Law of Treaty



Treaty is defined as

“Agreements of a contractual character between states or organizations of states creating legal rights and obligations”.


“In nearly all the cases, the object of the treaty is to impose binding obligations on the states who are parties to it”.


Elements of the Definitions:-

  1. Treaties should be in writing. Oral treaties have no legal status.
  2. Parties to the treaty may be either states, or a state and international organization, or international organizations.
  3. The purpose of the treaty is to create a relationship between the parties.
  4. A treaty should operate within the sphere of international law.

The Vienna Convention on Law of Treaties.

Treaties acquired a prominent place in international relations long before the modern sense of international law came to existence. The customary rules of international law relating to treaties, gradually acquired considerable certainty and precision.

In view of the significations of the law of treaties, the international law commission decided in 1949 to attempt its codification. By 1966, the commission completed its work. On March 23rd, 1969, the UN conference on the law of Treaties adopted the Vienna convention on the law of treaties.

Classification of Treaties:

  1. Bilateral treaties:

Those treaties in which rights and obligations arising from the treaty is limited only to two parties. They are sometimes referred as treaty-Contract.

  1. Pluri-lateral Treaties:-

Those treaties when the participation is open to a restricted number of states. The minimum number of parties in such treaties must be more than two. The purpose of the plurilateral treaty may be either to maintain peace and security or promote and develop the commerce and socio-economic benefits in favour of only a group of states. The regional arrangements as envisaged under Article 52 of the charter of UN are included under this category.



  1. Multilateral Treaties:-

Those treaties which are open to all states without any restriction. They law down general norms of international law and said to perform the functions of International Legislation.

Multilateral treaties are sometimes described as law making treaties. The non-signatory states have no obligations against the treaty. The Vienna conventions has classified treaties into two kinds; bilateral and multilateral. Plurilateral treaties have been made the part of multilateral treaties. Many jurists question this arrangement.

Party to a Treaty:-

Generally, only sovereign states are competent to make a treaty. Those states which are not completely sovereign are not competent to make treaties. Mostly the representatives of the sovereign states first sign treaties but the treaties are not binding to the government or state until they ratify it. Furthermore, international organizations are also entitled to be parties to treaties under a separate convention on law of treaties adopted on March 20, 1986 by the UN General Assembly.

Formation of A Treaty:-

Following are the main steps in the formation of treaties.

Accrediting of Persons On Behalf of Contracting Parties:

The first step in the formation of treaty is the accrediting of persons on behalf of the contracting parties. States authorize some representatives to represent them for the negotiation, adoption on and signature etc of a treaty. Unless those representatives are accredited or authorized, they cannot participate I the negotiations or conclude treaties.


Foreign ministers of P5 +1 (Germany) and Iran in finalizing Iran Nuclear Deal.


The accredited persons of all contracting states proceed for negotiation. While negotiating a treaty, the representatives may consult their government.


When states have negotiated a treaty, they settle its form and content by drawing up a text setting out its provisions. In expressing their agreement this text, states are called to adopt the text. In bilateral treaties, it is just a formality but for treaties involving multiple parties adoption gains significance and requires minimum two-third support of the members. In other treaties, the adoption of the text takes place by the consent of all the participating states.


After negotiation, next important step is signature of the accredited representative of the contracting parties at one place and same time, in the presence of all parties. Signature has no value if the treaty is subjected to notification by the government, except agreeing to the points of the treaty. If the treaty does require ratification from the respected governments of the parties, the treaty becomes active soon after the signature.


When as treaty is signed by the representative of the state, it is confirmed by the state through ratification, which might or might not be a provision of the treaty. The mode of ratification is different from state to state. For example in USA, a treaty is ratified by the President on the advice of the senate. Similarly, in UK, ratification is done by the crown on the advice of minister concerned. The ratification is either forever and can be done even after years or in accordance with the limit prescribed in the treaty.

Purpose of ratification:
  1. Ratification gives an opportunity to the contracting parties to re-examine or review the treaty signed by their representatives.
  2. If a state wants to withdraw from the treaty, it may do it by not ratifying it.
  • A state may need to annual its municipal laws to give an effect to the provisions of the treaty the period between signature and ratification may be utilized in doing so.
  1. The principle of honour of public opinion is expressed over the treaty through parliament, referendum or any other forums.

Accession and Adhesion:

Accession or adhesion is a traditional method by which a state may, in certain circumstances, become a party to a treaty of which it is not a signatory. The right to accede either requires provision of a treaty, or in absence of that, consent of all the states. When a state becomes a party through accessions, ratification is not required. The act of accession is therefore, includes signature as well as ratification.

Normally, accession is open only in multilateral treaties.

Entry Into Force:-

A treaty enters into force in accordance with the provisions of a treaty. Modes of treaties entry to force are

  1. Bilateral treaties enter into the force when both the parties have exchange documents of ratification.
  2. A treaty comes into force with the signature of the representatives where ratification is not required.
  3. Multilateral treaties enter into force from the date when the prescribed numbers of ratifications or accessions have been made.
  4. Some treaties pre-decide a time for itself to enter into force. For instance, the Vienna convention provides under Article 84(1) that the convention shall enter into force on the 13th day following the date of receipt of the 35th instrument of ratification or accession.
  5. A treaty may also enter into force provisionally and can be terminated on the request of state or for not fulfilling conditions.

Registration and publication:-

A treaty is required to be registered with the secretary General of the UN, after it has come into force. The secretariat will publish the treaty, serving two purposes; prevents the state to conduct secret treaties and makes the parties difficult to violate the provisions of the treaty. A non-registered treaty is as much valid as a registered treaty. However, if a treaty is not registered, Article 102(2) of the UN Charter provides that no party can invoke that treaty before any organ of the UN, like ICJ.

Principles of Treaties:

Pacta Sunt Servanda:-

According to this principles, “states are bound to fulfill in good faith the obligations assumed by them under treaties”.

“All members in order to ensure to all of them the rights and benefits resulting from membership, shall fulfill in good faith the obligations assumed by them in accordance with the present charter”.

Article 2, paragraph 2 of Charter of.

“the principle of good faith is one of the basic principles governing the creation and performance of legal obligations”.

Pacta Tertiis Nec Nocent Nec Prosunt:

It is a general principle of treaties that only parties to a contract are bound by the contract or a treaty is binding only to the contracting parties. In other words, this Latin Maxim stipulates that rights and obligations arising from a treaty are binding only to the parties to a treaty and not to a third state without its consent.

“A treaty does not create obligation or right of a third state without its consent”.

            Article 34, Vienna Convention of Treaties:

However, this principle is subject to the following exception.

  1. Under Article 36 of the Vienna convention, Treaties which concern the rights of the third party can be conferred some obligation under the treaty.
  2. Multilateral treaties, on the basis of customary International law, may bind even non-parties.
  3. Multilateral treaties which create new rules of International law may bind non-parties.
  4. When a treaty imposes some obligation on a third party and third state party accepts that obligation, then such a non-party becomes bound by that treaty.

Jus Cogens;-

There are certain principles International Law which all the states must observe and their violation may affect the foundation of the legal system to which they belong. They, therefore, cannot be altered by concluding treaties. These rules possess the character of jus cogen

“a treaty is void if it conflict, at the time of its conclusion, with a peremptory norm of general international law”.

                                    Article 53, Vienna Convention.

                                    “if a new peremptory norm of general international law emerges, any existing treaty which is in conflict with that norm, becomes void.”

Article 24, Vienna Convention.

According to Verdross, three types of jus cogent rules exist in International law.

  1. Those which are in the common interest of the whole international community;
  2. Those created for humanitarian purposes.
  3. Those introduced by the charter of the United Nations against the use of force in the international relations.

The rules of jus cogens exist in International law but they are not well defined as far as it contents are concerned. Jus cogens varies from state to state. For some, sovereignty may be jus cogens. For developing countries unequal treaties may be jus cogens and for other, economic exploitation by developed countries may be jus cogens. This difference is because of the fact that they are necessarily changeable like any other group of rules.

Rebus Sic Stantibus:-

The maxim means that if the fundamental or material circumstances under which a treaty is concluded change, then this change becomes a basis for change or termination of a treaty. 

Termination of Treaties:-

When a treaty comes to an end it is regarded as termination of a treaty. The mode of termination is different for different kinds of treaties. In case of a bilateral treaty, defection of one party can terminate the treaty unlike multilateral treaty where defection of one or small number of parties does not terminate treaty.

Modes of termination of treaty:-

By consent of the parties:-

A treaty may be terminated at any time by the consent of the contracting parties.

By Denunciation:-

In treaties where expression of specific timeframe or event is not given, a treaty may be terminated by denunciation in accordance with Article 5 of the Vienna Convention.

By Concluding Another Treaty:

A treaty shall be considered as terminated if all the parties to it conclude a later treaty relating to the same subject matter and parties intended that the matter should be governed by the subsequent treaty. Moreover, the contents of the later treaty shall be contradictory or incompatible with those of the earlier one and the two treaties are not capable of being applied at the same time.

By Material Breach:-

A material breach or breach of an essential provision of a treaty does not ipso facto put an end to the treaty, but only entitles the other party to invoke the breach as a ground for terminating the treaty or suspending its operations. It also entitles the other party to abrogate the treaty if, despite knowledge of the breach, the aggrieved party chooses to continue operations of the treaty, then it would lose its right to invoke the breach.

Impossibility of Performance:-

A treaty may stand terminated if the events or development make the performance of the treaty impossible.


  • Permanent destruction or disappearance of a party in case succession does not take place.
  • Permanent impossibility of amelioration in situation.
  • A joint project on an island which disappeared or get destroyed in a catastrophe etc.
According to provisions of the Treaty:

A treaty may be terminated in conformity with the provisions and elements of the treaty, time frame, achievement of the good, fulfillment of the object, failure in honouring responsibilities etc.

By Emergence of Jus Cogens:-

A treaty may be abrogated if a new Jus Cogen appear and the treaty is in conflict with that norm.

By Fundamental Change of Circumstances:-       

The factor principle of rebus sic stantibus may also be responsible to terminate a treaty.

Invalidity of Treaties:

A Treaty concluded by the parties may on various grounds subsequently be declared invalid by a competent authority. Following are few grounds of invalidity of a treaty, given in Articles 46-53 of the Vienna Convention:

Lack of proper Authority of the representatives:

If the representative lacked or purged of authority to sign and negotiate the treaty, the treaty is said to be invalid. This is specially the case where a treaty enters into force with just the signature of the representative and does not require ratification.


A treaty may be invalidated of there is an error in the treaty, in accordance with Article 48 of the Vienna Convention. A State may invoke an error in a treaty as invalidity if the error relates to a fact or situation which was assumed by that state to exist when the treaty was concluded. For example, if a boundary treaty is concluded on the basis of a incorrect map, it may become invalid subsequently as the error is factual. However, an error relating only to the wording of the text of a treaty does not affect its validity.


If a contracting party has been induced to conclude a treaty by fraud committed by another, the treaty because invalid.

Corruption of the representative:-

A treaty becomes invalid if the consent of a state has been obtained through the corruption of its representative, directly or indirectly by another party. It may include kickbacks, commissions in dealings substantial undue influence on the representative.

Coercion of a representative:

If the representative of a state has been coerced for giving his consent through acts or threats to mold/influence his decision, the treaty would become invalid.

Coercion of a State:

A treaty shall become invalid if its conclusion has been procured by the threat or use of force against a state, in violation of the International laws of Treaty. This does not include political or economic means of coercion as it would be difficult to distinguish between the legitimate and illegitimate use of such forms of pressures as a mean of securing consent to treaties.

Jus Cogens:-

A treaty shall be invalid if it conflicts with the general principles of International law.

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