A treaty is an international agreement concluded between states in a written form governed by international law where they are embodied in a single instrument or several instruments.  Treaties are means by which states enter engagements with each other.  They generally deal with matters of international concern, such as international trade, environmental and human rights.

The law in relation to treaties itself is codified in a treaty, the 1969 Vienna Convention on Treaties. The Vienna Convention was produced by the International Law Commission and the UN conference on the law of treaties.  It refers to treaties in written forms between states.

Treaty is a general term.  It may equally be referred to as a convention, protocol, declaration, agreement, concordat or etc. A  treaty need not be in any particular form.  It may be quite informal such as by way of a joint declaration determining a particular matter or issue.

A treaty is intended to create binding legal agreements and relations and there must be an intention that it is to be a binding agreement.  Some types of agreements referred to as soft law, are not legally binding in the sense of being enforceable in court.  However, some such agreements may become accepted as treaties or become norms of international law.

Treaties may be entered between states, states and international organizations and international organizations themselves.

Authority to Enter

The question of authority and power arises in the conclusion of treaties.  A person or body which enters the treaties must have the appropriate power to do so.  Certain persons and entities such as the head of state,  government, minister for foreign affairs and heads of diplomatic missions, may have the appropriate powers depending on the nature of the treaty and the circumstances.

The general principle is that apart from the above, a person is considered as representing a state for the purpose of signifying its consent to be bound by a treaty if he produces evidence of full power unless it appears in the practice of the state concerned or other circumstances and to dispense with full powers.

Credentials may be contrasted with full powers. Credentials are submitted to an international organization or a government hosting an international conference by a delegate attending to negotiate a multilateral treaty.

They authorize the delegate to adopt the text of the treaty and sign a final act.  This may require specific instructions and ratification from the government.

Becoming Bound

The consent of a state to the treaty might be by exchange of instruments, ratification, signature, approval, accession or other means indicating agreement.  The Vienna Convention lists a number of means by which states may confirm their consent to be bound but allows other methods.

The signature of a treaty may or may not be subject to subsequent ratification, acceptance or approval.  If this is the case, then it is an intermediate step only pending such ratification.  It is not, however without legal consequences.

The signature expresses consent to being bound, where it is the final stage.  A signature ad referendum is a signature indicating that it requires further consent (not usually in the sense of a  referendum of the people).

A ratification is a formal act by the head of state through which approval is given to obligations undertaken.

Accession is the means by which a state gives consent to becoming a party to a treaty that it is not in a position to sign.  The state may accede to a treaty only if the treaty so allows or the parties otherwise agree.  This may happen in relation to a treaty for a regional group.

Acceptance and approval is widely used to express consent and is regulated by the Vienna Conventions.  It has the same legal effect as ratification.  It is intended to simplify procedures avoiding conditions in Constitutions that may be applicable.  It may require obtaining parliamentary consent before acceptance.


Treaties may be voidable or void.  A void treaty is void from the beginning and does not have a legal effect.  A voidable treaty is capable of being avoided. In the case of a multilateral treaty, the effect of finding voidability is that the consent of a particular member is invalidated, but it does not invalidate the treaty as a whole

The failure to comply with an internal law in relation to the conclusion of a treaty is only a ground for invalidating consent if the failure was manifest. This may arise for example, where it is apparent that a particular entity does not have authority to conclude the treaty or where representatives who purport to enter the treaty are clearly acting beyond their authority.

Fraud and corruption are grounds for the invalidation of a treaty. Coercion applies where there is a threat of force. Coercion will render the treaty void from its inception A  notorious example of coercion of representatives involved the establishment of a German protectorate in 1939 under pressure from the Nazi government.


Amendments to treaties are distinct from revisions.  A revision is a more comprehensive process.  A diplomatic conference is commonly convened to revise and amend the treaty.  Amendments are subject to approval of the party.

In the cases of some treaties, they may themselves allow for amendments within their scope.  Alternatively, there may be procedures which deem them to be accepted unless rejected.


The Vienna Convention provides for the suspension and termination of treaties.  The treaties themselves may contain grounds on which they may be terminated.  External grounds may involve a breach of obligation. Internal grounds may allow a party to withdraw in accordance with the provisions of the treaty.  A ]arty may generally withdraw with the consent of all parties at any time following consultations.

Treaties may provide for suspension of the treaties as regards all parties or some parties on conditions and for reasons set out.

Some treaties are of their nature temporary and will expire after that period.  Others contemplate being terminated by the resolution of the parties in accordance with a procedure.  This is the most common position.


The basic principle of international law is that pacta sunt servanda. Good faith is part of this principle.  It has been said that the principle of good faith may inform the literal meaning of a treaty so to that the parties apply it in a reasonable manner and in order to realise the purpose of the treaty.

The following are commonly recited principles of interpretation of treaties.  Treaties are to be interpreted on the basis of their actual text.  Subject to the principle of contemporaneity where applicable, where it had to be given a normal, natural and unstrained meaning as they occur.

This may be displaced only by direct evidence that the terms are understood in a different manner to their natural and ordinary meaning or if his interpretation would lead to an absurd or unreasonable result.

Treaties are to be interpreted as a whole.  The individual parts in the chapters are not to be interpreted out of context. Treaties are to be interpreted with reference to their declared and apparent objects and purposes.

They are to be treated so as to give the fullest effect consistent with the normal sense of the words to the test as a whole in a way that reason and meaning can be attributed to every part of the text. Recourse may be had to subsequent practice.  They are to be treated in the light of the linguistic use current at the time they were concluded.

Approaches to Interpretation

There are three broad schools of interpretation, namely the subjective or intentional approach, the objective or textual approach or the teleological or purposive approach. They are reflected in the above principles.

The Vienna Convention provides that a treaty is to be interpreted in good faith and in accordance with its ordinary meaning. Effect is to be given to the terms of the treaty in the context of its objects and purpose.  This is in accordance with international customary law.

The preparatory materials may be used to confirm the meaning of a treaty or as an aid to interpretation. Where there is ambiguity or obscurity or the words’ literal meaning would lead to an absurd or unreasonable result.

The Vienna Convention provides that the treaty should be interpreted in light of its object and purpose.  The principle of effectiveness provides that a treaty, when open to two interpretations, should be interpreted with effect, good faith and the objects and purposes of the treaty.  The provisions of the treaty must be supposed to have been intended to have significance and be necessary to express the intended meaning.

The instrument as a whole and each of its provisions must be taken to have been intended to achieve some end, and an interpretation which makes the text ineffective in achieving that object is incorrect.

A dynamic interpretation has been employed in relation to human rights law.  It may be contentious and disputed.  A dynamic interpretation implies evolution over time in the context of societal norms.  This is justified by reference to the special states of such conventions.  It is justified in the basis of the objective legal order and the character of the obligations undertaken by the parties.

A treaty drawn up in different languages may declare which is to be authentic. If there is none such, each is to be considered authentic and accordingly authoritative.  This may lead to issues of ambiguity and obscurity.

Reservation & Declaration

A reservation is a unilateral statement made by a state when signing, ratifying or approving a treaty which purports to exclude or modify the effect of provisions of the treaty as they apply to the state concerned.  Different approaches have been taken to reservations.

If they are accepted by all parties, there is unlikely to be controversy/ A state which has made a reservation that has been objected to by one or more other states but not others may be regarded as a party to the convention if the reservation is compatible with the object and purpose of the treaty.  Otherwise, the state cannot be regarded as a party to the convention.

If a  state party objects to a reservation attached to the signature or ratification of another, the treaty will enter into force and the reservation will be effective unless a contrary intention is definitively expressed by the objecting party.  Exceptionally, the body itself, such as in the case of the European Court of Human Rights, has an institutional procedure to deal with reservations.

Declarations are sometimes appended to treaties to explain how the state understands its obligations.  However, if they purport to change the obligations in the treaty, they may be regarded as part of the treaty itself rather than as interpretative material.  A question arises as to whether it may not be accepted by other parties.

Breach & Termination

The guiding principles of treaties are reciprocity and mutuality.  One view is that a material breach, however serious, does not end the treaty but  gives parties the right to invoke grounds for terminating it or suspending its operation. Article 60 of the Vienna Convention deals with the consequence of a breach of treaty obligations.

Issues arise as to whether the consequence of the breach must be dealt with within the framework of the treaty.

The International Court of Justice has tended to take interpretations that do not involve repudiation of the treaties but seek to regulate termination within the context of the treaty itself.  Breach of a treaty might justify a state taking countermeasures even if it does not constitute a ground of termination.

The permanent disappearance or destruction of an object indispensable for the execution of a treaty is ground for termination.  This is interpreted narrowly by the International Court of Justice.  If the impossibility is due to the breach by one party, a state may not just invoke its own failure of performance as grounds for terminating the treaty.

A fundamental change of circumstances is a controversial ground for the termination of a treaty. A fundamental change of r circumstances which determines the parties to accept the treaty if it results in a radical transformation of the extent of obligations imposed on them may, under certain conditions, allow the affected party to invoke a termination or suspension of the treaty.


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