Article 38(1) of the International Court of Justice’s statute identifies treaties as a source of law,
along with general principles and customs. Treaties occupy a very eminent position in
international law. They ensure friendly and peaceful relations of states with one another and are a
means by which international organizations take form, regulate and monitor their affairs. The
concept of the treaty has undergone significant changes over time. In earlier periods, treaties
used to be oral and a ceremony would be held where the parties would conclude it and swear an
oath to God, which used to act as the binding force of the treaty. Now, treaties must be written
and are legally binding between its parties.1
Drafted by the International Law Commission of the UN and taking force on 27 January 1980,
the Vienna Convention on the Law of Treaties set out some fundamental rules as to how treaties
are to operate and take form. More than half of the member states of the UN are a party to the
A treaty means a formal agreement between two or more independent Nations with references to
peace, alliance, commerce or other International relations.2
What is a Treaty?
Treaties are the principal source of Public International Law.
The Vienna Convention on the Law of Treaties defines a ‘treaty’ as ‘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’ (Article 2(1)(a)).
Treaties are commonly called 'agreements', 'conventions', `protocols' or `covenants' , and
less commonly `exchanges of letters'. Frequently, `declarations’ are adopted by the UN
General Assembly. Declarations are not treaties, as they are not intended to be binding,
1 Law of Treaties 1: Whatis a treaty? , https://ruwanthikagunaratne.wordpress.com/2013/05/26/law-of-treaties-
2 Meaning , Definition and meaning of treaties, https://www.srdlawnotes.com/2017/03/meaning-definition-and-
but they may be part of a process that leads ultimately to the negotiation of a UN treaty.
Declarations may also be used to assist in the interpretation of treaties.3
Kinds of treaty4
1) Law Making treaties
The term “law-making” treaty seems to be confusing, as it raises the question- Can treaties create
law? This term actually refers to the content and the subject matter of a treaty, which instead of
being contractual shall be statutory. The emergence of a subsisting need of international legal order
sparked a newfound interest in this type of treaty. The need of bringing rules which had statutory
force was felt rather than the existing rules which governed voluntary legal relations between
states. In cases of law-making treaties, the obligations are independent; they don’t require a
subsequent fulfilment of rules by other parties to it. These obligations have binding force and the
parties to these treaties must follow it. Unlike contracts, treaties have the power to make new
international tribunals, international waterways, mandates, etc.
2) Contractual treaties
They are usually applicable to treaties having a small number of parties and are most commonly
seen in bilateral treaties. These are treaties where parties are mutually dependent on each other for
specific treatment to gain benefits, and have rights and obligations towards each other. In reality,
treaties need to take care of both the statutory as well as the contractual function. The scope of
treaties is mostly perceived in a contractual framework. Unlike law-making treaties, which sets
out rules for conduct, rights, and duties between parties which have to take effect on the conclusion
of the treaty, contractual treaties are usually limited to, say, exchange of goods which one state
might not possess and require, or conveyances. Here, one party agrees to provide the other party
something it needs for something else in return, thereby forming a system like barter.
3 Law of Treaties 1: Whatis a treaty? , https://ruwanthikagunaratne.wordpress.com/2013/05/26/law-of-treaties-
4 Treaties , https://www.srdlawnotes.com/2017/08/termination-of-treaties.html
Types of treaty5
A. Bilateral treaties
Treaties involving two entities are bilateral treaties. It is not necessary that the treaty can only have
2 parties; there may be more than two parties, however, there should be only two states involved.
For example, the bilateral treaties between Switzerland and the European Union(EU) have 17
parties, which are divided into two parts, the Swiss and the EU and its member states. It is
important to note that by virtue of this treaty, obligations, and rights arise between the two entities
to it, i.e. the EU and the Swiss. This treaty does not give rise to obligations between the EU and
its member states.
B. Multilateral treaties
Treaties between three countries or more are multilateral treaties. They might be international or
domestic. They give rise to rights and obligations among all the parties, i.e. each signatory has
obligations towards all the other signatories.
Treaties with a higher number of participating states gain more international significance since it
reflects the importance of the treaty. However, there have been many crucial bilateral treaties too,
such as those emerging from Strategic Arms Limitation Talks. All treaties have different
purposes. Some set up international organizations through the UN Charter of 1945, whereas
others deal with issues such as visa regulations.
Custom and Treaties:6
Inter-relationship Custom and treaties are the two methods for the creation of the legally
binding rules ever since the beginning of the international community. In both, consent of
the States is reflected, and therefore, they did not impose obligations on those States who
did not wish to be bound by them. However, while in customary rules, consent of the States
is implied, in the treaties, consent is express. Moreover, customary rules are often not
precise and adequate, while treaty-rules are clear and precise. This has led to the
transformation of many customary rules into treaty rules.
5 International treaties , https://www.srdlawnotes.com/2017/03/meaning-definition-and-types-of_7.html
6 Treaties , Malgosia Fitzmaurice, https://opil.ouplaw.com/view/10.1093/law:epil/9780199231690/law-
The customary rules of international law cannot be regarded as to have ceased to exist if
they have been transformed into treaty rules. The court cannot be prevented to apply
customary rules in such cases. Thus, principles such as those of the non-use, force, non-
intervention, respect for the independence and territorial integrity of States, etc continue to
be binding as part of customary international law, despite the operation of provisions of
conventional law in which they have been incorporatedÂ (Nicaragua Case, ICJ. Rep.
The existence of identical rules in international treaty law and customary law has been
clearly recognized in the North Sea Continental Shelf Cases.
Schools of Treaty Interpretation7
Notwithstanding the very specific hierarchy of relevant considerations laid out in Articles 31 and
32, there are discernable tendencies among different scholars—and even among different
tribunals—to rely more heavily on one type of consideration than others in arriving at the final
interpretation of a treaty provision.
There are at least three commonly acknowledged "schools" or approaches to treaty interpretation,
which correspond to methods of construction of any legal text—including constitutions, statutes,
i. Textualist. The first school is textualism. All solid treaty interpretation begins with the
words of a provision itself, as they are commonly understood. VCLT Article 31, in
discussing treaty interpretation, calls for an examination of a text’s "ordinary meaning."
Many treaties are drafted in two or more languages, and it is vital to ascertain not only
which languages are "authentic," but also that there may be different shades of meanings
of terms in different languages.
ii. Intentionalist. Textualism can be a form of contextual reading of different provisions in a
treaty text, in order to reach a sensible result. Already one can see a tension between the
text of a treaty provision and the intent of the drafters. However, the second, intentionalist,
approach to treaty interpretation has never been popular in international law. Indeed, the
VCLT relegates sources shedding light on the intent of the drafters—including the
negotiating history (known as travaux préparatoires, or travaux) of a provision—to a
secondary role. They can be used only where the text is "ambiguous or obscure," or the
plain meaning of the text leads to a "manifestly absurd or unreasonable" result.
iii. Teleological. That leaves the third school of interpretation: seeking to effectuate the
purpose of a treaty, rather than slavishly following the text or attempting to divine the intent
of the drafters. Known in international law as a teleological approach, it can also be called
purposivism. It is captured in the VCLT’s requirement that treaties be construed in light of
their "object and purpose" and in view of "relevant rules of international law."
Statute of the International Court of Justice8
Sets forth the principles of international law, jurisdiction, and composition of ICJ
Article 38: body of laws that the court can apply to disputes between states
This is a codification of the sources of international law:
International conventions (international treaty)
International custom (a general practice accepted by law) this does not express agreements in
writing, but looks at the general practice or actual practice of states. You look at social facts:
how do the members of this society conduct themselves as an issue of obligation?
General principles: Works from the top down: not looking at the practice of states, but is rooted
in principles of natural law, logic, social necessity.
There is NO hierarchy, but in practice, which would we say is the most important and why?
Treaties are the most certain source of law. We need only interpret the provisions of the
treaty. But, does that make a treaty more important as a source of law?
Customary law tends to be more substantive. It requires widespread consistent practice
(Treaty law and customary law overlap a great deal) A treaty could possibly override a pre-
existing custom, and a subsequent custom might supplant a treaty.
Vienna Convention has codified much of what the ICJ said in articles 2, 19, 20, 21, and 229
Canada frequently strives to have a federal-state clause put into a treaty (or will enter a
reservation) which has the effect of reserving Canadas obligations at international law
concerning matters within the legislative jurisdiction of the provinces.
Note: An interpretive declaration differs from a reservation. The ILC defines it as a unilateral
statement, however phrased or named, made by a Statewhereby that Statepurports to specify or
clarify the meaning or scope attributed by the declarant to a treaty or to certain of its provisions.
Invalidity of treaty10
Part V of the Vienna Convention on The Law of Treaties, 1969, particularly Section 2 deals with
the invalidity of treaties. Articles 46-53 set out the ways to invalidate a treaty, i.e. make them void
8 Sources Of International LawAn Overview , Mohd Aqib Aslam, http://www.legalserviceindia.com/legal/article-
9 Vienna Convention on the Law of Treaties , https://www.refworld.org/docid/3ae6b3a10.html
10 Law of Treaties , https://legal.un.org/ilc/documentation/english/a_cn4_182.pdf
and unenforceable under international law. There are several reasons as to why an internationally
binding treaty may be declared as invalid. One of the reasons for invalidity is that they might be
riddled with problems ever since the time of formation. Content of the treaties and the mode by
which consent is obtained are the two grounds on which treaties may be invalidated.
It is important to note that invalidation is different from withdrawal and termination; the former
involves invalidation of consent right from the start, while the latter involves future alteration in
consent to be a signatory.
Formation of a treaty11
There is no concrete way of creating a treaty. It may be presented in different forms such as a
contract or an exchange of notes, as seen in the Rush-Bagot Agreement between Great Britain and
the U.S. for mutual disarmament on the Great Lakes. Most treaties, however, follow a similar
structure. Every treaty begins by introducing its preamble, which states the object of the treaties
and the parties to it. It is then followed by what the parties agreed upon. A statement of the period
may or may not follow; it depends on the time period for which the treaty shall exist. Next up,
reservations and then ratification clauses follow. Then, it ends with the signatures of the parties
involved along with the date and venue of ratification.
Additional articles may be further attached along with the declaration that they are equal in value
as to other clauses. Going by the Law of Treaty, the following steps form the essentials of
formation of a treaty-
Adoption of the text
Consent of all parties to a treaty is essential for adopting a text. If the treaty is being adopted at an
international conference, a two-thirds majority shall be required for the adoption of text unless
agreed upon otherwise.
Authentication of the text
As per the procedure mentioned in the text, a treaty shall be established to be authentic. On the
failure of such procedure, signatures or initials of representatives of the participating states may
be sufficient to deem the text to be definitive.
11 Concept of Treaties in International Law, Diganth Raj Sehgal , June 23, 2020 , https://blog.ipleaders.in/concept-
Expression of consent
This may be by way of signatures, ratification, acceptance, approval or accession or by exchanging
instruments required for the treaty.
Consent by signature
Provided that the treaty explicitly states that signature by the representative of a state shall be
sufficient to be declared as a party, or the negotiating states have mutually consented to signature
be sufficient, the representative’s signature expresses a state’s full intention to enter into a treaty.
Consent by exchange of instruments required by the treaty
If the states agree that exchange shall be equivalent to the expression of the consent to enter into
the treaty, then so shall be the case.
Consent by ratification, acceptance or approval
If the negotiating states are of the opinion that ratification shall be equivalent to expressing consent,
or the treaty provides for ratification, then it shall be an acceptable way of obtaining consent to the
treaty. Similarly, the same condition applies to consent expressed by approval or acceptance.
Consent expressed by accession
Consent to the treaty shall be obtained If the treaty provides for it or the negotiating states agree
Formulation of reservations
A state may while concluding the treaty expresses its reservations unless it’s prohibited by the
treaty, or if permitted shall violate with the object and intent of the treaty.
Termination of Treaties12 :
Treaties may terminate on any of the following grounds :
1) Expiry of Specific Period :
12 Termination of Treaties , https://www.srdlawnotes.com/2017/08/termination-of-treaties.html
When a treaty is concluded for a particular period, which expressly provided in treaty
contract then after the expiry of that period, treaty ipso facto comes to an end.
2) Where the main purpose/object of the treaty is fulfilled :
In case of treaties imposing no continuing obligations, they cease to operate on the
fulfillment of the object.
3) Termination by Mutual Consent :
It is an outcome of consensus. Treaty comes into existence by the consent of the party State.
So it can come to an end by mutual Consent.
4) One of the Party State Extinct :
When the existence of one of the party state comes to an end, generally in case of the
merger of one state into another state, the treaty stand terminated.
5) When that obligation of the treaty becomes incompatible with the Charter of United
Article 103 specifically provides that in the event of a conflict between the obligations of the
members of the United Nations and their obligations under any other agreement, their obligations
under the Charter shall prevail.
6) War Between Party States :
In a War, If the Party States are the enemy against each other, then contractual
obligations come to an end and treaty ipso facto stand terminated.
7) Dissolution by Withdrawal by Notice :
The treaties can be dissolved by a notice by either party to the other party. If no period
of the existence of the treaty is prescribed by the parties, then treaty can be determined by the
requisite period of the termination of treaties by a notice. When a prescribed period of notice is
given expressly in the treaty then it is to be strictly complied with.
8) Terms of treaty becoming injurious to State :
By such treaty either wholly or partly the terms of treaty become injurious to one of the
party state, thereby interest of one party state, likely to be adversely affected. In
such circumstances, there is conflict as to term and sovereignty of the state, whereby sovereignty
of that state is in danger. Its survival is more important than such obligations. In such cases of
conflict, the law makes it very clear and contractual obligation comes to an end.
9) Non- Performance of certain Essential Conditions :
If the Treaty grants a unilateral right of denunciation to one or all of the consenting
States in case of failure of certain essential conditions, the treaty comes to an end on the
happening of such contingency.
10) Doctrine of Rebus sic stantibus :
The meaning of doctrine Rebus sic stantibus is if by any unforeseen change, or circumstances
an obligation provided for in the treaty should imperil the existence of one of the State. and such
state has a right to demand and to be released from the contractual obligations. It means when the
terms of the agreement are injurious to one of the party State, or the purpose of treaty is over or
there are changes in the circumstances, or there is conflict with the status of or existence of one
of the party State, or when the object of treaty is no more there, then in such cases doctrine of
Rebus Sic Stantibus is made applicable and Treaty concluded comes to an end. This is based on
the basic principle of self Preservation and Development in accordance with the growth and
requirement of the nation.
11) Doctrine of Jus Cogens :
Lastly, a treaty may be declared void if it conflicts with a peremptory norm (it also called jus
cogens)of general International Law.
Suspension and Termination13
1. Implied by the conclusion of a later treaty-
On account of drafting a later treaty dealing with the same subject matter as its previous version,
the previous counterpart shall be deemed to be terminated, provided that the parties intend to be
governed by the new treaty or the provisions of both the treaties are so incompatible with each
other that both the treaties cannot be applicable at the same time. The previous treaty will be
terminated if it’s the implied or established intention of the signatories.
2. As a consequence of its breach-
There are different consequences for different kinds of treaties. If the treaty is bilateral and one of
the parties has caused a material breach of the treaty, then the other may use it to bring the treaty
to an end. If the treaty is multilateral, then default by one of the parties entitles the other parties to
terminate/suspend such treaty, wholly or partly by unanimous consent. Material breach, as
explicitly mentioned in Section 61 consists in the violation of a provision of the treaty which is of
the essence to it and forsaking the treaty.
3. Impossibility of performance-
The impossibility of fulfilling conditions as per the treaty is considered sufficient ground for the
suspension/ termination of a treaty. If the impossibility is permanent, i.e. the devastation makes
execution of the treaty impossible, the treaty may be terminated. However, if the impossibility is
temporary, the treaty may be suspended for the required duration.
However, if the impossibility of performance is due to the conduct and action of one the parties,
i.e. due to violation of a provision of the treaty or violation of any international obligations, the
treaty may not be terminated/ suspended.
4. Fundamental change of circumstances-
13 Termination of Treaties , https://www.srdlawnotes.com/2017/08/termination-of-treaties.html
Unforeseen changes which fundamentally affect the treaty may be sufficient to invoke termination/
revocation of the treaty, provided that the changes are “fundamental” i.e. initial existence of the
circumstances may affect the consent of parties to the treaty and that as a result, the obligations to
be performed under the treaty have been changed and transformed radically.
If the change is due to breach of treaty or any international obligations by one of the parties to the
treaty, then this article would not be invokable.
5. Rift of diplomatic or consular relations
Provided that the treaty demands the existence of hostile and diplomatic relations between its
parties, disturbance or severance of such relations shall have no effect on the treaty since it doesn’t
really affect the legal relationship among the parties.
6. Emergence of new jus cogens
If a new jus cogens or peremptory norm of general international law emerges after worldwide
assent to it, any treaty in violation of it shall be deemed to be terminated.
The Vienna Convention on the Law of Treaties lays down basic and fundamental principles to
govern treaties. The main principle on which the Convention operates is “pacta sunt servanda”,
i.e. all treaties must be followed in good force. It provides for various provisions such as
ratification, reservation, approval, conclusion, withdrawal, invalidation, termination of a treaty,
etc. The Convention is legally binding on its parties.
Treaties play an important role as the source of international law and occupy a colossal pedestal
in this field. Various sources, however principally treaties between states are considered
authoritative statements of international law. Treaties are the strongest and most binding type
because they represent consensual agreements between the countries who sign them.14
14 Sources Of International LawAn Overview , Mohd Aqib Aslam, http://www.legalserviceindia.com/legal/article-