ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel
  • »
  • Education and Science»
  • Law & Legal Issues

Sources of International Law

Updated on May 11, 2013


Bilateral Treaty - A treaty between two parties.

Multilateral Treaty - A treaty between more than two parties.

Universal Treaty - A treaty of all parties.

Pacta sunt servanda - Latin phrase, means that a treaty is binding on parties and must be performed in good faith.

Peremptory Norm/Jus cogens norm - A norm accepted and recognised 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 (art. 53)


The rules of international law come from many different sources. Given the lack of a universal legislative body for the world, the doctrine of sources of law has come into being. A good place to look for a list of possible sources of international law is Article 38 of the International Court of Justice's (ICJ) Statute.1

List of Sources

Article 38 of the ICJ's Statute lists the following sources of international law:

  1. Conventions (e.g. Treaties)
  2. Customary International law
  3. General Principles
  4. Judicial Decisions (e.g. from the ICJ)
  5. Writings of Highly Qualified Publicists (e.g. Academics)



Treaties are now the most important source of international law. They allow States a method by which to create binding international agreements. Examples of important treaties to international law include the Vienna Convention on Diplomatic Relations 1961, and the Law of the Sea Convention 1982. Such treaties can establish global standards for specific areas of activity, e.g. fishing.

Bilateral treaties are when two States enter into an agreement with each other with no third party involvement.
Multilateral treaties, such as the European Convention on State Immunity, may allow more than two States to join, but even these lack universality.

Although most nation-States are absent from the operation of bilateral and multilateral treaties they have proven vital to the international legal system.

Advantages to Treaties

  1. Written, and thus clearer.
  2. Can be made rapidly.
  3. Can be tailored to suit different States (Allow for reservations)

Vienna Convention on the Law of Treaties

Article 6
Every State possesses the capacity to conclude treaties.

Article 7

1. A person is considered as representing a State for the purpose of adopting or authenticating the text of a treaty or for the purpose of expressing the consent of the State to be bound by a treaty if:

(a) he produces appropriate full powers; or

(b) it appears from the practice of the States concerned or from other circumstances that their intention was to consider that person as representing the State for such purposes and to dispense with full powers. …

2. In virtue of their functions and without having to produce full powers, the following are considered as representing their State… (a) Heads of State, Heads of Government and Ministers for Foreign Affairs, for the purpose of performing all acts relating to the conclusion of a treaty….

Article 10

The text of a treaty is established as authentic and definitive:

(a) by such procedure as may be provided for in the text or agreed upon by the States participating in its drawing up; or

(b) failing such procedure, by the signature, signature ad referendum or initialling by the representatives of those States of the text of the treaty or of the Final Act of a conference incorporating the text.

Article 18

A State is obliged to refrain from acts which would defeat the object and purpose of a treaty when:

a)it has signed the treaty or has exchanged instruments constituting the treaty subject to ratification, acceptance or approval, until it shall have made its intention clear not to become a party to the treaty; or

b)it has expressed its consent to be bound by the treaty, pending the entry into force of the treaty and provided that such entry into force is not unduly delayed.

Article 26
Every treaty in force is binding upon the parties to it and must be performed by them in good faith.

Article 34
A treaty does not create either obligations or rights for a third State without its consent.

Article 35

An obligation arises for a third State from a provision of a treaty if the parties to the treaty intend the provision to be the means of establishing the obligation and the third State expressly accepts that obligation in writing.

Definition of a Treaty in the VCLT:
Article 2(1): For the purposes of the present Convention … ‘treaty’ means an international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation.


Art. 2(1)(d) VCLT

Defines a reservation as ‘a unilateral statement, however phrased or named, made by a State, when signing, ratifying, accepting, approving or acceding to a treaty, whereby it purports to exclude or to modify the legal effect of certain provisions of the treaty in their application to that State.

Article 19 VCLT

A State may, when signing, ratifying, accepting, approving or acceding to a treaty, formulate a reservation unless:

a)the reservation is prohibited by the treaty;

b)the treaty provides that only specified reservations, which do not include the reservation in question, may be made; or

c)in cases not failing under subparagraphs (a) and (b), the reservation is incompatible with the object and purpose of the treaty.

Article 23(1) VCLT

A reservation, an express acceptance of a reservation and an objection to a reservation must be formulated in writing and communicated to the contracting States and other States entitled to become parties to the treaty.

Accepting Reservations
No express acceptance is required if the reservation is authorised by the treaty (Art. 20(1)

If it appears from the limited number of negotiating states and the object and purpose of a treaty that the application of the treaty in its entirety is an essential condition all parties must accept a reservation (Art. 20(2))

With a constituent instrument of an international organisation the competent organ of the organisation must approve (Art. 20(3)

20(4) In cases not falling under Art 20(1-3) (unless the treaty provides otherwise)

a)Acceptance by another state of a reservation makes the reserving state party to the treaty in relation to the accepting state

b)Objection to a reservation does not preclude the entry into force of the treaty as betweent he objeting and reserving states unless the objecting state says so

c)Ratification of a reserving state is effective as soon as at least one other state accepts the reservaiton

Reactions to a Reservation

  1. express acceptance
  2. implied acceptance (raised no objection for 12 months; Art. 20(5))
  3. objection
  4. objection where the objecting state definitely expresses a desire that the treaty not enter into force between it and the reserving state

Legal Effects

Reserving state needs at least one state to consent to its reservation for its ratification to be effective (Art. 20(4)(b))

If a ‘major’ objection, no treaty between the objecting and reserving state.

With a state which accepts or makes a ‘minor’ objection, the treaty is modified between it and the reserving state…for both parties (Art. 21(1) and (3).

The reservation does not modify the treaty for the other parties among themselves (Art. 21(2)).

Interpretations of Treaties

There are three main theories on how to interpret treaties:

  1. Intentions of the drafters (often recourse to travaux préparatoires)
  2. Textual (ordinary meaning of the words)
  3. Teleological (aims and objects)

VCLT Article 31

1. A treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose.

2. The context for the purpose of the interpretation of a treaty shall comprise, in addition to the text, including its preamble and annexes:

(a) any agreement relating to the treaty which was made between all the parties in connection with the conclusion of the treaty;

(b) any instrument which was made by one or more parties in connection with the conclusion of the treaty and accepted by the other parties as an instrument related to the treaty.

3. There shall be taken into account, together with the context:

(a) any subsequent agreement between the parties regarding the interpretation of the treaty or the application of its provisions;

(b) any subsequent practice in the application of the treaty which establishes the agreement of the parties regarding its interpretation;

(c) any relevant rules of international law applicable in the relations between the parties.

4. A special meaning shall be given to a term if it is established that the parties so intended.

VCLT Article 32

Recourse may be had to supplementary means of interpretation, including the preparatory work of the treaty and the circumstances of its conclusion, in order to confirm the meaning resulting from the application of article 31, or to determine the meaning when the interpretation according to article 31:

(a) leaves the meaning ambiguous or obscure; or

(b) leads to a result which is manifestly absurd or unreasonable.

Invalidity of Treaties

There are a few reasons why a treaty which meets the formal requirements of creation can be unenforceable. Firstly, is if it breaches Article 47, whereby the representative was subject to a restriction which he or she did not observe. (e.g. they were unable to legally sign the treaty)

Second, is where there has been an error in a part of the treaty's essential basis. (Article 48) However, see the Temple of Preah Vihear (ICJ 1962) Case where it was decided that a party may not claim error if it contributed to the error by its conduct, could have avoided it or was aware of the error.

Third, where there was fraud by another state (art. 49)

Fourth, where a representative was corrupt (art. 50)

Fifth, where there was coercion of a representative (art. 51); see Nicaragua v. Colombia (ICJ 2007) where Nicaragua argued it was coerced due to US occupation.

Waiving the Right to Deem a Treaty Invalid

A state can lose its right to invalidate a treaty if, after it is aware of the facts it:

1. Expressly agrees that the treaty is valid, or remains in force.

2. By its conduct it can be considered as having acquiesced in the treaty’s validity (Art. 45) See the case of Nicaragua v. Colombia (ICJ 2007) again. In this case Nicaragua’s claim that the treaty was the product of coercion came after it had been in force for over 50 years!

When can a Treaty be Void?

When the treaty was concluded on a threat of force. (Art. 52)

If the treaty conflicts with a peremptory norm at the time of its conclusion. (Art. 53)

The treaty can also become void if a new peremptory norm emerges. (art. 64)

Material Breach

In bilateral treaties, the other party can use material breach as a basis for termination. (Art. 60 (1)).

In a multilateral treaty, the material breach of one party entitles the other parties by unanimous agreement to terminate the treaty; OR

A specially affected party to suspend the treaty between itself and the breaching state; OR

Any non-breaching party to suspend if the breach radically changes the position of every party. (Art. 60(2)).

See the case of South West Africa (ICJ 1970) where it was decided that the right of termination may be presumed for all treaties. (except humanitarian treaties)

Other Basis for Treaty Termination

If provided for within the treaty. (Art. 54(a))

At any time with the consent of all parties.(54(b))

Where there is no provision on termination or withdrawal but it is clear the parties wanted that or it can be implied. (art. 56)

A subsequent treaty dealing with the same subject matter is made which was intended to supersede the original or can’t work alongside it. (art. 59)

Supervening impossibility of performance, e.g. due to the permanent disappearance of an indispensable object (art. 61)

Fundamental change of circumstances, which was unforeseen but only if:

1.The circumstances constituted an essential basis of the consent to be bound and

2.The effect is radically to transform the extent of future obligations (art. 62)

See the Fisheries Jurisdiction (ICJ 1973) case where it was decided that the change must ‘have increased the burden of the obligations … to the extent of rendering the performance something essentially different." It was also stated that Art. 62 was customary international law.

Customary International Law

Customary international law is the law which derives from the practices of States. State practice can give rise to customary international law when the practice in question is uniform, consistent and general, and if it is coupled with a belief that the practice is obligatory, rather than habitual (opinio juris). State practice means ANY act or statement by a State from which views about customary law can be inferred. (Including physical acts, claims, declarations in abstracto (e.g. UN General Assembly resolution), national laws, national judgements and omissions.)

Customary law can also be created through the practices of international organisations and (in theory) of individuals.

There is a twofold requirement for customary international law:

  1. It must be a uniform and consistent State practice; and
  2. there must be opinio juris sive necessitatis.(State's belief that the behavior is required by law.)

State Practice

State practice can be found in any of the following:

  • Official Government statements and press reports;
  • National laws, acts or omissions;
  • Statements by officials in diplomatic communications, or at bodies like the UN;
  • Judicial or Administrative decisions;
  • National policy documents.

Opinio Juris

Opinio Juris can be found in the following:

  • Official government statements and communications.

However! These are subjective in nature and it needs to be proven that the government is doing what it is doing because it thinks it is legally obliged to.

Special Customs
Also known as regional customs, these can co-exist with general customary law. There is little difference between the two other than the regional jurisdiction of special customs.

The Persistent Objector

If a State continually objects to an emerging customary rule then it can absolve it from the scope of the rule. This is known as the problem of the 'persistent objector.' A State is not bound by a customary rule if it has consistently opposed the rule from its inception.

However, new States must abide by customary laws which were established prior to their independence.

Stages of Making a Treaty (VNAACE)

  1. Verification of full powers
  2. Negotiation
  3. Adoption of the text
  4. Authentication of the text (usually signature)
  5. Consent to be bound (usually ratification)
  6. Entry into force


•lex posterior derogat priori

•lex specialis derogat generali

•ut res magis valeat quam pereat


The Burden of Proof
As the Court has said on a number of occasions:

The party asserting a fact as a basis of its claim must establish it. (Sovereignty over Pedra Branca/Pulau Batu Puteh, Middle Rocks and South Ledge (Malaysia/Singapore), Judgment of 23 May 2008, para. 45; Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v. Serbia and Montenegro), Judgment of 26 February 2007, para. 204, citing Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Jurisdiction and Admissibility, Judgment, I.C.J. Reports 1984, p. 437, para. 101). (SHORTEN THIS BLOCK OF TEXT)

Ukraine placed particular emphasis on the Court’s dictum in the case concerning Territorial and Maritime Dispute between Nicaragua and Honduras in the Caribbean sea (Nicaragua v. Honduras) that “[t]he establishment of a permanent maritime boundary is a matter of grave importance and agreement is not easily to be presumed” (Judgment of 8 October 2007, para. 253).

Romania/Ukraine, ICJ Judgment, 2009 (READ THIS AND FIX IT UP A BIT!)

Soft Law

Article 10 (UN Charter)

"The General Assembly may discuss any questions or any matters within the scope of the present Charter or relating to the powers and functions of any organs provided for in the present Charter, and, except as provided in Article 12, may make recommendations to the Members of the United Nations or to the Security Council or to both on any such questions or matters..."

An example of soft law is, "The Universal Declaration of Human Rights (1948)"

Vienna Convention on Law of Treaties - Important Points to Remember

Article 38 (VCLT)

Rules in a treaty cannot become binding upon a third state without the third state's consent.

Article 53 (VCLT)

Treaties conflicting with a peremptory norm of general international law (“jus cogens”)

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.

Article 64 (VCLT)

Emergence of a new peremptory norm of general international law (“jus cogens”)

If a new peremptory norm of general international law emerges, any existing treaty which is in conflict with that norm becomes void and terminates.

Important Cases

Qatar v. Bahrain (Jurisdiction) (ICJ 1994)

The case of Qatar v Bahrain concerned whether minutes of a Committee were a treaty. As the VCLT states, treaties can take a number of forms. The court looked to the decision of the Aegean Sea Continental Shelf case of 1978, where they quoted, "the Court must have regard above all to its (the alleged treaty's) actual terms and to the particular circumstances in which it was drawn up." The 1990 Minutes included a reaffirmation of obligations previously entered into. They did not merely give account of the discussions. They enumerated the commitments to which the Parties had consented." Thus, it was decided that the Minutes created rights and obligations in international law for both Parties.

Nuclear Test Cases (ICJ 1974)

Declarations made by the way of unilateral acts concerning legal or factual situations can have the effect of creating legal obligations. Declarations of this kind may be, and often are very specific. When it is the State's intention that it should become legally bound according to its terms that intention confers on the declaration the character of a legal undertaking.

Frontier Dispute Case (ICJ 1986)

Greater caution is called for with unilateral statements.

DRC v Rwanda (ICJ 2002)

Rwanda relied on Article 7(2) of VCLT to say that it was not bound by a statement of its Minister of Justice at the UN Commission on Human Rights. The Minister stated that they would withdraw their reservations to various human rights treaties. The Court noted two things, firstly that she said she was, 'speaking on behalf of the Rwandan people,' and secondly, that the Minister of Justice may bind the State in certain circumstances.

Genocide case (ICJ, 1951) (About Reservations) (REWRITE THIS ONE IN GOOD ENGLISH)

General Assembly may request advisory opinions from the ICJ on legal matters (Art. 96(1) of the Charter) Here the issues were ▫ whether a reserving state to the 1948 Genocide Convention could be regarded as a party to the Convention even if some states have objected whe effect of the reservation with a) parties who object and b) parties who object

It is a well-established principle that states may not be bound without their consent and no reservation can be effective against it without the state’s consent (in the same way that all states must accept positions during negotiations). But ‘a state which has made and maintained a reservation which has been objected to by one or more parties but not others, can be regarded as being a party to the Convention if the reservation is compatible with the object and purpose of the Convention.’

The character of a multilateral convention, its purpose, provisions, mode of preparation and adoption, are factors which must be considered in determining, in the absence of any express provision on the subject, the possibility of making reservations, as well as their validity and effect.’

‘if a party to the Convention objects to a reservation which it considers incompatible with the object and purpose of the Convention, it can…consider that the reserving state is not a party to the Convention’ •‘no state can be bound by a reservation to which it has not consented’ there fore it is up to each objecting state to decide if the reserving state is a party to the convention

Belilos v. Switzerland (ECtHR: 1988) (REWRITE IN GOOD ENGLISH)

The difference between an interpretative declaration and an reservation. Look to the intent of the drafters. If the effect of the statement is to make the party’s consent to the treaty conditional on the acceptance of the content of the declaration, rather than simply offering an interpretation of the treaty, the declaration should be treated as a reservation


1. Statute of the International Court of Justice 1945


    0 of 8192 characters used
    Post Comment

    No comments yet.