Theorem Case Context/remarks (if any)
Sources of international law
The Court here identified the
potentially contradictory
“Instances of State conduct character of inconsistent
inconsistent with a given rule should conduct which can be evidence
generally have been treated as that a new rule is emerging or
breaches of that rule, not as indication Nicaragua simply a breach of the existing
of the recognition of a new rule.” rule. The key is the manner in
(‘non-compliance does not necessarily which the inconsistent conduct
mean the rule does not exist’) is justified by the acting State,
and whether it is accepted or
rejected by other States.
“Not only must the acts concerned
The Court made some
amount to a settled practice, but they
canonical statements with
must also be such, or be carried out in
respect to custom, and which
such a way, as to be evidence of a
acts are relevant in assessing
belief that this practice is rendered North Sea continental
the existence of a customary
obligatory by the existence of a rule of shelf
rule. ‘States concerned must
law requiring it. The need for such a
feel that they are conforming
belief, ie the existence of a subjective
to what amounts to a legal
element, is implicit in the very notion
obligations.’
of the opinio juris sice necessitatis.
“Reliance by a State on a novel right or When faced with the question
an unprecedented exception to the of how to determine whether
principle might, if shared in principle there existed a customary
Nicaragua
by other States, tend towards a international law prohibition
modification of customary on the use of force, the court
international law.” answered this.
“A party which relies on a regional
local/particular custom must prove
that this custom is established in such Asylum judgement
a manner that it has become binding
on the other party”
What a State does is lawful, unless a
Case of the SS Lotus
rule says otherwise.
“The court sees no reason why long
continued practice between two
States accepted by them as regulating ICJ agreeing on the existence
Right of passage
their relations should not form the of bilateral custom
basis of mutual rights and obligations
between the States.”
Certain German
“A treaty only creates law as between
interests in Polish Codified in VCLT
the States which are parties to it.”
upper Silesia
The Court accepted that a provision of North Sea continental The court had to consider
a treaty can lead to the creation of shelf whether West-Germany was
new customary rules, if the provision bound by certain provisions of
was ‘of fundamentally norm-creating the 1958 convention on the
character’, and thus capable of continental shelf, which it had
forming the basis of an emergent or signed but not ratified, and
,pre-existing customary law. thus was not bound.
“Even if a treaty norm and a
customary norm relevant to the
present dispute were to have exactly The ICJ rejected the idea that
the same content, this would not be a existing custom would be
reason for the Court to hold that the Nicaragua superseded or absorbed into a
incorporation of the customary norm new treaty covering the same
into treaty law must deprive the ground as a customary rule.
customary norm as to its applicability
as distinct from the treaty norm.”
“Opinio juris may, with all due caution,
The ICJ about how opinio juris
be deduced from the attitude of the
can be deduced from
parties and the attitude of States Nicaragua
behaviour of States in the
towards certain General Assembly
general assembly of the UN.
resolutions”
Custom binds States as a legal
obligation without requiring their Gulf of Maine This is known as ‘tacit consent’.
express consent.
, Hierarchy of norms in international law
“Certain obligations of a State toward
the international community as a
whole are the concern of all States. In The first acknowledgement of
Barcelona traction heat,
view of the importance of the rights the ICJ of obligations erga
light and power co
involved all Sates can be held to have omnes.
a legal interest in their protection;
they are obligations erga omnes.”
“All States parties to the convention
against torture, including Belgium,
have a legal interest in ensuring First time that the ICJ applied
Obligation to prosecute
compliance with obligations contained the concept of obligations erga
or extradite
in the Convention, these were omnes in a concrete dispute.
characterized as ‘obligations erga
omnes partes’”
Recognizing the erga omnes character
of the right to self-determination by
East-Timor
the ICJ. However, it is not a norm of
jus cogens!
“In view of the character and the
importance of the rights and
obligations involved”, the Court
declared that all other States were Here the ICJ recognized the
Construction of a wall
under an obligation not to recognize obligation of non-recognition
in occupied Palestinian
the unlawful situation resulting from of breaches of norms of jus
territory
the construction of the wall, as well as cogens.
under an obligations not to render aid
or assistance in maintaining the
resulting situation.”
“The mere fact that rights and
obligations erga omnes or peremptory
norms of general international law (jus A claim of a breach of a rule of
cogens) are at issue in a dispute Armed activities in the jus cogens does not go so far
cannot in itself constitute an exception territory of the Congo as to confer jurisdiction to the
to the principle that its jurisdiction ICJ or any other forum.
always depends on the consent of
parties.”
