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This article is written by Millia Dasgupta, from Jindal Global Law School. This article covers the principle of Pacta Sunt Servanda. 


It is a Latin term that means agreements must be kept. It is present in both Civil law and international law. In international law, it means that every treaty is binding upon the parties and they must be executed in good faith. Good faith is a sincere intention to carry out obligations without malice. The parties under this treaty must fulfil their promises and obligations to the best of their abilities. This is subject to some conditions which we shall be discussing later on in the article. 


The principle can be traced back to religious origins. In the Koran, it has been stated that “Be true to the obligations which you undertake”. This religious principle in the Middle East soon manifested in commerce and ruled commercial contracts and transactions.

The Romans also respected this principle and was an extremely important part of their judicial workings. It even had a great role to play in Christianity. 

During the renaissance, this principle was established in the theories of Machiavelli and soon became an important part of International law. 

What are treaties?

It is a law of treaty. They are also known as conventions (large scale treaty), pact, exchange of letters, protocol (amendment to the treaty), covenant, etc. They are formal written agreements and are between ‘actors’ of international law. Actors can also be countries, sovereign and non-sovereign nations and international organizations.

The codified law on treaties is the Vienna Convention on the law of Treaties (VCLT). It consists of a preamble, divided into 8 parts and 85 articles and came into force on Jan 27th, 1980. Non-sovereign states can also conclude treaties, colonies, trust territory, ‘Protectorate, Vassal State can also be a part of this treaty. (definition of terms) 

Treaties can be classified into two categories- law-making treaties that are treaty that are large scale and treaties that are contracts which are usually for a specific issue.

International law is silent on the fact that which treaty is valid and which is invalid. Thus, it seems like the states decide which treaty is valid or not. The treaty is also invalid if they violate the general principles of international law. These treaties are also open to revision but revision and amendment must be done according to proper procedure. 

Laws regarding this Principle

General Principle Of Law

The law embodies an important principle in the General Principles of Law. The General Principles of Law are sources of international law. The principles of Pacta Sunt Servanda are also embodied in the Permanent Court of Justice and The International Court of Justice. With regards to the UN, it is believed that all member nations are ‘civilized’ and are expected to follow the principles of Pacta Sunt Servanda when dealing with obligations, agreement and promises. This is keeping in mind that the parties involved in these treaties and international agreements have given their consent, as international law is a consent-based system.

The Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations (1970)

It states that every UN state in good faith must follow the following obligations:

  • Obligations under the UN Charter,
  • General recognized principles and laws under international law,
  • Obligations under valid treaties. 

It also states that even under conflicts between these two states, the obligations under the charter must prevail. Even in the process of exercising their own sovereign rights, the countries must keep in mind their obligations to the treaties as well. 

It must be noted that ‘obligations’ does not mean only duty. Here obligation means the states must perform their duties and also keep in mind their rights. These rights should also be expressed in good faith.

Article 26 of the Vienna Convention

It is under this very heading that the principle of ‘Pacta Sunt Servanda’ is established. This article is under Part III, section 1 of the Vienna conventions which lays out all the principles the party must observe when entering a treaty.

The Article states “Every treaty in force is binding upon the parties to it and must be performed by them in good faith.” There is also a prerequisite to this where the states must have given their consent to enter such a treaty. 

Such a law was adopted in the convention to find a space for interstate relations where obligations are respected and carried out in good faith. The principles of good faith and free consent of this principle is largely seen in other aspects of international law. 

Scope Of Pacta Sunt Servanda

According to Article 18 of the VLCT, states are asked to refrain from doing any acts which would hamper the outcome of the treaty. This is under the prerequisites that it has signed the treaty that has been subsequently ratified. This is until it has made its intentions clear that it does not want to be a party to the treaty. This is also subject to the fact that its entry into the treaty has not been unduly delayed. 

Under this principle, certain laws are also declared to be recognised and are thus valid. It ratifies the principle of ‘lex specialis’ and ascertains that laws must be obeyed. 

Exercising Pacta Sunt Servanda

Judge Lauterpacht in the case of Norwegian loans case in 1957 observed that “Unquestionably, the obligation to act in accordance with good faith being a general principle of law” is also a part of international law. 

According to Article 27 of the Vienna Convention, one can not use the defence that their domestic laws prevent them to act out a treaty which they consented to, but in certain cases where the treaty violates a ‘fundamental internal law’ of the country who has consented, then the treaty will be deemed invalid. (Section 46 of the Vienna Convention

In the case of ‘treatment of Polish Nationals and Other Persons of Polish Origins and Speech’, it was held that one cannot expect a consenting country to violate their own constitution in order to abide by rules of a treaty. 

Thus, if the treaty does not violate a fundamental law, the countries must abide by the rules of the treaty even if they are non-enforceable by their municipal laws. In some cases, the countries are required to incorporate laws from the treaty in their own municipal laws. The ‘Convention on the Settlement of Investment Disputes Between States and Nationals of Other States’ provides that countries shall be required to take legislative steps in order to ensure that the guidelines of the treaty are followed. 

Article 18 of the Vienna Convention provides that States must refrain from acts that would defeat the purpose of the treaty. This duty becomes enforceable only when the country has signed or exchanged instruments which constitute ratification of the treaty. This duty applies even if the entry of the treaty becomes enforceable later on. The words ‘defeat the object and purpose of the treaty’ were inserted and replaced by the words ‘tending to frustrate the object of a proposed treat’ as such words seemed vague.

Article 25 of the Vienna Convention allows for certain clauses of the treaty to be changed in the future. This is subject to the fact that the treaty explicitly states that such clauses can be changed in the future and that such changes do not defeat the purpose of the treaty itself.

Can violation of domestic law on treaty-making be a reason for non-compliance with international obligations in the form of treaties?

It may be possible that certain clauses of a treaty may clash with domestic laws of the State. So what do countries do then? Can they violate the principle of ‘Pacta Sunt Servanda’ on the basis of their domestic laws? According to Article 46 and 52 of the Vienna Convention, that will not be taken as an excuse and the treaty is still required to be followed. 

Article 27 states that “A party may not invoke the provisions of its internal law as justification for its failure to perform a treaty. This rule is without prejudice to article 46”. Part two of the article further elaborates that ‘an act is a violation of it is evident to the State that such an act would go against the normal practice and good faith.’

But Article 52 of the Vienna Convention safeguards States from Article 46 by stating that a treaty is void if its clauses have been “procured by the threat or use of force in violation of the principles of international law embodied in the Charter of the United Nations”. Thus, if such clauses of the treaty that violate the domestic laws have been established through force, then such a treaty will not be valid.

Criticisms of use Of Pacta Sunt Servanda- Case Law 

Nuclear Test Case, Aust v France

The Nuclear Test case, that was a case between Australia and France is still a great source of anger and agitation between south pacific nations of Australia and New Zealand as a result of atrocious environmental vandalism by the republic of France.

From the 1960s, the conducting tests of Nuclear weapons began at Mururoa Atoll in the South Pacific. From 1966 to the early 1970s, this included atmospheric testing. Australia and New Zealand argued that such practices resulted in radioactive particles spreading throughout the world. In order to stop the testing, they applied to the International Court of Justice. The french counter-argued that the court lacked jurisdiction. They also published a public statement that they no longer needed atmospheric testing. 

Australia and New Zealand were not satisfied with the public statement as nothing stopped France from changing their minds and continuing atmospheric nuclear testing.

The International Court of Justice denied their second appeal saying that the French declaration has already achieved what Australia wanted, that is an end to nuclear testing.

On the question of the reliability of the French statement, the court relied on the doctrine of Pacta Sunt Servanda (i.e Promises must be kept). They added on “Trust and confidence are inherent in international cooperation, in particular in an age when this cooperation in many fields is becoming increasingly essential”.

Just as the very rule of Pacta Sunt Servanda in the laws of treaties is based on good faith, so also is the binding character of an international obligation assumed by unilateral declaration.

“Thus interested States may take cognizance of unilateral declarations and place confidence in them and are entitled to require that the obligation thus created should be respected.”

In the end, the French did stop the atmospheric testing but they continued underground testing as long as 1996 causing extreme harm to the geology of Australia.


In this article, we had discussed what is the principle of Pacta Sunt Servanda. We also discussed its history and saw that this principle has deep roots in ancient history. 

Before going deep into the scope and application, we discussed what a treaty is and what is a valid and an invalid treaty. 

We then discussed the various laws around it such as The General principle of Law which is a source of international law, The Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations and Article 26 of the Vienna Convention

We also discussed the scope of the principle and established that states who are bound by such a principle must have given their consent in order to be a part of such a treaty. 

We even discussed the various laws involved when exercising Pacta Sunt Servanda such as Article 18, 27 and 46 of the Vienna Convention. We also addressed the question of whether states are bound to follow treaties which violate their domestic laws. 

Lastly, we saw how the principle of Pacta Sunt Servanda can be misused through the case of Australia vs France.


Lukashuk, I. I. “The Principle Pacta Sunt Servanda and the Nature of Obligation Under International Law.” The American Journal of International Law, vol. 83, no. 3, 1989, pp. 513–518.  International_Law

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