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� EJIL 2003
* Professor of International Law, Graduate School of Law and Politics, University of Tokyo. The author
owes a debt of gratitude to many people who kindly read earlier versions of the manuscript, including the
Japanese version, and gave him useful comments: Professors Robert Keohane, Benedict Kingsbury,
Nicholas Onuf, Sakamoto Yoshikazu, Bruno Simma, Brigitte Stern, Tanaka Akihiko, Yokota Yozo,
Watanabe Akio, and many others including the anonymous referees of the European Journal of
International Law. He is also grateful to Messrs Walter Hutchinson, Gerardo Vildostegui and his graduate
students, especially Toyoda Tetsuya and Kaku Shun, for proofreading the manuscript and assisting him
in checking references.
Please note that Onuma is the author’s family name. This ordering of names is common to Japanese,
Korean, Chinese and many other languages.
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EJIL (2003), Vol. 14 No. 1, 105–139
.............................................................................................
International Law in and with
International Politics: The
Functions of International Law
in International Society
Onuma Yasuaki*
Abstract
International law has conducted and still conducts distinctive societal functions based on the
general understandings and perceptions of law. In this article, I first quickly glance at two
disciplines, international law and international relations, and see how they have developed as
separate disciplines, scarcely learning from each other until recently. In the second section, I
deal with the longstanding debates on the binding force of and compliance with international
law from a functional perspective. In the third section, I seek to demonstrate that although
bindingness is the primary function of international law, the raison d’être of international
law must be explained by means of more comprehensive perspectives. In the final section, I
indicate functions other than the binding one, and seek to elucidate how they carry out
important societal functions which non-legal norms, such as ethics, morality and religion, as
well as policies or politics, cannot fulfil. In this way, I seek to explore the raison d’être of
international law in terms of its societal functions, in comparison with those of international
politics (or policies) and international ethics (or morality), by analysing four functions of
international law: binding, communicative, value-declaratory, and justifying and
legitimating.
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106 EJIL 14 (2003), 105–139
1 To deal with the functions of international law in international society, we have to deal not only with
phenomena relating to international law understood as law between nations (actually governments),
but also those relating to international organizations, private companies and NGOs, private international
law, state laws, relations between domestic politics and international law and other related questions.
Further, as will be shown in the text, international law is diverse. Therefore it is impossible to talk about
the role of international law in universal and trans-historical terms. The same is true with international
politics. However, for the sake of simplification of the discussion, which is needed as a first step to a more
complicated theory, I will deal with the subject assuming the general perception of international law and
politics prevalent in international society basically in the late twentieth century. The argument in this
article will thus be state-centric (as to the need for the revision of the state-centric approach, via
introduction of transnational and intercivilizational perspectives, see Onuma, ‘Towards an Intercivil-
izational Approach to Human Rights’, 7 Asian Yearbook of International Law (2001) 21, at 30–31,
77–81). The term international relations is used to refer both to the discipline in the US dealing with
international political phenomena and to international political phenomena themselves.
2 J. Austin, The Province of Jurisprudence Determined (Weidenfeld and Nicolson ed., 1954, reprint, 1998)
127, 140–142.
3 See, e.g., H. Kelsen, Principles of International Law (2nd ed., 1966) 3, 570–571.
4 See, e.g., H. Morgenthau, Politics among Nations (rev. 5th ed., 1978) 219–298.
Introduction
The question of the societal functions which underpin the raison d’être of
international law, in comparison with those of politics (or policies) and ethics (or
morality) in international society, is one which merits elaborate theorizing by both
international lawyers and international relations scholars.1 As suggested by the
repeated assertion that a particular issue is not a problem of law but rather of politics
(or policy), international law has often been dealt with in relation to, or in comparison
with, international politics or policy, although in most cases this has occurred in a
tacit and/or unconscious manner. Moreover, international law has, either explicitly
or tacitly, been dealt with in relation to, or in comparison with, international ethics or
morality. This is evidenced by John Austin’s claim that international law is not law in
the proper sense of the term but positive morality.2 Similarly, Hans Kelsen and other
leading lawyers have undertaken comparisons of (international) law and (inter-
national) ethics or morality, and have sought to distinguish the former from the latter
by means of various criteria.3 So too, the place and function of international ethics
and/or morality have at times been explored by international relations scholars,
either explicitly or implicitly, together with those of international law.4
Nevertheless, the question of the raison d’être of international law, in terms of what
societal functions international law, international politics and international ethics or
morality can and do fulfil, respectively and by comparison, has not been the subject of
sufficient investigation. When international lawyers argue that a particular issue is
not a problem of law but of politics or policy, there is a tendency on their part to simply
abandon any further professional or scholarly exploration of the question. There is an
assumption that the problem should be taken up by international relations scholars.
However, there is no guarantee that this is actually the case. The claim that a certain
issue is not a problem of law but of politics or policy has often been used as a magic
wand by international lawyers to wave away their professional responsibility.
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International Law in and with International Politics 107
5 See, e.g., my remarks criticizing a peculiarly domestic-oriented understanding of international law in the
US in comparison with the understanding of international law in other nations, Onuma, ‘Remarks’, 75
Proceedings of the ASIL (1982) 163–167.
6 See, e.g., H. Lauterpacht, The Function of Law in the International Community (1933); G. Schwarzenberger,
Frontiers of International Law (1962), at 21–42; H. Kelsen, supra note 3, pt. III; W. Coplin, The Functions of
International Law (1966), esp. at 4–7; H. Bull, The Anarchical Society (1977), at 140–142; Abott, ’The
Trading Nation’s Dilemma’, 26 Harvard ILJ (1985) 501, at 521–532; Johnston, ’Functionalism in the
Theory of International Law’, Canadian YIL (1988) 3.
7 Lauterpacht, supra note 6.
8 Kelsen, supra note 3, pt. III.
9 Although Kelsen, supra note 3, calls Part III of his book ‘The Essential Function of International Law’ and
assigns 130 pages to this part, he does not use the term ‘function’ in the actual analysis. Brownlie has the
same problem. Although Chapter 1 of his book, The Rule of Law in International Affairs (1998), is entitled,
‘The Function of Law in International Community’, he does not deal with the problem of function in an
elaborate manner. It is difficult to know what his ‘function’ means.
In this author’s view, international law has conducted, and continues to conduct,
distinct societal functions based on a general understanding and perception of law.
Like state law, which has assumed various forms and has played various functions
according to country, time period, traditions and societal structure, international law
is diverse. There are a variety of international laws, depending on forms or ‘sources’,
the particular area they are supposed to regulate, the way they are understood and
perceived in different countries and in different historical periods, and so on.5 The
functions of international law differ in relation to different conditions and circum-
stances. Further, the term ‘function’ is itself equivocal. Disagreements over the theory
of functions of international law depend basically on which aspect of these diverse
international laws a researcher may seek to analyse. If we understand the ‘essence’ of
law as the realization of justice, we may think that a major function of international
law is to provide a tool for achieving international justice. If, on the other hand, we see
the role of law as that of camouflaging the dominance and exploitation by the
establishment of a society, then a major function of international law can be seen as
that of justifying global dominance and exploitation by the powerful developed
countries.
Many authors have written interesting pieces on the function of international law,
but their terminology differs greatly.6 When Hersch Lauterpacht wrote his renowned
The Function of Law in the International Community, his ‘function’ meant nothing other
than judicial function.7 For Kelsen, the ‘essential function’ of international law was to
determine the spheres of validity of the national legal orders, including the
determination of their territorial, personal, material and temporal spheres of validity.8
Although many authors have referred to the ‘essential’ or ‘specific’ function of
international law, it is not always clear what they have in mind as comparative
referents.9
The function of international law in this article will be analysed in terms of societal
roles which international law has played in comparison with the societal roles of
politics or policies and those of morality or ethics in international society. The analysis
is not in terms of a substantive function, such as allocating territorial jurisdiction,
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108 EJIL 14 (2003), 105–139
10 Onuf argues that bindingness is a property, not a function, of law (Comment on an earlier version of this
article, 24 January 2002). An anonymous referee also suggested that bindingness is a quality rather
than a function of law. It is true that law has been preeminently defined as a binding norm, and
international law has benefited from this prevalent definition as well as the prevalent image based on this
definition, as I myself argue in the text. However, this does not mean that we cannot, and should not,
observe bindingness from a functional perspective. We might be able to say that it is better to grasp
bindingness as a property or a quality than to grasp it as a function of law (whether one takes this
position or not depends on his/her purposes, philosophy and other factors). However, we cannot say that
bindingness is a property or a quality of law, and that therefore we should not grasp it from a functional
perspective. Bindingness can be grasped as a function, together with other functions such as
communicating, and justifying or legitimating. I am ready to admit that the binding function is the
primary function of law, and other functions are secondary, at least partly based on the perception of law
as a binding norm. However, I do not believe that bindingness must be defined exclusively as a property
or a quality of law and that for that reason we cannot or should not grasp it from a functional perspective.
11 It is generally assumed that international law has another important function: settling conflicts between
nations. However, I have already dealt with that elsewhere (Onuma, ‘The ICJ: An Emperor without
Clothes?’, in N. Ando et al. (eds), Liber Amicorum Judge Shigeru Oda (2002) 191). In this article, I will
mainly deal with the binding function and other secondary functions enumerated in the text.
restricting the use of force and so forth. A major reason for this approach is that the
function of international law can be most clearly elucidated by comparing it with
those of politics (or policies) and morality (or ethics). Law, morality (or ethics) and
politics (or policy) are all useful social constructs and play roles which often overlap
and yet often differ from each other. Law and morality especially share common
features as norms, yet each has its own respective raison d’être. So too, law and
politics share common features associated with power, especially the power of a state,
yet they often contradict each other. Law is a tool of politics, but at the same time
politics is expected to be conducted within the framework of law. Thus, it is
meaningful and useful to compare functions of law with those of morality and of
politics.
In this article, I will first take a quick glance at two disciplines, international law and
international relations, and see how they have developed as separate disciplines,
scarcely learning from each other until recently. In the second section, I will consider
the longstanding debates on the question of the binding force of, and compliance with,
international law from a functional perspective. In the third section, I will seek to
demonstrate that although bindingness is the primary function of international law,10
the raison d’être of international law must be explained by more comprehensive
perspectives. In the final section, I will point to functions other than that of
bindingness, and attempt to elucidate how they carry out important societal functions
which non-legal norms, such as ethics, morality and religion, as well as policies or
politics, cannot fulfil. In this way, I will explore the raison d’être of international law in
terms of its societal functions, in comparison with those of international politics (or
policies) and international ethics (or morality), by analysing four functions of
international law: the binding, communicative, value-declaratory, and justifying and
legitimating functions.11
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International Law in and with International Politics 109
12 The Nordic Journal of International Law, The Finnish Yearbook of International Law and some other journals
have also carried interesting articles dealing with this issue.
13 54 International Organization (2000). Informative and stimulating studies have been carried out by
prominent international relations scholars, including K. Abott, G. Downs and D. Rocke, M. Finnemore,
J. Goldstein, A. Hurrell, P. Katzenstein, R. Keohane, S. Krasner, F. Kratochwil, J. Mearsheimer, N. Onuf,
J. Ruggie, S. Scott, K. Sikkink, B. Simmons, H. Suganami, A. Wendt and O. Young, since the late 1970s,
especially since the 1990s.
14 Slaughter et al., ‘International Law and International Relations Theory’, 92 AJIL (1998) 367, at 367. In
making this statement, they referred to A. Chayes and A. H. Chayes, The New Sovereignty (1995), at 2,
n. 3. However, what Chayes and Chayes said is somewhat different. They wrote that ‘Regime theorists
find it hard to say the “L-word”, but “principles, norms, rules, and decision-making procedures” are what
international law is all about.’ (Ibid.)
15 See Simpson, ‘The Situation on the International Legal Theory Front’, 11 EJIL (2000) 439, at 453, n. 43.
16 However, see criticism by David Kennedy of the prevalent tendency to deal with two disciplines, ‘The
Disciplines of International Law and Policy’, 12 Leiden Journal of International Law (1999) 9.
1 Previous Studies of International Law and International
Relations and Their Problems
During the last two decades, a number of international lawyers in the US and in
Europe have sought to bridge the gap between studies of international law and
international relations. Especially since the 1990s, both the American Journal of
International Law and the European Journal of International Law have published a
number of stimulating articles dealing with law and politics in international society.12
In 2002, the American Society of International Law hosted an Annual Meeting
entitled ‘The Legalization of International Relations/The Internationalization of Legal
Relations’. Some international relations scholars, especially institutionalists and
constructivists, have dealt with relevant treaties and decisions and/or resolutions of
international organizations in such fields as international trade, global environment,
disarmament, human rights and ‘humanitarian intervention’. International Organiza-
tion, a leading journal in the study of international relations, published a special issue
on ‘Legalization and World Politics’ in 2000.13
Writing in 1998, Slaughter et al. declared that ‘[o]n the IR side of the ledger, the “l
word” is no longer taboo’.14 I wish I could agree with them. However, judging from the
actual writings of international relations scholars, I am afraid that they are overly
optimistic. I take their words as an expression of their wish rather than their
observation of the actual state of international relations studies. Similarly, the
publications and debates on the part of international lawyers dealing with inter-
national relations have not been accepted by the majority of international lawyers.
The interest seems to be limited to a small number of enthusiastic scholars.15 Precisely
because the present tendency for international lawyers and international relations
scholars to seek mutual understanding is welcome and to be encouraged,16 research
covering their common fields should be carried out on each side with a sense of both
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110 EJIL 14 (2003), 105–139
17 The study of international relations in the US has a tendency to consume academic fashions within a
relatively short period of time. We have witnessed the rise and fall of many theories and approaches
including system theory, linkage politics, regime theory, interdependence theory, and so on. The
emerging interest in the role of norms by international relations scholars should not be one of these
fashions, particularly as propounded by a limited number of constructivists and institutionalists.
18 For criticism of this approach, see Onuma, supra note 11, at 205–207.
19 E. H. Carr, The Twenty Years’ Crisis (1964), pt. 4. George Kennan’s criticism of the moralistic and legalistic
approach (G. Kennan, American Diplomacy 1900–1950 (1951), Pt. 1, Ch. 6) is also famous. Hans
Morgenthau, who began his academic career as an international lawyer, became a leading figure in the
criticism of legalistic thinking in international affairs (Morgenthau, supra note 4, Ch. 1, at 11–14).
20 Hoffmann, ‘International Law and the Control of Forces’, in K. Deutsch and S. Hoffmann (eds), The
Relevance of International Law (1968) 21–46.
self-criticism and critical analysis of the other.17 In order to carry out this important
task, it is necessary to situate recent research and discussions in a wider perspective
that encompasses the history of both disciplines.
During the twentieth century, the positivists