Law of Treaties in International Law

International law


The International Court of Justice recognized treaties and conventions, customs, general principles of law and judicial precedents and teachings as the four main sources of international law under Article 38(1). Treaties qualify as the primary source of ascertaining international law. The purposive intention f treaties are to bind states to each other in their trans boundary responsibilities. This helps in fostering friendly relations and even in the defining of the powers, regulatory provisions and formation of international organisations. Treaties have been in play across states from time immemorial, although in the past, a mere oral oath taken in a ceremony would suffice where the parties would swear in the name of God to bind themselves to each other. Written treaties bind the parties legally in the present day.

The law of treaties is governed primarily by the Vienna Convention on the Law of Treaties which was brought to force on the 27th day of January, 1980. This document was legislated by the International Law Commission of the UN for setting up guidelines on the manner of operation of treaties. Majority of the member states of the United Nations have become a party to this Convention.

  • Concept of Treaty

Article 2(1)(a) of the Vienna Convention defines treaty as “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.”. Hence, treaties are essentially agreements entered into through writing between parties to agree to a set of principles regarding any matter which affects internationally. These are referred to as pacts and charters too. Mere statements, declarations and stances made do not qualify as a treaty.

Treaties may be classified on basis of their objects, purpose or number of parties. There may be political treaties defining a party’s allies or disarmament policies, administrative treaties with the purpose of establishing and defining the functions of international organisations, for example, the World Health Organisation. Commercial treaties regarding trade agreements such as the such as the GATT, criminal treaties, human rights treaties, treaties which even codify international law, and civil treaties are some of the classifications based on the object.

Generally, unless a country ratifies a treaty or becomes a signatory, there is no legal obligation of abiding by the treaty terms. This concept has been referred to by the Latin maxim, “pacta sunt servanda” which states that every signatory is bound to follow the treaty obligations in good faith. Pacta sunt servanda forms the basis of treaty law which is recognised under Article 26 of the Convention. The exception to this was laid down in the North Sea Continental Shelf Cases[1] where the ICJ held that certain treaties have a fundamentally norm-creating character. This essentially means that treaties define such conduct, often pertaining to human rights, which binds states internationally.

While signatories are bound by all terms and provisions of the treaty, reservations may be made, through which a signatory absolves itself from obligation of following certain specific provision/s. A reservation against primary clauses which defeat the entire object of the treaty cannot be made. Article 2(1)(d) defines reservations. The primary reasons for which the provision of reservations is made are:

● To encourage states to become parties to the Convention

● To increase the number of ratifications

● Reservations are provided basically because of the various differences that exist between states.

● As a principle to uphold of Sovereignty.

● To avoid conflict with domestic laws.

Role of treaties in International Law

Treaties are the essential source of international law. They are quintessential for establishing diplomacy among member states and laying down ground rules of conduct. They foster international peace, security and cooperation. The importance of treaties is also ascertainable through the Preamble of the Vienna Convention of Law of Treaties by vesting the guarantee of international order as the function of treaties.

Kinds of treaty

Law Making treaties

Law making treating create a binding legislation towards the parties. The sucject matter and content of such a treaty is statutory and not a mere contract. Matters which affect states internationally and require immediate laws to commonly bind the parties and address such an issue by imposing international legal orders led to formation of law making treaties. Law making treaties differ from others as they do not formulate mere rules left to the discretion of the signatories. It creates mandatory obligations in the form of a statute. Hence, the obligations defined by these treaties are independent without the need for a separate set of rules to be followed. Another point of difference is that, law making treaties can set up international tribunals, international mandates, international waterways etc.

Often these treaties are multilateral (more than two parties involved) and ave a common object which affects globally. Human rights treaties and maritime laws are classified as the most common law making treaties by Fitzmaurice.[2] The nature of such a treaty is multilateral in the sense that, there are several bilateral treaties whereby each party is bound to the rest independently and collectively. Therefore, the obligations defined are mandatory. Bilateral treaties are mutually dependent on the existence and terms defined by two parties. Law making treaties are bilateral of the kind which binds the parties to a common cause which is distinct from the personal interests but in favour of a common interest.

Contractual treaties

Unlike law-making treaties, contractual treaties have a more exclusive group of parties, and are often bilateral in nature. There exists a mutual interest from one another between the parties, usually of a commercial or political kind. It is either to gain some kind of benefit or protection in exchange to provide the same in return. While law making treaties are focused on rights, duties, code of conduct and are governed by principles of natural law, morality etc., contractual treaties are focused on one matter of relevance solely to the interested parties and not globally. These are often trade agreements, alliance agreements, conveyance agreements etc. It is almost a pure contract, governed by principles of barter and absolves the rest of the parties from any obligation if one of them fails to upkeep their side of the agreement. This is unlike law making treaties which do not absolve such rights irrespective of a breach from one party but rather imposes penalties on the offending party. 

The Binding Force of Treaties

The Vienna Convention on the Law of Treaties is an international agreement between the states to govern and regulate treaties. The Convention on law of treaties deals with written treaties exclusively. Composed of eighty five articles, the first part of the Convention deals with the basics such as object and scope. The second part of the Convention addresses adoption, ratification and conclusion of treaties. The third part focuses on interpreting treaties. Modifications, amendments and changes to treaties is dealt with in the fourth part, and the termination, invalidity, suspension clauses are elaborated in the fifth part. According to the Convention the International Court of Justice has jurisdiction over all matters of disputes. Technical issues such as the implication of a change in government on treaties and ratification are dealt with in the final parts.

The maxim “pacta sunt servanda” binds all signatories to their treaties and is incorporated under Article 26 of the Convention. Therefore, all signatories of the Vienna Convention are by extension bound to any other treaty they become a signatory to. It is interesting to note that the United States has not ratifies the Convention. This is probably because of differences between the Legislative and Executive branches.  

Article 1 of the said Convention lays out its applicability to treaties between the states. It is also applicable to treaties entered into by international organizations. Article 2 defines “ratification”, “approval”, “reservation”, etc., in the context of the treaty. However, the Convention is not applicable between two subjects of international law or to agreements formed between an international body and a state. Article 3 provides for the scope of the Convention and confirms that even if such agreements are entered into, their legalities shall remain unaffected. However, such parties are not obligated to follow the provisions of the Convention, but must generally conform to the basic principles of international law while forming their treaty provisions.  Further, such agreements do not affect the interaction between states.  

Parties to a treaty

There are two types of parties to a treaty- state parties and third States. State parties are actual signatories of the treaty which have signed, ratified and adopted such treaty. They are bound by it unconditionally. “Third state” is not an actual signatory or party of the treaty.

Third States

Article 34 of the Convention absolves all obligations of a treaty to a third state as it is not a signatory. Further, any provision of a treaty between two states which tends to impose liabilities on a third state cannot be incorporated unless the consent of the third state has been taken. If the third state gives its consent, and the parties wish to vest certain rights to such a state, provisions for the same are allowed according to Article 36 of the Law of Treaties. Only when the third state follows all the conditions and duties imposed on it can it exercise such rights vested in it. The revocation, amendment of the provisions related to a third state are dealt with in Article 37. Article 35 states that when there has been express consent of the parties to the treaty and the third state such a revocation or amendment can take place. However, the rights conferred by Article 36 cannot be revoked or altered without the consent of the third state if it was so provided that such revocation or alteration cannot be done solely by the parties. Further, customary international law provides that the provisions of a treaty become binding on third states too.

Formation of a treaty

There is no set procedure to be followed in the creation of a treaty. However, every treaty must have a Preamble which gives the background object of the treaty, followed by the subject matter of the treat. The time period for which the treaty is formulated, the reservations, ratification, amendment procedures must be laid out. Finally, the ratification and signatures of parties are incorporated. The steps primarily involved in the formation of a treaty are as follows:

Adoption: Unconditional consent except in form of reservations is essential for adoption of the text of a treaty. If the adoption is required internationally, at least two thirds majority is required for adoption.

Authentication: According to the procedures laid down in the treaty itself, the text is made authentic. If no such procedure is provided, the signatures of the parties may be deemed to be a reflection of the authenticity.

Consent is expressed: Consent is expressed through signatures, ratification, acceptance, approval or accession or by exchanging instruments required for the treaty.

  • Consent by signature

The representatives of the states sign the treaty text when signature is enough to imply consent according to the treaty. 

  • Consent by exchange of instruments required by the treaty

Instruments which are equivalent to expression of consent may be exchanged among parties.

  • Consent by ratification, acceptance or approval

Ratification is a reflection of acceptance or approval.

  • Consent expressed by accession

The difference between ratification and accession is that, ratification primarily occurs until the minimum number of signatories required to give force to the treaty. All parties who sign the treaty after the minimum number is achieved are parties by way of accession.

  • Formulation of reservations

While becoming a signatory, a party may provide reservations, if any.

Invalidity of treaty

Part V, Section 2 of the Vienna Convention on The Law of Treaties, 1969, deals with the invalidity of treaties. Articles 46-53 provides for the procedure to be followed for invalidating a treaty. Invalidity essentially means to make a treaty void. Content, the parties and the implications of the treaty are a few reasons to invalidate it i.e., if it becomes impossible, or the issue at hand is already addressed, or by consent of the parties.

Under Article 46 of the Law of Treaties, if the provisions of a treaty goes against its domestic laws, the state may communicate its unwillingness and the desire to invalidate the treaty.

Article 48 allows for invalidation if the treaty has an error which substantially affects the treaty provisions so as to be in conflict with the object of the treaty.

Treaties may be called for invalidation if its consent has been obtained by the fraudulent acts of a party member, or by corruption of its legal representatives, or if such representatives have been coerced on basis on lack of free consent.

Jus cogens are “peremptory norm of general international law” such as piracy, genocide, apartheid, torture etc. If a treaty is in contravention of any of these laws, it can be rendered invalid.

Termination of treaty 

Termination by means of Withdrawal

International law is based on the foundation of consent of the parties. It is in respect of this that treaties have provisions for withdrawal. If the number of signatories falls below the prescribed number due to withdrawal, a treaty stands terminated. Article 56 deals with withdrawal of treaties which do not have termination or withdrawal clause. However, certain treaties do not allow for withdrawal owing to their nature. It is for this reason that North Korea was denied withdrawal from the International Covenant on Civil and Political Rights.                    

Suspension and Termination

  • Implied by the conclusion of a later treaty- 

If a new treaty has been drafted dealing with the same subject matter as a previous one, then upon the conclusion and ratification of the new treaty, the old one is deemed to be suspended.

  • As a consequence of its breach- 

Usually among bilateral treaties, if one party commits a breach of the provisions then the entire treaty can be terminated or suspended at the discretion of the other parties.

  • Impossibility of performance-

When the carrying out of the provisions becomes impossible for any reason, then the treaty can be terminated. If the impossibility if for a specific duration of time, then the treaty may be suspended for that time period.

  • Fundamental change of circumstances

This is akin to force majeure clauses, where due to unforeseen, uncontrolled events, the provisions of the treaty can only be carried out with great impediment.

  • Changes in diplomatic or consular relations

Hostile elations and change in diplomatic relations by themselves cannot lead to suspension or termination unless the treaty specifically provides for such a clause.

  • New jus cogens

Jus cogens are internationally recognized principles. If there exists new jus cogens, then the treaties which are in violation of such a new jus cogen may be terminated.


The Vienna Convention on the Law of Treaties is the principal piece of international document which provides the basics of all other treaties. Pacta sunt servanda is the principal maxim which governs it and enforces obligations on signatories of all treaties. This Convention which provides basis of formation, ratification, amendment, and termination of treaties is of primary importance as treaties form the most fundamental source of international law.

[1] North Sea Continental Shelf, Germany v. Denmark, Order, [1968] ICJ Rep 9.

Author: Shubham Shukla (Christ University)

Law Library LawBhoomi

Leave a Reply