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Definition and Types of Treaties



Definition of Treaty (Vienna Convention on the Law of Treaties, 1969)

The primary source for the modern definition and rules governing treaties is the Vienna Convention on the Law of Treaties (VCLT), adopted in 1969. The VCLT is often called the "treaty on treaties" as it codifies the customary international law and principles that apply to agreements between states. While India has signed the VCLT, it has not ratified it. However, India's courts and government consider many of its provisions as reflecting customary international law and therefore binding.

Article 2(1)(a) of the VCLT provides the authoritative definition of a treaty for the purposes of the Convention:

"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."

This definition can be broken down into several key components.


International agreement

This element signifies a meeting of minds or a convergence of will between the parties. The states involved must have a genuine intention to create legally binding rights and obligations among themselves under international law. This distinguishes a treaty from a mere political declaration or a non-binding instrument like a Memorandum of Understanding (MoU) or a joint communiqué, which may only express common goals or intentions without creating legal duties.


Concluded between States

The 1969 VCLT specifically applies to treaties concluded between States. States are the primary subjects of international law and possess full treaty-making capacity. Agreements between a State and an international organization, or between two international organizations, are also treaties in a broader sense but are governed by a separate convention, the 1986 Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations. Agreements between a state and a private foreign company are not treaties but are considered international contracts, typically governed by a specified national law.


In written form

The VCLT applies exclusively to agreements that are in written form. This requirement ensures clarity, precision, and verifiability of the terms agreed upon. While customary international law recognizes that oral agreements between states can be legally binding, such agreements fall outside the scope of the VCLT. The convention does not deny the legal force of oral agreements but simply states that its own rules do not apply to them.


Governed by International Law

This is a crucial element reflecting the intent of the parties. For an agreement to be a treaty, the states involved must intend for it to be subject to the rules and principles of international law, rather than the domestic law of one of the parties. This intent is what gives the agreement its international legal character. The name or designation given to the instrument—be it a 'Convention', 'Pact', 'Covenant', 'Charter', 'Statute', 'Protocol', or 'Agreement'—is immaterial. What matters is the substance of the agreement and the intention of the parties to be bound by it under international law.



Types of Treaties

Treaties are the most important source of international law and can be classified in several ways based on their parties, subject matter, and function. Understanding these classifications helps to appreciate their different roles in the international legal system.


Bilateral vs. Multilateral

This is the most common classification, based on the number of parties to the treaty.


Law-making treaties

Law-making treaties, also known as normative treaties, are treaties that create general norms and principles of conduct that are intended to govern the behaviour of parties for the future. They are analogous to legislation in a domestic legal system.


Treaties creating international organizations

This is a special category of multilateral treaty, often referred to as a constituent treaty or a charter. The primary purpose of such a treaty is to establish a new international organization and to serve as its constitution.



Conclusion and Entry into Force of Treaties



Process of Treaty-Making

The creation of a treaty, from initial idea to legally binding instrument, is a formal and deliberate process governed by both international law (primarily the Vienna Convention on the Law of Treaties, 1969) and the domestic constitutional law of each participating state. While the specific procedures can vary, the process generally follows a sequence of distinct steps: negotiation, authentication of the text, and the expression of consent to be bound (e.g., through ratification).


Negotiation

This is the foundational stage where the representatives of two or more states come together to discuss, draft, and agree upon the content, terms, and wording of a proposed treaty. The nature of negotiations can differ significantly:

Representation of States

A state is represented in negotiations by individuals who possess "full powers," which is a formal document issued by a state's competent authority authorizing a person to represent the state for negotiating and concluding a treaty. However, under Article 7 of the VCLT, certain high-level officials are considered to have full powers by virtue of their position (de jure) and do not need to produce this document. These include:


Authentication

Once the negotiations are complete and the final wording of the treaty is agreed upon, the text must be authenticated. This is the formal procedure by which the text is established as authentic and definitive. It "freezes" the text, confirming that it is the final, agreed-upon version.

According to Article 10 of the VCLT, the common methods of authentication are:

It is crucial to understand that signing a treaty does not usually mean that the state is legally bound by it yet. The signature primarily signifies two things:

  1. That the state agrees the text is the final version.
  2. A good faith obligation under Article 18 of the VCLT to refrain from acts which would defeat the object and purpose of the treaty until the state has made its intention clear regarding ratification.

Ratification/Accession

This is the most critical step by which a state formally declares its consent to be bound by a treaty. It is a two-level process, involving both domestic and international actions.

Ratification

Ratification is the process used by states that have participated in the negotiation and signing of a treaty. It gives the state an opportunity to review the treaty at the national level and take the necessary legislative action before committing to it internationally.

  1. Domestic Procedure: The state follows its own constitutional rules. In many countries, this involves seeking approval from the national parliament or legislature. In India, under Article 73 of the Constitution, the executive branch of government holds the power to make and ratify treaties. While parliamentary approval is not constitutionally mandatory for all treaties, it is a common practice to seek it for significant treaties or those that require the enactment of a new domestic law to be implemented.
  2. International Procedure: After domestic approval, the state prepares a formal document called an "instrument of ratification." For a bilateral treaty, these instruments are exchanged between the two states. For a multilateral treaty, the instrument is deposited with a designated depositary (e.g., the Secretary-General of the United Nations). The state is legally bound from the moment of this exchange or deposit.

Accession

Accession is the method by which a state that did not sign the treaty (e.g., because it did not participate in the negotiations or missed the deadline for signature) can become a party. It has the same legal effect as ratification and is accomplished in a single step by depositing an "instrument of accession" with the depositary.



Reservations to Treaties

A reservation is a unilateral statement made by a state when it signs, ratifies, or accedes to a multilateral treaty, through which it purports to exclude or to modify the legal effect of certain provisions of the treaty in their application to that state. The practice of allowing reservations strikes a balance between two competing goals: maintaining the integrity and uniformity of the treaty, and encouraging the widest possible participation (universality) by allowing states to opt-out of provisions they cannot accept.


Conditions for valid reservations

The right to make a reservation is not unlimited. Article 19 of the VCLT sets out the conditions under which a reservation is permissible. A state may formulate a reservation unless:

  1. The reservation is prohibited by the treaty.
    Some treaties explicitly forbid any reservations to ensure that all parties are bound by the exact same obligations. For example, the Rome Statute of the ICC explicitly prohibits reservations.

  2. The treaty provides that only specified reservations, which do not include the reservation in question, may be made.
    A treaty may allow reservations to certain articles but not others. Any reservation that is not on the permitted list is invalid.

  3. The reservation is incompatible with the object and purpose of the treaty.
    This is the most important and most general rule. A state cannot make a reservation that undermines the core principles or the fundamental aim of the treaty. The "object and purpose" refers to the essential reason the treaty was created. Determining what is incompatible is often a matter of interpretation by the other state parties.

Example 1. State A decides to ratify a major international human rights convention whose primary object is to guarantee the right to life and prohibit torture. In its instrument of ratification, State A includes a reservation stating that "it reserves the right to use torture in situations of national emergency."

Answer:

This reservation would be considered invalid. The prohibition of torture is a central pillar and a core component of the "object and purpose" of almost any human rights treaty. Allowing a state to opt-out of this fundamental obligation would defeat the very purpose of the convention. Therefore, other states would likely object to this reservation on the grounds that it is incompatible with the treaty's object and purpose.



Entry into Force

Entry into force is the event that marks the beginning of a treaty's life as a legally binding instrument. It is the moment from which the treaty becomes operative, and the states that have consented to be bound are legally obligated to perform its provisions in good faith. This fundamental principle of compliance is known as pacta sunt servanda ("agreements must be kept"), which is codified in Article 26 of the VCLT.


Determining the Moment of Entry into Force

The rules for entry into force are determined by the treaty itself. Article 24 of the VCLT states that a treaty enters into force in such manner and upon such date as it may provide or as the negotiating states may agree. In the absence of such a provision, a treaty enters into force as soon as consent to be bound has been established for all the negotiating states.

Common methods include:

Entry into Force for Latecomers

For a state that ratifies or accedes to a multilateral treaty after it has already entered into force, the treaty will typically enter into force for that specific state on the date it deposits its instrument of ratification, or after a short waiting period (e.g., 30 days) as specified in the treaty. From that moment, it joins the existing community of state parties and is bound by the same rights and obligations.



Interpretation, Amendment, and Termination of Treaties



Interpretation of Treaties

The interpretation of treaties is the process of determining the meaning of the terms and provisions of a treaty to understand the scope of the rights and obligations agreed upon by the parties. Since treaties are the result of negotiations between states with different languages, cultures, and legal traditions, ambiguities and disagreements over meaning are common. The Vienna Convention on the Law of Treaties (VCLT) provides a structured and authoritative framework for interpretation in its Articles 31 and 32.


Rules of interpretation

The VCLT establishes a primary "general rule" of interpretation that integrates several approaches, supported by "supplementary means" that can be used in specific circumstances. This framework prioritizes the text of the treaty itself while allowing for context and purpose to be considered.

General Rule of Interpretation (Article 31 of VCLT)

Article 31 combines the textual, contextual, and teleological (object and purpose) schools of interpretation into a single, unified rule. It states that 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.

Furthermore, Article 31 provides that, along with the context, account shall be taken of:

Supplementary Means of Interpretation (Article 32 of VCLT)

Supplementary means, such as the preparatory work of the treaty (travaux préparatoires) and the circumstances of its conclusion, can be used in two situations:

  1. To confirm the meaning resulting from the application of Article 31.
  2. To determine the meaning when the interpretation according to Article 31 either (a) leaves the meaning ambiguous or obscure; or (b) leads to a result which is manifestly absurd or unreasonable.
Interpretation Rule Description
General Rule (Art. 31) Interpret in good faith, based on the ordinary meaning of the text, in its context, and in light of its object and purpose.
Context Includes the treaty text, preamble, annexes, and any related agreements made by all parties.
Subsequent Practice/Agreement How parties have interpreted or applied the treaty after its conclusion can clarify its meaning.
Supplementary Means (Art. 32) Used to confirm or clarify meaning. Includes preparatory work (travaux préparatoires) and circumstances of conclusion.


Amendment and Modification of Treaties

As circumstances change over time, states may find it necessary to alter the provisions of a treaty. The VCLT provides two distinct procedures for this: amendment, which involves all parties, and modification, which involves only some of them.


Amendment (Article 40)

An amendment is a formal revision of a treaty's provisions that affects all the parties. The process for amending a treaty is as follows:


Modification (Article 41)

A modification (or an inter se agreement) is an agreement between two or more parties to a multilateral treaty to alter the treaty's effects as between themselves only. This is permissible only under strict conditions:

  1. The possibility of such a modification must be provided for by the treaty itself; OR

  2. The modification is not prohibited by the treaty AND:

    • it does not affect the enjoyment by the other parties of their rights under the treaty or the performance of their obligations; and
    • it does not relate to a provision, derogation from which is incompatible with the effective execution of the object and purpose of the treaty as a whole.

The parties intending to conclude such a modification must notify the other parties of their intention.



Termination and Suspension of Treaties

Termination releases all parties from the obligation to perform the treaty, while suspension temporarily relieves them of this duty. Given the importance of treaty stability (pacta sunt servanda), the VCLT provides a limited and exhaustive list of grounds upon which a treaty may be lawfully terminated or suspended.


By consent

The simplest way to end a treaty is through the consent of the parties.


By material breach

A "material breach" of a treaty by one party may entitle the other parties to invoke the breach as a ground for terminating the treaty or suspending its operation (Article 60, VCLT).

A breach is "material" if it consists of:

Example 1. State A and State B sign a bilateral treaty agreeing to a mutual and verifiable reduction of their missile arsenals by 50% over five years. In the third year, State A discovers that State B, instead of reducing its arsenal, has secretly been increasing it.

Answer:

This would constitute a material breach. The provision to reduce missile arsenals is not just a minor clause; it is the central object and purpose of the treaty. State B's action in secretly increasing its arsenal is a violation of a provision essential to the accomplishment of the treaty's goal. Therefore, under Article 60 of the VCLT, State A is entitled to invoke this breach as a ground for terminating the treaty or suspending its operation in whole or in part.


By supervening impossibility of performance

A state may invoke the impossibility of performing a treaty as a ground for terminating it if the impossibility results from the permanent disappearance or destruction of an object indispensable for the execution of the treaty (Article 61, VCLT).

For example, if a treaty requires one state to ensure the flow of a river to another state, and the river permanently dries up due to geological shifts, performance becomes impossible. This ground cannot be invoked if the impossibility is the result of a breach by the party invoking it.


By fundamental change of circumstances (Rebus sic stantibus)

This is a very controversial and strictly limited doctrine, known as rebus sic stantibus ("things standing thus"). A state may only invoke a fundamental change of circumstances as a ground for termination if a set of very strict, cumulative conditions are met (Article 62, VCLT):

  1. The change must be of circumstances that existed at the time the treaty was concluded.
  2. The change must be fundamental.
  3. The change was not foreseen by the parties.
  4. The existence of the original circumstances was an essential basis of the consent of the parties to be bound.
  5. The effect of the change is to radically transform the extent of obligations still to be performed.

This ground cannot be invoked for a treaty that establishes a boundary.

Example 2. In 1977, State C (an upstream state) and State D (a downstream state) conclude a treaty to jointly build and operate a large dam system on a shared river for hydroelectric power and improved navigation. It is based on a shared socialist ideology and economic integration. In 1990, State C undergoes a revolution, abandons its socialist economy for a market-based one, and new scientific evidence emerges showing the project would cause catastrophic environmental damage.

Answer:

State C might try to invoke a fundamental change of circumstances to terminate the treaty. It would argue:

  • The political and economic system (socialist integration), an essential basis of consent, has fundamentally changed.
  • The emergence of new knowledge about environmental harm radically transforms the nature of the obligation, changing it from a project of 'socialist progress' to one of 'environmental destruction'.
  • This level of environmental damage was unforeseen in 1977.

This scenario is based on the Gabčíkovo-Nagymaros Project Case between Hungary and Slovakia, where the International Court of Justice recognized the existence of the doctrine of fundamental change of circumstances in customary law but found that the strict conditions had not been met in that specific case. This highlights the extremely high threshold for successfully invoking the doctrine.