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Sources Essay Notes
Starting point: Art 38 of the Statute of the International Court of Justice (ICJ), 1945

1. The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply:
a. international conventions, whether general or particular, establishing rules expressly recognized by the contesting states;
b. international custom, as evidence of a general practice accepted as law;
c. the general principles of law recognized by civilized nations;
d. subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rules of law.

2. This provision shall not prejudice the power of the Court to decide a case ex aequo et bono, if the parties agree thereto (i.e. to ignore the rules which are the product of any of the above 3 law-creating agencies and to substitute itself as the law-creating agency).
Note: Art 38 is technically limited to sources of international law which the International
Court must apply. However, there is no serious contention that it expresses the universal perception of the sources of international law, because

The function of the International Court is to decide disputes submitted to it "in accordance with international law"
All member states of the United Nations are ipso facto parties to Art 38 by virtue of
Art 93 of the united Nations Charter (further, states that are non-members of the UN
can specifically become parties to Art 38)
Many subsequent treaties and conventions, like UNCLOS 1982, refer to it.

1 Treaties
Article 38 refers to treaties as "international conventions, whether general or particular,
establishing rules expressly recognized by the contracting states"
The obligation to follow a treaty once has ratified is derived from CIL - the principle of pacta sunt servanda. See also Art 26, VCLT.
If the content of the treaty reflects CIL, then the rules of the treaty, not the treaty itself,
becomes binding upon all States, regardless of whether they are parties to the treaty. The CIL will also continue its separate existence (see below on the relationship between customs and treaties).
In the past, there was debate about whether or not treaty obligations amounted to international law. The German philosophical tradition was to treat treaties like contracts. It is not a legal system, merely an agreement.

Fitzmaurice argued that the only law that is relevant here - that the obligation must be carried out - which is derived from an antecedent general principle of law: pacta sunt servanda.
There might be treaties which codify existing law. But in those scenarios, the state parties to the treaty will not be following the treaty as much as it is following the law. The treaty is merely an instrument in which the law is conveniently stated and evidence of what it is,
but is not in itself law.
Even if a treaty obligation eventually becomes law, the treaty itself will not be the source of this new law: it will be custom, as more and more states practice the rule.

2 Custom
Article 38(1)(b), Statute of the ICJ: "international custom, as evidence of a general practice accepted as law"


For a new customary rule to be formed, there must be (i) relevant acts of the states concerned amount to a settled practice and (ii) opinio juris. These two elements are respectively an objective (behaviour) and subjective (belief) criterion.
 Nicaragua v USA
Facts and verdict: Nicaragua claimed the US had used armed force and intervened in its affairs contrary to international law. The Court could not consider US ability under the
UN Charter and other multilateral treaties because of a US reservation to its acceptance of the Court's jurisdiction that excluded "disputes arising under a multilateral treaty". Yet,
the court ruled that customary rules on armed force and intervention continued to bind the
US in parallel with the obligations under the UN charter and other multilateral treaties
At 207: "...for a new customary rule to be formed, not only must the acts concerned
"amount to a settled practice", but they must be accompanied by the opinio juris sive necessitatis."
a) State practice i.

What counts as state practice? Omissions are relevant where actions, in particular protests to the actions of other
States, are expected. Such circumstances usually arise where a State violates international law. If other States omit to protests, this can be taken as evidence of acquiescence, which is itself evidence that the acquiescing State regards the activity or state of affairs as consistent with international law. The acquiescing State may be counted as a supporter of the rule in question along with any States whose positive actions have contributed to the 'general practice accepted as law'.
 Anglo-Norwegian Fisheries Case (1951) ICJ Rep 116, at 138, which states that acquiescence cannot be established unless a state has actual or constructive knowledge of the claim being made.
 Navigational and Related Rights (Costa Rica v Nicaragua) (2009) ICJ Rep 213
Facts: Nationals of Costa Rica used to fish on Nicaraguan territory, without the latter's consent. This kind of behaviour calls for protest from Nicaragua, but the latter remained silent on the issue.
Verdict: Nicaragua's silence in these circumstances amounted to acquiescence.
At para 141: "For the Court, the failure of Nicaragua to deny the existence of a right arising from the practice which had continued undisturbed and unquestioned over a very long period, is particularly significant."
Protests are relevant too. In situations where States violate international law, if the other
States protests, this strengthens the existing international rule - in this sense, breaches of CIL
followed by condemnation by other States strengthens the CIL.
International Law Commission considers that the "records of the cumulative practice of international organisations may be regarded as evidence of customary international law with reference to states' relations to the organisations". The International Court also noted that evidence of the existence of rules and principles may be found in resolutions adopted by the
General Assembly and Security Council of the UN.
States' municipal laws may in certain circumstances form the basis of settled practice as well.
 The Scotia case decided by the US Supreme Court in 1871
Facts: British ship sunk American vessel on the high seas.
Verdict: British navigational procedures established by British Parliament formed the basis of international custom since other states had legislated in virtually identical terms.
Hence, in not displaying correct light, American vessel was at fault.
Lowe argues that in reality, State practices are not exhaustively compiled. In fact, one of the following two approaches are adopted: 

ii. (1) There are compilations of digests of State practices. Some States publish annual surveys of their practice on points of international law. For e.g., see the Digests of United
States practice in international law prepared by the State Department.
(2) Ignorance. It is rare for the practice of more than a couple of dozen States to be cited on a point of customary law; and not uncommon for far fewer States to be cited. Of course, on some matters by no means all States will have relevant practice. Afghanistan's practice on the Law of the Sea, for example, is probably sparse. But on other matters practice is widespread. There is in principle no reason for neglecting the practice of any
State; but international law as it is practised is a real-time activity. Practitioners do the best that they can within the time available; but that time rarely permits more than a limited scrutiny of material. This leads to the problem of ignoring States whose languages and cultures are more inaccessible. Indeed, the formulation of CIL in the 20 th century was propounded mostly be Western States.
Need state practice be universal?

North Sea Continental Shelf Cases: (1) the passage of only a short period of time is not necessarily a bar to the formation of CIL, (2) but an indispensable requirement would be that within the period in question, short though it might be, State practice, including that of States whose interests are specially affected, should have been both extensive and virtually uniform in the sense of the provision invoked."
(1) Akehurst: North Sea Continental Shelf cases must be seen in context. There,
acknowledging the equidistance principle as CIL would conflict with pre-existing CIL
on the subject; the amount of practice which is needed to establish a new rule which conflicts with the previously accepted rule is greater than the amount of practice needed to establish a new rule in vacuo
(2) Some commentators emphasise Article 38(1)(b) ICJ Statute: "international custom, as evidence of a general [(not universal)] practice accepted as law".
(3) What about persistent objector principle?
Akehurst: The number of States needed to create a rule of customary law varies according to the amount of practice which conflicts with the rule. A practice followed by a very small number of States can create a rule of customary law if there is no practice which conflicts with the rule. Moreover, the number of States in the world is now much higher than it was in the nineteenth century and the first half of the twentieth century; many of them have been independent for only a short period of time, with the result that their practice on many topics is non-existent or at least unpublished. To require practice by a high proportion of States in these circumstances is to make the establishment of new customary law an intolerably difficult process.

iii. Need state practice be consistent? "Absolute rigorous conformity" is not necessary. "General consistency" suffices.
 Nicaragua v USA
Facts: Nicaragua claimed the US had used armed force and intervened in its affairs contrary to international law. The Court could not consider US liability under the UN
Charter and other multilateral treaties because of a US reservation to its acceptance of the
Court's jurisdiction that excluded "disputes arising under a multilateral treaty".
The question was if CIL regarding armed force and intervention continued to bind the
At para 432: "The Court does not consider that, for a rule to be established as customary,
the corresponding practice must be in absolutely rigorous conformity with the rule. In order to deduce the existence of customary rules, the Court deems it sufficient that the conduct of states should, in general, be consistent with such rules, and that instances of state conduct inconsistent with a given rule should generally have been treated as breaches of that rule, not as indications of the recognition of a new rule."

iv. Is the practice of some States more important than others?

North Sea Continental Shelf Cases: practice must include the practice of states whose interests are specially affected, and that the absence of practice by other States did not prevent the creation of CIL.
Lowe: two examples where some States wield greater influence - space law (especially USA
and USSR), maritime boundaries (coastal States).
But North Sea Continental Shelf cases implied an important limit: absence of contrary practice by other States.
Akehurst: Not invariably true that the practice of more powerful States is more important to creation of CIL than less powerful states.
1) Practice of some States are more frequent and widely publicized than others. For e.g.,
States which have just come into existence likely have little state practice on many matters.
2) Some States are more interested in some matters than others. For e.g., a State with world-wide interests, which maintains embassies in all other States, will have more opportunities to contribute to the development of rules concerning diplomatic immunities than a small State which can afford to maintain embassies only in two or three other States.

v. Persistent objectors
Judicial recognition Few international courts and tribunals have affirmed the doctrine. It has only been considered once in all ICJ decisions. Most importantly, there has never been a court or tribunal which held that a CIL existed but that the doctrine successfully prevented its application to the persistent objector state.
Anglo-Norwegian Fisheries Case. Facts: Norway had adopted its own traditional system of delimitation (the method of 'straight lines') in order to determine the drawing of the baseline for measuring the breadth of the territorial sea or fisheries zone with respect to bays. The
United Kingdom only accepted the legitimacy of that method for 'historical bays'. It argued that another method of delimitation (the 'ten miles rule') had become customary law for all other situations and should, therefore, be applied by Norway. Held: no CIL of ten miles rule.
Obiter: "In any event the 10-mile rule would appear to be inapplicable against Norway inasmuch as she has always opposed any attempt to apply it to the Norwegian coast.'
State practice on the matter
But why is this relevant? The doctrine is not CIL itself, is it?
There is no example of State practice where a State's opposition to a customary rule was recognized by other States and where the claimed special status was effective in preventing the application of that rule to the dissenting State. Of course, there is distinction between existence and enforceability - just because the doctrine is not enforced does not mean it doesn't exist. Dumbarry: but it does mean the doctrine is ineffective and valueless.
For e.g. the overwhelming majority of States never accepted the apartheid regimes of
South Africa and the Republic of Rhodesia. Both countries had timely and continuously objected to the emergence of customary rules prohibiting such racist regimes, but that did not protect them from the ever-increasing pressure from other States to conform to the standards prevailing in international law. Their status as persistent objectors gave them no legal protection against the constant pressure exerted by the international community and the legal, political and economic actions taken by other States. Both countries eventually gave up their dissenting position: Southern Rhodesia became an independent State in 1980
(the Republic of Zimbabwe) and the regime of Apartheid ended in South Africa in 1994.
But during the debates in the GA's Sixth Committee on the ILC's work on the Identification of Customary International Law, States were on the whole positive regarding its existence.


Against Voluntarist theory of international law

Politically convenient

New states

Coheres with the "voluntarist"
theory of international law. The theory assumes that the will of sovereign states is the foundation of international law; states are bound only by laws to which it has itself consented. Lotus case (PCIJ): "The rules of law binding upon states...emanate from their own free will as expressed in conventions or by usages generally accepted as expressing principles of law".

Dumbarry: But if international law is really voluntary, why does persistent objection have to occur during formation of the CIL -
shouldn't it be equally effective after the CIL has been cemented?
Many scholars argue that 'the obligation to conform to rules of international law is not derived from the voluntary decision of a State to accept or reject the binding force of a rule of law'; it is instead 'the societal context which motivates
States to have an international law and obligates them to conform to its norms' (Charney).

Doctrine is necessary to prevent the tyranny of the majority in the multilateral forum
What if after a CIL is formed a new state comes into existence and maintains persistent objection to the
CIL? Many scholars argue that the new state would not be able to opt out (like Akehurst) since that would undermine an already established
But this would contradict the voluntarist theory of international law. Judge Ammoun, in a SO in
North Sea Continental Shelf Cases,
argued that new states should be allowed to determine which CIL they want to accept.
Yet, at the same time, allowing all new States to pick and choose which
CILs they want to opt into would be chaotic (as many scholars suggest).

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