security Council against the standards required by European Courts, including the Court of Justice of the European Union and the European Court of Human Rights.Comment on the ECJ's decision in Kadi II.This paper discusses (in French) whether countermeasures can be invoked as a justification for disobeying binding decisions of the Security Council under Chapter VII of the UN Charter. The first part establishes how the Security Council may engage the international responsibility of the UN and who should be allowed to determine that such engagement has in fact taken place. The second part argues that disobedience of illegal sanctions adopted by the Council may be justified under international law as a countermeasure in response to the Council's (the UN's) internationally wrongful act.ISBN: 0035-0788This blog entry is based on a talk delivered at the University of Amsterdam in the framework of the SHARES (shared responsibility) project. It discusses how responsibility is shared between the UN and member-States for the adoption and implementation of UN sanctions under Chapter VII of the Charter.