Sources of
International Law
Sources of International Law
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Lack of single legislature to create rules of international law
binding upon everyone
Different concepts may be used “sources” + “causes” +
“basis” + “evidence”
We can differentiate between “sources” and “causes”:
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Causes are basic factors that create real rules
can be found in social and historical circumstances of the
international community
These causes can be named as “material sources” (Maddi
Kaynak)
Material sources can be inferred from ideology + economy +
culture + religion
Sources of International Law
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“sources” This refers to a “process” by
which a rule becomes identifiable
These are called as “formal sources” (şekli
kaynaklar) They are the sources from
which the legal rules receive their legal
validity
Formal sources enable rules of law to be
identified and distinguished from other rules
Sources of International Law
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What are the formal sources of international
law?
Practices of states and international
organizations (international courts) show
ussources that are accepted as such
We can find some proofs within Article 38 of
the statute of Permanent Court of
International Justice (PCIJ) and International
Court of Justice (ICJ)
Sources of International Law
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Art. 38 does not state that it contains formal
sources of int law this is usually inferred
This article cannot itself create or provide validity
of sources because it belongs to one of those
sources
This article is legally binding for the ICJ
Sources in this Article they are authoritative
because they reflect state practice
Widely recognized as the most authoritative
statement as to the sources of international law
Article 38 of the Statute of ICJ
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Art. 38: “1. The Court, whose function is to decide in
accordance with international law such disputes as are
submitted to it, shall apply:
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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. “
Article 38 of the Statute of ICJ
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Since all member states to the UN are ipso facto [by the
fact itself/by the very fact]parties to the statute of the ICJ by virtue
of Art. 93 of the Charter This statement can be
seen as “enumeration of sources of international
law”.
Art. 93 of the Charter “All Members of the United Nations
are ipso facto parties to the Statute of the International Court of
Justice. A state which is not a Member of the United Nations may
become a party to the Statute of the International Court of Justice on
conditions to be determined in each case by the General Assembly
upon the recommendation of the Security Council”
Article 38 of the Statute of ICJ
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It seems that there are two categories of sources:
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A- Primary (Basic) Sources
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B- Secondary (Subsidiary/supplementary) Sources
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International treaties
Customary rules of int law
General principles of law
Court decisions
Doctrine (academic writings)
Another categorization:
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A- Law-creating processes first three
B- Law-determining sources last two verification
Sources of international law
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Secondary or law-determining sources
cannot directly create rules of int law
These sources help us to understand
“existence” of rules and their “meaning and
content”.
Whether a rule is established or what the
substance of that rule is
international treaties
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Consensus of consents/concurring wills
Criteria for a document to be seen as a “treaty”
1- International treaties should be concluded by the
actors that are entitled by int law to do this who can
conclude? (states, int org, federated entities etc.,. But not
contracts between states and private persons contract
on license for gas and oil exploitation)
2- It should be concluded in conformity with the rules of
int law and be concluded to achieve legal
consequences applicable law must be int law [Cyprus High
] and “separate legal personalities” of public
corporate bodies
Level Agreements
Criteria for int treaties
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3- This action should create new rights and
obligations or should put an end to the previous
rights and obligations
4- Consensus should occur at least between two or
more int legal personality
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Unilateral legal acts recognition, notification, renunciation
National unilateral acts
Resolutions of int organizations decision making
procedure end-product is the legal action of the
organization
Criteria for int treaties
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5- Written format is not required for an instrument to
be accepted as an international treaty even “oral
consensus” is considered as a treaty
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1975 Agean Continental shelf case (Joint Declaration)
Art 2 (1969 Vienna) “treaty means an international
agreement concluded between states in written form..”
Art. 3 (1969 Vienna) “the fact that the present Convention
does not apply to ... İnternational agreements not in written
form shall not affect the legal force of such agreements”
International treaties  Gentlemen’s Agreements
Non-binding agreements soft law (OSCE)
Customary Rules of International Law
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What is said in Art 38 “international
custom, as evidence of a general practice
accepted as law”
Two Basic Elements in the creation of
customary rule of international law:
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1- Objective element “state-practice”
actual behavior of states/int organizations
2- Subjective element “opinio juris” a
belief that such behavior is law
Customary rules of int law
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Customary rules are not usually written down
or codified but 1947 International Law
Commission “codification”
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Lex lata the law as it is
De lege ferenda progressive development of int
law
Customary Rules State-practice
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What type of legal acts should be taken into
consideration as state-practice?
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Not only external, but also internal acts (legislation + court
decisions + diplomatic correspondence + voting behavior at
int conference, org + treaties + recognition)
Some conditions for an acceptable state practice:
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1- Duration: No rigid time element depend upon
circumstances in certain fields rules have developed
quickly normally it takes time a slow process
2- Continuity and repetition: “does a single act form a
usage/practice?” sometimes yes (“instant customary rule”
which was criticized)
Conditions for valid practice
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3- Consistent and uniform practice:
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“no interruption” in favor of other practice
Must not be uncertain and contradictory
Sufficient uniformity of practice is needed
Some inconsistent conducts should be treated as breach
not a new rule
4- Generality
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Don’t have to be accepted/observed by every state an
extensive practice is needed
If enough practice exist silence is acceptance
But once the rule exists it will be binding for every state
except “persistent objectors”
Customary RulesOpinio juris
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Subjective element why?
Art. 38 ICJ “accepted as law”
To separate int law from principles of morality or
social usage
Distinguish between practice undertaken because of
law from practice undertaken because of series of
other reasons (such as good will & ideological
support)
Opinio juris a belief that a state activity is legally
obligatory
Customary RulesOpinio juris
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State will behave a certain way because they
are convinced it is binding upon them to do
so.
Opinio juris may be deduced from a)
conclusion of bi-lateral and multi-lateral
treaties; b) attitudes during the process of
passing certain resolutions of the UN
General Assembly and other int org; c)
statements by state representatives
Other points about customary rules of
international law
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“Major powers of the field” no need for a
rule to be accepted by every state but
there is a need for such rule to be acceped
by the major powers of that field.
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Influence of the UK on the development of the law
of the sea not practice by “land-locked states”
Impact of Soviet Union and the US on space law
Impact of certain states on law on nuclear
weapons
Other points about customary rules of
international law
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“Local custom in international law”:
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All states from that region must participate
Silence does not mean implied acceptance
Invoking states must prove it
“Persistent objector”:
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If there is a failure to act against a customary rule/a failure
to object this can be seen as an “acquiescence” (tacit
acceptance) this may make customary rule binding for
that state as well.
If a state objects from the very begining of the formation of
that rule + persistently (determined to do so)
General Principles of Law
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In any legal system there may arise cases
where there is no law covering that
point/dispute
In such cases
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A rule may be deduced by analogy from existing
rule
Orit may be deduce from the GPL
General Principles of Law
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Because int law is relatively an
underdeveloped system sometimes there
may exist gaps that cannot be covered by the
rule of int law
But a judge in int law cannot abstain from
taking a decision on a dispute before it on
ground of non-existence of a rule (principle
of non-liquet)
General Principles of Law
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Art. 38 ICJ: “general principles of law recognized by
civilized nations”
They are inherent in any legal system
Reference in Art. 38 is made to GPL in municipal
systemsin so far as they are applicable
But if rules of conventional or customary int law are
sufficient to supply necessary basis for decisionno
need
They have a lower position in the hierarchy of laws
But they are not listed as subsidiary means under
Art. 38
General Principles of Law
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They are common principles to different legal
systems:
Examples:
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PCIJ 1928 Chorzow Factory Case “every
violation of an undertaking involves an
obligation to make reparation”
Even if there is no such provision within a treaty a
court may attribute responsibility to a wrongdoer
state because this is a GPL
General Principles of Law
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Estoppel principle:
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If a state consents impliedly (acquiescence) to a
specific situation or an act it shall lose its right
to object to that situation in future
1962 Temple Case
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between Cambodia and Thailand ICJ awarded the
ownership to Cambodia
A flag raised a visit paid by an official
Preah Vihear Temple
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Preah Vihear Temple
Estoppel
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One side engaged in such acts of sovereignty as "...the building
of roads to the foot of Mount Preah Vihear, the collection of
taxes by Siamese revenue officers on the rice fields of Mount
Preah Vihear, the grant of permits to cut timber in the area, the
visits and inspections by Siamese forestry officers, the taking of
an official inventory in 1931 of ancient monuments which
included the Temple of Preah Vihear, the visit of the UnderSecretary of the Ministry of the Interior in 1924-25 and the visit
of Prince Damrong in 1930, both visits including the Temple of
Preah Vihear." At no times did the French Government lodge
any protest against these activities.
Words matter
Other GPL
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Pacta sunt servanda
Ex injuria ius non-oritur  one cannot benefit
of its own wrongful conduct (expCyprnecessity)
Secondary/subsidiary sources of
international law
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1- Judicial decisions (jurisprudence) (içtihat)
2- Legal/doctrinal writings (Doctrine) (Öğreti)
Judicial Decisions
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Decisions of int courts
Decisions of domestic courts
Arbitral awards
According to Art. 38 subsidiary means for “the
determination of legal rules”
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Determine the existence of legal rules
Determine the substance/meaning of rules
Judicial Decisions
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Reference to Art. 59: Decisions of ICJ;
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Have no binding force for other cases (only for that
particular case)
Have no binding force for other parties (only binding
between the parties)
But ICJ generally prefers a kind of “rule of
precedence”
These sources cannot directly create rules of
international law; but:
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A- Formation of customary rules of int law
B- Act of interpretation is a process of rule-making
Legal/doctrinal writings
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Cannot create rules of int law directly
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All international courts refer doctrine in support of their
positions/decisions/analysis
Writings interpret the rules + suggest modifications +
suggest special provisions in treaties
This has an indirect effect in the formulation of rules of
international law
It includes books, articles, reports (ECHR),
“separate opinions” + “dissenting opinions” of
judges of inter courts.
Issue of Jus Cogens/Peremptrory
Norms of International Law
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1969 Vienna Convention on the Law of Treaties, Art. 53:
“A treaty is void if, at the time of its conclusion, it conflicts with a
peremptory norm of general international law. For the purposes
of the present Convention, a peremptory norm of general
international law is a norm accepted and recognized by the
international community of States as a whole as a norm from
which no derogation is permitted and which can be modified
only by a subsequent norm of general international law having
the same character.”
Hierachy of norms
Lack of international court decisions
Discussion is still continuing