While traditionally consent of states has played an important role in the determination of

sources of international law, we are witnessing more and more a gradual shift away from a

state centric approach. We live in a multi-polar international community comprising of in

excess of 200 states and, therefore, unanimous express agreement is no longer possible or

pragmatic as the ultimate source of all international legal norms.

The weakening grip of consent in international law can be seen on examination of the

hierarchy of sources presented in Article 38, which appoints a pivotal role to state consent in

accordance with the positivist theory. One can deduce the limitations of a theory epitomised

by state consent in modern times on further analysis of the enumerated sources of the article,

as well as those which are not mentioned yet still play an increasingly influential role in

modern international law-making.

The positivist view, as expressed by Brownlie, esteems that “State consent is the foundation

of international law. The principle that law is binding on a State only by its consent remains

an axiom of the political system, an implication of State autonomy.”1 Such an understanding

of the law goes along with early positivists such as Thomas Hobbes, Richard Zouche, Samuel

Rachel who all rejected natural law reasoning, instead asserting that the “law of nations...is a

law among nations, {which} consists of customs and treaties”, clearly a consent dominated

approach to the sources of international law.2

However, if one were to claim that a norm binds states because they consent to the norm’s

binding effect, that would lead to an infinite logical regression of states consenting to

consent. On the other hand, if one were to claim that a norm’s legal force derives from a non-

1Hollis, Duncan B., 'Why State Consent Still Matters: Non-State Actors, Treaties, and the Changing Sources of International Law', Berkeley Journal of International Law, Vol. 23 (2005), p.5, quoting Ian Brownlie, Principles of Public International Law 4 (6th edition 1995)

2 Koh, Harold Hongju, 'Why Do Nations Obey International Law?’, Yale Law Journal, Vol. 106 (1977) at p.2608

consensual basis such as natural law, consent could not be the only basis for creating

international law.3

Gerald Fitzmaurice, drawing on the writings and lectures of other legal scholars, eschewed

strict reliance on either natural or positivist consent as sources of legal obligation claiming,

“As Verdross, Brierly and others have conclusively shown, it is not consent, as such, that

creates the obligation...the real foundation of the authority of international law resides...in the

fact that States making up the international society recognise it as binding upon them, and,

moreover, as a system that ipso facto binds them as members of that society, irrespective of

their individual wills.”4 Thus, the basis of compliance to the sources of international law is

not because the sources have been consented to, but because they are recognised as binding in

nature. This concurs with D'Amato's conclusion that international law is “real law”, an

assertion which goes against state centrism and a consensual theory to international law.5 One

could subscribe to D’Amato’s belief that there is no basis for a consent based approach to

international law6.

When assessing whether consent is the ultimate source of international law, Kammerhofer

deems the “fountainhead”7 of any deliberation to be Article 38 of the Statute of the

International Court of Justice. According to the article, the principal sources of law are

3Supra note 1, at p.6

4 Supra note 2, at p.2613 quoting Gerald Fitzmaurice, The Foundation of the Authority of International Law and the Problem of Enforcement, 19 Modern Law Review 1 (1956) at p.8

5 D'Amato, Anthony, 'Is International Law Really “Law”?', Northwestern University Law Review, Vol. 79 (1984-1985) 1293

6D'Amato, Anthony, 'On Consensus', The Canadian Yearbook of International Law, Vol. 8 (1970)

7Kammerhofer, Jorg, 'Uncertainty in the Formal Sources of International Law: Customary International Law and Some of its Problems', EJIL, Vol. 15(3) (2004) at p.541

deemed as treaty law, customary law, and “general principles of law”, with judicial decisions

and the works of publicists being relegated to a secondary level.8

We have witnessed the favouring of treaties as the manner of creation of international legal

norms in recent times. Treaties are, by their very nature, consent based. If a rule is laid down

in a treaty, then it is binding on all States parties to that treaty, and the treaty is at once the

formal and material source of the rule.9 It is crucial to the consent theory that a State which is

not party to a treaty is under no obligation. As the 1969 VCLT states, ‘A treaty does not create

either obligations or rights for a third State without its consent.’10

However, this consent based approach to treaty law is not a hard and fast rule and the strictly

positivist view of state consent as the ultimate basis of treaty law has been somewhat eroded

with the expansion of international law. It is no longer the case that it is “made” by a finite

number of states through a handful of intergovernmental processes.11 Although states remain

the primary makers of international law, globalisation has diminished the importance of their

sovereignty with the effect that other actors such as NGOs have become increasingly

influential players in the creation, implementation and enforcement of international law.12

Despite the fact that the status of NGOs in international law has not progressed, Martens

points to various studies which have shown the important role that NGOs can play in the

8 Joyner, Christopher C., 'U.N. General Assembly Resolutions and International Law: Rethinking the Contemporary Dynamics of Norm-Creation', California Western International Law Journal, Vol. 11 (1981) at p.455

9Evans, Malcolm D., International Law, 6th Edition, Oxford: Oxford University Press, 2003

10 Supra note 9

11Pronto, Arnold, 'Some Thoughts on the Making of International Law', EJIL Vol. 19(3) (2008) at p.601

12 Supra note 1, at p.37

process of establishing new international standards or modifying existing international law

according to evolving criteria.13

A strict consent orientated approach to the sources of international law is clearly limited in

this regard. Such a state centric theory would exclude non state actors, despite their

increasingly prominent role in international law.14 Certain scholars argue that the growing

participation of non-state actors in the law making process does not undermine a consent

based approach to treaties. As Hollis notes, “These non-state actors are creatures of state

consent, and may in many cases require their continuing consent to operate which suggests

that it is premature to disregard the old state-centric paradigm.”15 However, Susan Marks

makes the valid point that, “When we counter pose the non-state to the state, we tend to

obscure the extent to which each is already present within the other, governing its existence

and defining its meaning. The two phenomena are made to appear separate, when in reality

they are enmeshed.”16 Therefore, the non-state actor is inherently present in the treaty-making

process and so, one has so question the reliance on a purely state centric consent based

approach.

Another stumbling block to a purely consent based theory of treaty law is the issue of treaty

interpretation; the trend of going beyond the primary text of the treaty by means of

incorporation of extraneous legal rules. The relevant Article 31(3)(c) of the Vienna

Convention is deemed to be “sound and undisputed in principle as far as treaty interpretation

13Martens, Kerstin, 'Examining the (Non-) Status of NGOs in International Law, Indiana Journal of Global Legal Studies, Vol. 10 (2003) at p.6

14Marks, Susan, 'State Centrism, International Law, and the Anxieties of Influence', Leiden Journal of International Law, Vol. 19 (2006) at p.340

15Supra note 1, at p.38

16 Supra note 14, at p.341

is concerned”.17 Such treaty interpretation touches upon the delicate issue of the consensual

nature of international law as the concept of objective revision allows, and potentially even

requires, a tribunal to impose an altogether new meaning on a term or provision because of

the way the law has subsequently changed. Unless one is prepared to accept the highly

speculative argument that States have agreed to such objective revision by virtue of some rule

in general international law, such objective revision undermines the notion of consent, both at

the treaty adoption stage and, subsequently, during the dispute settlement.18

A purely consent based approach to international law is clearly not sufficient in today’s

modern, evolving world. In interpreting treaties, the judiciary have to incorporate recent

developments, as it considers such developments so significant that they must inevitably form

part of the interpretation of a pre-existing text. The inclusion of references to extraneous law

is also likely to encourage a more coherent approach to legal reasoning and prevent

disintegration of legal rules into their various sub-disciplines. They also permit a tribunal to

ensure that the narrow application of a rule is not allowed to overrule broader notions of

justice.19 Article 31(3)(c) has served to erode the strict positivist conception of international

law by allowing the Court to apply principles which do not hold their origin in either custom

or treaty form, although they may later become embodied in such.20

Custom is regarded as a formal source of law under Article 38 and founded on the basis of

consent. Mere fact of consistent international practice in a particular sense is not enough, in

itself, to create a rule of law. Opinio Juris is the centrepiece of customary international law

17French, Duncan, 'Treaty Interpretation and the Incorporation of Extraneous Legal Rules', International and Comparative Law Quarterly, Vol. 55 (2006)

18 Ibid

19 Ibid

20Dixon, Martin, Textbook on International Law, 6th Edition, Oxford; New York: Oxford University Press, 2007 at p.43

for consent-based theorists, namely the subjective element that what you are doing amounts

to law.

Custom is regarded by some as a form of tacit consent.21 States behave to each other in given

circumstances in certain ways, which are found acceptable, and this tacitly assented to, first

as a guide to future conduct and then, little by little, as legally determining future conduct.22

As Raphael Walden put it, “The tacit consent theory, an all its forms, has the great merit of

recognising the constitutive nature of custom”.23

In recent years this position has found advocates among Soviet jurists who have seized upon

the notion of strict consent as a way to “pick and choose among the norms of international

law”. “Agreement is the essence of custom” in that it expresses the “will of a state” to

“consent” to a rule and thus become bound by it. MacGibbon and Fitzmaurice uphold this

view with Fitzmaurice proclaiming in the oft-cited quote: “Where a general rule of customary

international law is built up by the common practice of states...it is probably true to say that

consent is latent in the mutual tolerations that allow the practice to be built up at all; and

actually patent in the eventual acceptance of the practice, as constituting a binding rule of

law.”24

However, state practice in this area has demonstrated obvious contradictions with a theory of

tacit consent to explain custom. One such contradiction of a consent based theory is that it is

21 Supra note 9

22 Supra note 9

23 Supra note 7, at p.533 quoting Walden, 'The Subjective Element in the Formation of Customary International Law, 12 Israel Law Review (1977) 344, at 355

24D'Amato, Anthony, The Concept of Custom in International Law, Ithaca, N.Y., Cornell University Press, 1971 at p.187 quoting Fitzmaurice, 'The Law and Procedure of the International Court of Justice, 1951-1954: General Principles and Sources of Law', 30 BYIL 1, 68 (1953)

generally recognised that a rule of general CIL is binding on all States, whether or not they

have participated in its development, and so shown their assent to the rule. 25 In reality, most

states neither consent nor protest to developments. Can such silence or acquiescence really be

held to equal consent?26 The truth is that claiming that the doctrine of tacit consent can be the

ultimate basis of obligation in customary law has always involved a fiction, for it requires us

to assume from the mere fact that a rule is observed and treated as obligatory that those who

recognise its obligatory force have consented to it, and this may or may not be true in fact.27

If the consent theory were truly an expression of an individual state’s will to be bound, logic

would require that if a state changes its mind it would cease to be bound. However, this is not

the case in international law. 28 The result would be to wipe out the very notion of law. Such

a change of mind would appear logically to be precluded by consent theory as a basis for how

nations become obligated, and yet would seem to be required by the predominance of the

will.29 Contrary also to this logic also is the fact that if the particular individuals who

expressed a state’s consent are overthrown in a revolution or defeated in the next election, the

consent is not revoked. Treaties persist, as well as the state’s obligations to the general body

of customary international rules. 30

.

Louis Jaffe wrote in 1933 that “consent is given in international law as a system rather than to

25 Supra note 9

26Supra note 7, at p.533

27Brierly, James Leslie, The Basis of Obligation in International Law and Other Papers, edited by Sir Hersch Lauterpacht and C.H.M. Waldock, Scientia Verlag Aalen, 1977 (Reprint of the edition Oxford 1958) at p.13

28Supra note 24, at p.191

29Supra note 5, at p.1309

30Supra note 24, at p.191

each and every relationship contained in it”31. If the individual consent theory were valid, one

would be compelled to assert that a new nation is not bound by any particular rule of

international law until it has consented to that rule. The new nation can then pick and choose

among the rules those that it likes. This pick-and-choose position is clearly wrong as a matter

of historical fact as well as logic.32

Thus, it is clear that a purely consent based approach to customary international law is open

to many gaping loopholes. A customary rule is observed, not because it has been consented

to, but because it is believed to be binding.”33 In a recent study of state practice, Richard Falk

concludes that the alleged requirement of presumed consent in customary law must be

dropped. Consent is a vertical verbal rationalisation that in Falk’s analysis does not accord

with the primarily horizontal ordering of authority and power among independent states in

the international system.34

Jus cogens has served to further weaken the positivist approach with consent as the ultimate

basis of international law. These peremptory norms are deemed so fundamental to the public

order of the international community that they are potent enough to invalidate contrary rules

which might otherwise be consensually established by states, through treaties or custom.35

Once ensconced, it is beyond state control and cannot be amended by treaty or by their

31Ibid, at p.188 quoting Jaffe, Judicial Aspects of Foreign Relations 90 (1933)

32Supra note 5, at p.1309

33 Supra note 6, at p.114 quoting Brierly, The Law of Nations 53, 5th edn. 1955

34Supra note 24, at p.191 drawing from Falk, The Role of Domestic Courts in the International Legal Order 171 (1964)

35 Janis, Mark W., 'The Nature of Jus Cogens', Connecticut Journal of International Law, Vol. 3 (1987-1988) at p.359

practice.36 They may only be modified by the creation of another rule which is also of a jus

cogens nature. Historically, it is significant the proponents of the idea of peremptory norms

invalidating treaty rules were reacting to the abuses of Nazism during the Second World

War.37 They rejected the positivist proposition that state acts, even the making of treaties,

should be always thought of as making binding law. The doctrine of jus cogens is thus

reflective of the “deeply felt need of the increasingly interdependent global community for a

public order for all mankind.”38 On these facts, jus cogens represents a challenge to the

traditional notion of state sovereignty in the sense that the general will of the international

community of states will take precedence over the individual wills of states. The evolution of

jus cogens can be seen as a movement away from viewing states as unrestricted total

sovereigns which is deemed “a mockery, not a fulfilment, of the deepest aspirations of

humanity.”39

Uncertainty abounds as to the source of such peremptory norms. It is unclear whether they

constitute a wholly new source of law or a product of the existing sources under Article 38.

Either way, the doctrine of jus cogens represents a challenge to the core of the positivist

argument of state consent as the ultimate basis to the sources of international law. Indeed, in

the wake of the acceptance of the doctrine, some called for “reconsideration of the positivist

36 Ibid, at p.362

37 Ibid, at p.361 drawing from E. Jimenez De Arechaga, El Derecho Internacional Contemporaneo 79 (1980)

38 Danilenko, Gennady M., 'International Jus Cogens: Issues of Law-Making', EJIL, Vol. 2 (1991) at p.64

39 Turpel, Mary Ellen & Philippe Sands, 'Peremptory International Law and Sovereignty: Some Questions', Connecticut Journal of International Law, Vol. 3 (1987-1988) at p.369, quoting Jenks, Law in the World Community 34 (1967)

theory.”40 Norms of a peremptory nature bind the entire international community, even

dissenters41, and thus, consent cannot be claimed to be the bedrock of international law.

.

Yet another challenge to a strictly consent based theory as to the sources of international law

is the emergence of instruments such as the resolutions of the UN General Assembly.

Although General Assembly resolutions are not binding on member states, as early as 1951,

the late Judge Alvarez went so far as to posit that “the {General} Assembly of the UN is

tending to become an actual legislative power.” Developing countries have chosen the global

forum of the United Nations system in general and its General Assembly in particular to

achieve active participation in the creation and application of contemporary international

legal standards, as their group of 77 states hold the majority position among the 120 states.42

It is evident that the acceptance of such resolutions as being sources of international law

would clearly go directly against the positivist state consent based theory. With no express

mention in Article 38, however, ostensibly the logical deduction to be drawn is that General

Assembly resolutions cannot be construed as a formal source of law.

On deeper analysis, this reasoning may prove flawed when one considers that in actual

practice, in reaching a decision the Court has sought to include non-Article 38 factors,

counting among them, General Assembly resolutions.43 Modifications in international law

40 Supra note 38, at p.44

41 Ibid, at p.50

42 Supra note 8, at p.446

43 Ibid, at p.455

may become imperative due to shifting community values, the impact of technology or

obvious lacunae in existing law. It is in these broad areas that General Assembly resolutions

have manifested their greatest note-worthy legal impact.44 It's impact in one such

contemporary issue regarding The Common Heritage Of Mankind clearly highlights the

growingly significant role which General Assembly resolutions play in influencing and

shaping the course of international law's modern direction,45 leading one inevitably to

question the foundations of a theory of the sources of law being based ultimately on state

consent and a positivist reading of Article 38.

.

The doctrine of sources has served international law well over the past century, providing

structure and coherence during a time when international law was expanding rapidly and

dramatically.46 However, the hierarchy of sources articulated in Article 38 no longer provide a

“complete and unambiguous statement of the sources of international law”.47 Sir Robert

Jennings esteems that it is “an open question whether {Article 38} is now itself a sufficient

guide to the content of modern international law”.48 The traditional hierarchy of treaties,

custom and general principles, with its focus on formal sources and state consent, was

designed to explain a turn-of-the-twentieth-century world of few states and state-coordinated

44 Supra note 8, at p.462

45 Ibid, at p.477

46Cohen, Harlan Grant, 'Finding International Law: Rethinking the Doctrine of Sources', Iowa Law Review, Vol. 93 (2007) at p.65

47 Supra note 20, at p.24

48 Supra note 1, at p.6 quoting Jennings, 'What is International Law and How Do We Tell It When We See It?', Schweitzerisches Jahrbuch Fur Internationales Recht 37, 60 (1981) reprinted in Sources Of International Law 28 (Martti Koskenniemi ed., 2000)

treaties. But in a world marked by a multiplicity of states and human rights treaties with deep

implications for the internal affairs of states, the hierarchy and those sources are dogged with

inadequacy49 and have left international law plagued with uncertainty.50 The idea that a state

is not bound by a rule of international law unless it has previously consented to that rule is an

extreme form of the positivist tradition in international jurisprudence in the nineteenth

century. Its proponents, in Lauterpacht’s words, had an “exaggerated regard for

sovereignty”.51 The need for acceptance of a more flexible approach to international law-

making is apparent and it is clear that one can no longer subscribe to Wright's assertion that

state is the ultimate source of international law.52

49 Supra note 46, at p.69

50 Supra note 7, p.523

51Supra note 24, at p.187 quoting Lauterpacht, 'Decisions of Municipal Courts as a Source of International Law', 10 BYIL 65, 83 (1929)

52 Supra note 6, at p. 110 quoting Wright, 'Custom as a Basis for International Law in the Post-War World', 2 Texas International Law Forum 147, 158 (1966) at p. 153

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