Fifth Antonio Cassese Lecture: The Role of International Lawyers between Theory and Practice

The Antonio Cassese Initiative is pleased to publish the speech given by Judge Abdulqawi Ahmed Yusuf on the occasion of the opening of the Cassese Archive. The speech has been kindly freed up by Oxford University Press (photo by EUI).

1. Introduction

It gives me great pleasure to be here with you today to deliver the fifth ‘Antonio Cassese Lecture’, and I thank the organizers for their kind invitation.

I am also delighted to be associated with the opening of the Antonio Cassese Archive here at the European University Institute (EUI), a resource that I am sure will be of great interest to scholars of today and of the future. This occasion also marks five years since the passing of Nino, giving us an opportune moment to celebrate his accomplishments.

In my lecture today, I will outline my thoughts on the role of the international lawyer between theory and practice. In doing so, I will make reference to Nino’s academic and professional work, which I believe are particularly instructive in this context. As you know, in addition to his outstanding academic career, Nino was an accomplished practitioner. He served as President of the European Committee for the Prevention of Torture and was President of both the International Criminal Tribunal for the former Yugoslavia and the Special Tribunal for Lebanon. He was also the Chairperson for the International Commission of Inquiry on Darfur, amongst his many other roles in international law.

Nino’s industriousness in all spheres of his life was tireless. But his dedication to the practice of international law was not due to mere restlessness. Rather, it was a manifestation not only of how Nino saw the world, but also of the role of international law and international lawyers within that world. In the words of one of his close friends:

For him, anyone doing academic teaching and research must obviously seek and reveal the truth in its deepest, most hidden core, beyond external appearances, rhetorical show, platitudes, and political or ideological shields. But this critical research cannot and must not be an end in itself. Understanding is not enough: knowledge must be continued and completed in action, it must be the instrument used to improve the world, the fate of man and society.1

‘Understanding is not enough: knowledge must be continued and completed in action.’ Today, I am going to explore this relationship between knowledge and action. How are theoretical enquiries about international law related to its practice? How do they influence each other? Is international law different from other academic disciplines in this respect? And what can we learn in this context from Nino about the balance between theory and practice?

2. The Elucidation of Rules in a Decentralized System

I start with what we might call the elucidation of rules in a decentralized system. It seems to me that the relationship between theory and practice in public international law is stronger than in many other disciplines. This is mainly due to the systemic nature of the international legal system and the fact that the law is practised by many accomplished academics, whether as judges, government advisers, or counsel. In my experience, there are various ways in which theory — or perhaps I should say, more broadly, the academic study of international law — influences the practice of the discipline; but let me share with you an important example.

The example I will use stems from the decentralized nature of international law. At the international level, we are not blessed (or perhaps not cursed) with a legislature that enacts statutes and laws. It is as a result of this decentralized character of international law that the Advisory Committee of Jurists — the body charged with drafting the Statute of the Permanent Court of International Justice (PCIJ) — recognized the role of judicial decisions and the ‘teachings of the most highly qualified publicists’ in the determination of legal rules. Following this recognition, a suggestion from the Advisory Committee made its way into the Statute of the PCIJ which now appears as Article 38(1)(d) of the Statute of the International Court of Justice (ICJ).

The rationale for this ‘formal’ acknowledgement of the role of academics in the determination of legal rules is quite simple — there is no general ‘co-ordinating body’ in the international sphere tasked with giving voice to unwritten rules. Rules of customary international law and general principles of law exist instead, one might say, in the ether. The rules only take shape when someone identifies pertinent practice and opinion juris or relevant domestic laws. This does not happen by itself. Instead, it requires someone to study, analyse and rationalize that evidence, and to elucidate the resulting rule of law.

There are various bodies that fulfil such a function on the international plane: sometimes a court, like the ICJ, plays such a role, as does the International Law Commission (ILC) in relation to the projects that it undertakes. But despite the codification of many laws, the international sphere continues to be characterized by diffuse state practice and unwritten rules. It is in relation to this that scholars play an important role. They tackle the question of latent rules of custom before the issue can find its way to courts or the ILC. Scholars have the time and — at least, one hopes, here at the EUI — the resources to be able to systematically and thoroughly analyse the evidence that is before them. Many of the great works of international legal scholarship of the 20th century are studies of this kind, and they continue to have a profound and enduring impact on the codification and progressive development of the law.

One example is the work of the International Committee of the Red Cross (ICRC) on customary international humanitarian law (IHL). The researchers who worked on the ICRC project examined state practice related to IHL and identified 161 rules that exist as customary international law. In this context, of course, the Geneva and Hague regimes play an important role in the regulation of armed conflict, but the on-going work on customary rules of IHL is important for two main reasons. The first is that the Conventions only bind States Parties. The Geneva Conventions have been ratified almost universally but the same cannot be said for the first Additional Protocol or the Hague Conventions. The work of the ICRC therefore confirms the continued existence of parallel rules of custom that bind all states.

The second reason the ongoing work on customary rules is important concerns the rules of customary international law in relation to non-international armed conflicts. These are more detailed than those contained in conventional law. Parties to a non-international armed conflict are bound by common Article 3 of the Geneva Conventions, but the article does not provide detailed guidance regarding the conduct that is impermissible in such conflicts. Additional Protocol II elaborates on common Article 3, but remains lacking in detail and has not been ratified by some states in which armed conflicts are taking place,2 particularly in Africa. As the ICRC states, ‘common sense would suggest that such rules, and the limits they impose on the way war is waged, should be equally applicable in international and non-international armed conflicts’.3 The work of the ICRC informs state organs, international and national judicial bodies and international organizations of the contemporary legal regulation of armed conflicts. In doing so it provides both clarity and certainty for those involved. This is one example of how the theoretical study of international law profoundly impacts the practice of those in the field, and clearly does so for the better.

Whilst academic works are generally considered to be subsidiary sources of law in so far as they induce customary rules or general principles from state practice or national legal systems, it cannot be denied that in practice they often have a greater impact. Some works are referred to as ‘shorthand’ for the rules they elucidate; put another way, they in effect usurp the rule itself. States, courts and international organizations no longer refer to the pertinent state practice as evidence of the rule, but instead to the academic work itself. The commentaries on the ILC articles on the responsibility of states are one notable example.

This is a work of mapping, that is of locating the rules of international law. Nino would call it the work of ‘a geographer sitting behind a desk and carrying out research and analysis’. But, the law is not and cannot be like a geographical location. It has to be more; it has to evolve and to address the changing needs of society. Thus, both academic work and the work of the practitioner (and here the lines get blurred) have sometimes to cross the line between the elucidation of unwritten or written rules and the progressive development of the law. As Oscar Schachter noted, in this respect, academic work ‘plays a role in the process of creating new law and in extending existing law to meet emerging needs’.4

Let me continue with a further example.

This is the now well-known concept of jus cogens norms. As many of you will be aware, Articles 53 and 64 of the Vienna Convention on the Law of Treaties provide that treaties that conflict with peremptory norms of international law — jus cogens norms — are void. This was the first time the concept was enshrined in conventional law and has since been referred to numerous times by the ICJ. However, the inclusion of the concept was not the result of a meticulous study of state practice by delegates to the Vienna conference or the ILC. Rather it was the acquiescence of states to the idea that a higher order of norms exist, an idea which had been first propounded by legal academics.5

This concept dates back to the legal scholarship of the 19th century, when it was used by Georg Friedrich Puchta in his book Lehrbuch der Pandekten[Textbook of the Pandects or the Digest of Roman Law], a mid-19th-century German textbook on Roman and private law. The first truly comprehensive treatment of the topic took place in 1966 at a conference held by the Carnegie Foundation in Lagonissi, Greece.6 At this conference, various celebrated academics — Georges Abi-Saab, Boutros Boutros-Ghali, Georg Schwarzenberger, Eric Suy and Michel Virally, amongst them — discussed the concept of jus cogens, including its legal basis. What is notable, if one looks through the report of the conference, is the lack of a comprehensive study of domestic law and the total absence of an examination of state practice. Instead, the conference delegates traced the origins of the concept to scholarly literature and detailed the sparse references to it in the practice of international courts and tribunals. Around the same time as the Lagonissi conference, the inclusion of the concept appeared as Article 50 of the 1966 ILC draft articles on the law of treaties, which provided that a treaty was void if it conflicted with a peremptory norm of international law. This was retained, in a slightly modified version, as Article 53 of the Vienna Convention.

3. The Human Dimension of International Law

A much better example may be found in what Nino referred to as ‘The Human Dimension of International Law’. Law is a peculiar discipline, unlike much of the humanities or the arts or the sciences. This is because the study of law is inextricably linked to the purpose that law fulfils in society; we study law so we can understand how it may be used to better order society. We do not, of course, often acknowledge that this is the reason we engage in legal scholarship. But I believe that the study of law is an inherently purposive enterprise, whether we recognize that explicitly or not. This means that how we view the role of law in society necessarily has an impact on how we approach legal scholarship. Consider, for example, the following quote from Nino:

I still believe that only those problems that dramatically affect the daily life of human beings are worth studying. I still believe that it is the cluster of legal rules and institutions that may have a dramatic impact on the life and suffering of human beings that should constitute the main focus of our attention as scholars.7

It does not require me to tell you that Nino’s work on human rights and international criminal law was therefore a result not only of his academic interest but of his deeply held conviction that international law was there to serve the purpose of protecting individuals from the evils of other human beings. If one reads the Tadić Interlocutory Appeal decision closely, one phrase particularly stands out, and it was one that Nino must have placed there: hominum causa omne jus constitutem est, all law is created for the benefit of human beings.8 This was also a reflection of what Nino referred to as ‘il desiderio di aiutare gli altri’.

Nino’s view of the purpose of international law was in absolute accordance with the transformation of international law over the course of the 20th and 21st centuries. At the dawn of the 20th century, international law used to be law made by western European states for western European states; it was a jus publicum Europaeum. Individuals were only important in so far as the state, as a legal entity, decided to exercise diplomatic protection of its citizens to protect its own rights. This perpetuated the fiction that it was the state and not the individual that had been wronged. Since that time, international law has transformed from a system in which states have the discretion to protect individuals to one in which individuals can directly enforce their rights against states.

The first signs of movement away from the state-centric approach to international law occurred under the League of Nations when individuals were given the right to petition the Permanent Mandates Commission, the international body charged with supervising the mandate system. Although not envisioned by the Covenant, the League started receiving complaints against the mandatory powers, predominantly in relation to British and French mandates in the Middle East.9 Despite the mandatory powers initially playing a role in responding to petitions, the Commission eventually wrestled the power of review away from the mandatory with some success: over the 26-year life of the League, a total of 3044 petitions were submitted, 565 of which were partially granted.10

One of the most prolific authors of these petitions, particularly with regard to the peoples of the Mandates Territory of Togoland, was Mr Casely Hayford. Since you may not have heard about him, let me say a few words about this great African lawyer. Casely Hayford was born on 29 September 1866 in Cape Coast, in the British Gold Coast colony, now Ghana. In 1893, he travelled to London in order to study as a barrister at the honourable society of the Inner Temple, and at Peterhouse, Cambridge. He was called to the Bar in 1896. He returned that year to the Cape Coast to engage in private law practice.

Hayford gradually became heavily involved in the political movement for the emancipation of the peoples’ of West Africa. He was one of the founders of the Pan-Africanism movement and authored a novel called Ethiopia Unbound. He used his legal training to defend African causes before the British courts and the Mandates Commission of the League of Nations, and he published a number of legal works on the rights of colonized peoples in West Africa.

We have seen that the League of Nations system of petition started the institutionalization of individual rights vis-à-vis states in international law. This was in part thanks, among others, to the tireless work of Casely Hayford as a practitioner. But more than this, the most significant change in international law was undoubtedly the evolution of the rules that protect individuals and peoples. In terms of the right of peoples, the transformation of the principle of self-determination into a right to self-determination stands out as being of particular importance. We know that this ‘evolution’ was triggered by General Assembly Resolution 1514 (XV) of 1960. This resolution declared that colonization, foreign occupation and alien domination were a breach of the equal rights of peoples and thus contrary to the United Nations Charter. It also gave peoples the corollary right to determine their political status and destiny free from external pressure. The right to self-determination was subsequently recognized in the Declaration on Friendly Relations, which stated that colonial situations and conflicts lay outside the ambit of domestic affairs, thus bringing subjugated peoples and their rights within the scope of international law.

Any lingering doubt regarding the ability of peoples to bear rights under international law was dispelled by the ICJ in its Namibia Advisory Opinion of 1971,11 a view which it reiterated a few years later in the Western SaharaAdvisory Opinion when it described self-determination as a ‘right of peoples’,12 and affirmed that peoples could be the bearers of rights and obligations under international law. But if this was the work of the practitioners, let us now ask about the role of academics; in what way did theycontribute to the evolution of international law in this field?

4. The Algiers Declaration of 1976

Let me give you here the example of the 1976 Algiers Declaration on the Rights of Peoples, drafted by a group of intellectuals, including Nino, whose professed aim was to create the ‘Magna Carta of Peoples’.13 The Algiers Declaration was innovative in several respects. First, it went further than other instruments by recognizing that self-determination had both ‘internal’ and ‘external’ elements. Self-determination was not purely to be understood as freedom from foreign domination but also as the right to elect a representative government. The Algiers Declaration extended the right of peoples, in particular the right to self-determination, to other corollary rights, such as the right of peoples to freely choose the form of economic development that they desire, which was subsequently recognized by the General Assembly in its 1986 Declaration on the Right to Development. Thus, although not binding upon states, the Algiers Declaration has had a profound impact on the path of international law. One specific example would be in the development of human rights in Africa. The Declaration inspired what has now become the African Charter on Human and Peoples’ Rights, which is the only regional human rights instrument to place such an emphasis on the rights of peoples.

What motivated these intellectuals to draft this Declaration, which had a lot of influence in the subsequent development of international law in this area?

According to Nino:

[T]the United Nations tends to protect, in general, only certain categories of peoples: the ‘dependent peoples’, i.e. the peoples subjected to colonial domination or foreign occupation, and among the sovereign peoples, only those who live under a racist regime: the other peoples who live within sovereign states do not benefit from the care of the United Nations, even when they are oppressed, exploited, or brutalized by their governments.

He was referring to internal self-determination and the right of peoples to a representative government. Steadily, the rights recognized in these and other instruments — such as the International Covenants on Economic, Social and Cultural Rights (ICESCR) and on Civil and Political Rights (ICCPR) — have transformed the landscape of international law, moving it away from the state-centric model of European public law that characterized the international law of the 19th century. Contemporary international law recognizes that law must protect and serve individuals. Whilst the state still plays an important role in the creation and enforcement of international law, the fact that international law now recognizes the rights of individuals, and in many cases establishes mechanisms through which they can address their grievances directly against states, shows that it has reoriented itself towards the most fundamental building block of society — the individual human being.

Twenty years after the Algiers Declaration, Nino was able to write on internal self-determination that: ‘A contention could perhaps be warranted that at the present time a customary rule on the subject is in statu nascendi that is in the process of formation.’ Indeed, in the meantime an African Charter on Human and Peoples’ Rights was adopted and came into force in 1986. This Charter, which devotes six articles to peoples’ rights, recognizes the internal right to self-determination. This led the African Commission on Human and Peoples’ Rights to make the following statement: ‘There is a school of thought which believes that the right of a people in Africa can be asserted only vis-à-vis external aggression, oppression or colonization. The Commission holds a different view that the African Charter was enacted by African States to protect human and peoples’ rights of the African peoples against both external and internal abuse’. This vindicates the viewpoint propounded by Nino and by the Algiers Declaration.

5. The Person Behind the Ideas

Nino’s conviction that the purpose of international law is to protect the individual indelibly influenced his approach to both scholarship and practice. In my view, this is inevitable. As individuals, we do not have a sharp dividing line in our professional lives between theory and practice. Instead, the two bleed into each other and affect how we approach international law in all aspects of life. Nino was probably the one international lawyer who recognized better than anyone else that international law was constituted for human beings, beyond the state (which, of course, remains its subject par excellence) or international organizations. This gave him a particular interest not just in the academic work and practical accomplishments of individuals but also in the personal lives that lay behind these achievements. In his view, understanding the person behind the ideas was not only necessary to comprehend their approach to law, but also in order to understand the impact that that person had on others, even after their passing.

In the Preface to Five Masters of International Law, in which he interviewed five eminent international lawyers about their professional and personal lives, Nino explained that he considered:

… the interviewees not only as prominent professionals who had excelled in their careers, but also as human beings of flesh and blood. This, I acknowledge, finds its underpinning in my belief that it is not true what Hegel (followed by the Italian philosopher Benedetto Croce) held, namely that in the end what matters is not the private life of human beings but their works, that only their works remain and only by their works can one gauge the value of their authors. For Hegel, once men have fulfilled their tasks, they are similar to empty hulls that fall away from their kernel. Instead, with respect, I think that their personal life is no less important, and once they have passed away much of that life remains in the minds as well as in the hearts of those who knew them.14

Our meeting here today testifies to the truth of this statement.

The precursor to Five Masters was a book also authored by Nino that documented an interview with the Dutch lawyer, Bert V.A. Röling, who served as one of the judges at the Tokyo war crimes tribunal. Röling was a learned man who took an interest in literature, philosophy and the sciences, whilst also participating regularly in a string quartet based in Groningen. It was his intellectual independence that allowed him to stand apart from more conventional jurists in both his academic work and judicial career, which greatly fascinated Nino.

One of the most notable features of Röling’s work was its progressive approach: he identified the ends that the law should serve in contemporary society — peace between states, the protection of combatants in times of war, and the economic and social progress of all nations — and urged international lawyers to create rules and institutions that better served these purposes. In this respect, Röling understood the dynamic nature of law and the ability of individuals to shape the evolution of the legal system: he viewed ‘law [not as] a constant in a community, but a function … . It ought to change with changes in views, interests, and power relations.’15

6. Conclusion

In an article Nino wrote on Röling, he stated that lawyers fell into different categories: they are either intuitive or reflective; innovative or mainstream; technicians or investigators of over-arching structures; geographers (those who map known territory) or explorers; and broad-brush painters or meticulous polishers16 Each of these categories tells us a little about how the lawyer being categorized approaches the relationship between theory and practice. A reflective, mainstream, technical geographer who meticulously polishes his or her thoughts may not be as disposed to enter into practice, or to go into action, as Luigi Condorelli would put it, as an innovative explorer. From what I have said before, it should be no surprise that Nino categorized Röling as an explorer.

For those of you that have not read Le Petit Prince, let me explain a little about explorers and geographers. During his journey, the eponymous little prince encounters a geographer hunched over his desk mapping his planet. The geographer is too important and busy to leave his office in order to see the towns and rivers and mountains that he details on maps. Instead, he relies on explorers to describe the outside world to him. That is the distinction that Nino wanted to capture when he drew the metaphor of geographers and explorers from Saint-Exupéry — those that map known territory versus those that explore the realms of the possible.

To me, it is clear that Nino was an innovative investigator of overarching structures, but one who never lost sight of the importance of his work making a real impact in the world. However, from all of the categories that he outlined, perhaps the one that best describes him is that of an explorer. Nino was not a ‘geographer’ willing to sit behind the desk taking notes on subjects that he had not seen and not experienced. He realized that it is the true calling of an international lawyer to affect peoples’ lives for the better. In his words, his forays into ‘real life’ enabled him ‘to escape the danger of the ‘intellectual’ who, as Albert Einstein once noted, “has no direct contact with life in the raw, but encounters it in its easiest form — upon the printed page”.’17

However, there is another distinction between geographers and explorers that finds a parallel in international lawyers. When talking to the geographer, what the little prince finds most startling is that the geographer refuses to record ‘ephemeral objects’ (such as the prince’s treasured flower back on his home planet) in his austere books because he wants to create works that are impervious to time. Many international lawyers do the same: they want to take a snapshot of the rules at a certain point in time, abstracted from the past and the future. They see their task as that of the geographer who maps immutable structures.

Happily, however, there are some international lawyers that, unlike the geographer, recognize the ephemeral nature of legal rules. They recognize that the rules exist only because and for the benefit of the society that they serve. They recognize that rules evolve, grow and fall into desuetude because of the changing needs of society. Most importantly, they recognize that it is their job to identify, propose and effect these changes in practice. Nino was one of these. He was not a geographer who sat behind his desk. For him, and for all of us, theory and practice are to a certain extent indissoluble: they are simply two manifestations of our personality.


1 L. Condorelli, ‘Nino Cassese and the Sparrow’s Feet’, in A. Cassese (ed.), The Human Dimension of International Law: Selected Papers (Oxford University Press, 2008) l.
2 J.-M. Henckaerts and L. Doswald-Beck, Customary International Humanitarian Law, Volume 1: Rules (Cambridge University Press, 2005) xxviii–xxix.
3 Ibid., at xxix.
4 O. Schachter, ‘The Invisible College of International Lawyers’, 72 New York University Law Review (1977–78) 217.
5 See generally, D. Costelloe, Legal Consequences of Peremptory Norms in International Law (Cambridge University Press, 2017), chapter. 1.
6 Carnegie Conferences on International Law, The Concept of Jus Cogens in International Law (Carnegie Endowment for International Peace, 1967).
7 A. Cassese, ‘Soliloquy’, in A. Cassese (ed.), The Human Dimension of International Law: Selected Papers (Oxford University Press, 2008) lxxi.
8 Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, Tadić (IT-94-1-A), Appeals Chamber, 2 October 1995, § 97.
9 A. Momirov, ‘The Individual Right to Petition in Internationalized Territories. From Progressive Thought to an Abandoned Practice’, 9 Journal of the History of International Law (2007) 203, at 217.
10 Ibid., at 221.
11 Advisory Opinion on the Legal Consequences for States of the Continued Presence of South Africa in Namibia, Advisory Opinion of 21 June 1971, ICJ Reports (1971) 3.
12 Western Sahara, Advisory Opinion of 16 October 1975, ICJ Reports (1975) 12, at 31.
13 A. Cassese, ‘La Portée politico-juridique de la Declaration d’Alger’, in A. Cassese and E. Jouve (eds), Pour une droit des peuples (Berger-Levrault, 1978) 64.
14 A. Cassese, ‘Preface’, in A. Cassese (ed.), Five Masters of International Law (Hart, 2011) v.
15 B.V.A. Röling, International Law in an Expanded World (Djambatan, 1960) x.
16 A. Cassese, ‘B.V.A. Röling – A Personal Recollection and Appraisal’, 8 Journal of International Criminal Justice (2010) 1141, at 1143–1144.
17 Cassese, supra note 7, at 1xviii.