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Glossary of terms used in international law relating to treaties and conventions. *


Accession is the act whereby a State that has not signed a treaty expresses its consent to become a party to that treaty by depositing an "instrument of accession". Accession has the same legal effect as ratification, acceptance or approval. The conditions under which accession may occur and the procedure involved depend on the provisions of the relevant treaty. Accession is generally employed by States wishing to express their consent to be bound by a treaty where the deadline for signature has passed. However, many modern multilateral treaties provide for accession even during the period that the treaty is open for signature.


Adoption is the formal act by which negotiating parties establish the form and content of a treaty. The treaty is adopted through a specific act expressing the will of the States and the international organizations participating in the negotiation of that treaty, e.g., by voting on the text, initialing, signing, etc. Adoption may also be the mechanism used to establish the form and content of amendments to a treaty, or regulations under a treaty.

Treaties that are negotiated within an international organization are usually adopted by resolution of the representative organ of that organization. For example, treaties negotiated under the auspices of the United Nations, or any of its bodies, are adopted by a resolution of the General Assembly of the United Nations.

Where an international conference is specifically convened for the purpose of adopting a treaty, the treaty can be adopted by a vote of two thirds of the States present and voting, unless they have decided by the same majority to apply a different rule.


Whereas in the last century the term "convention" was regularly employed for bilateral agreements, it is now generally used for formal multilateral treaties with a broad number of parties. Conventions are normally open for participation by the international community as a whole, or by a large number of States. Usually instruments negotiated under the auspices of an international organization are entitled conventions. The same holds true for instruments adopted by an organ of an international organization.


Interpretative declaration

An interpretative declaration is a declaration by a State as to its understanding of some matter covered by a treaty or its interpretation of a particular provision. Unlike reservations, declarations merely clarify a State's position and do not purport to exclude or modify the legal effect of a treaty.

The Secretary-General, as depositary, pays specific attention to declarations to ensure that they do not amount to reservations. Usually, declarations are made at the time of signature or at the time of deposit of an instrument of ratification, acceptance, approval or accession. Political declarations usually do not fall into this category as they contain only political sentiments and do not seek to express a view on legal rights and obligations under a treaty.

Mandatory declaration

A mandatory declaration is a declaration specifically required by the treaty itself. Unlike an interpretative declaration, a mandatory declaration is binding on the State making it.

Optional declaration

An optional declaration is a declaration that a treaty specifically provides for, but does not require. Unlike an interpretative declaration, an optional declaration is binding on the State making it.

Entry into force

Definitive entry into force

Entry into force of a treaty is the moment in time when a treaty becomes legally binding on the parties to the treaty. The provisions of the treaty determine the moment of its entry into force. This may be a date specified in the treaty or a date on which a specified number of ratifications, approvals, acceptances or accessions have been deposited with the depositary. The date when a treaty deposited with the Secretary-General enters into force is determined in accordance with the treaty provisions.

Entry into force for a State

A treaty that has already entered into force may enter into force in a manner specified in it for a State or international organization that expresses its consent to be bound by it after its entry into force. See article 24 of the Vienna Convention 1969.

Provisional entry into force

Provisional entry into force may be allowed by the terms of a treaty, for example, in commodity agreements. Provisional entry into force of a treaty may also occur when a number of parties to a treaty that has not yet entered into force decide to apply the treaty as if it had entered into force. Once a treaty has entered into force provisionally, it creates obligations for the parties that agreed to bring it into force in that manner. See article 25(1) of the Vienna Convention 1969.


A protocol, in the context of treaty law and practice, has the same legal characteristics as a treaty. The term protocol is often used to describe agreements of a less formal nature than those entitled treaty or convention. Generally, a protocol amends, supplements or clarifies a multilateral treaty. A protocol is normally open to participation by the parties to the parent agreement. However, in recent times States have negotiated a number of protocols that do not follow this principle. The advantage of a protocol is that, while it is linked to the parent agreement, it can focus on a specific aspect of that agreement in greater detail.

Ratification, acceptance, approval

Ratification, acceptance and approval all refer to the act undertaken on the international plane, whereby a State establishes its consent to be bound by a treaty. Ratification, acceptance and approval all require two steps:

  1. The execution of an instrument of ratification, acceptance or approval by the Head of State, Head of Government or Minister for Foreign Affairs, expressing the intent of the State to be bound by the relevant treaty; and
  2. For multilateral treaties, the deposit of the instrument with the depositary; and for bilateral treaties, the exchange of the instruments between parties.

Ratification, acceptance or approval at the international level indicates to the international community a State's commitment to undertake the obligations under a treaty. This should not be confused with the act of ratification at the national level, which a State may be required to undertake in accordance with its own constitutional provisions, before it consents to be bound internationally. Ratification at the national level is inadequate to establish the State's consent to be bound at the international level.


A reservation is a statement made by a State by which it purports to exclude or alter the legal effect of certain provisions of a treaty in their application to that State. A reservation may enable a State to participate in a multilateral treaty that it would otherwise be unable or unwilling to participate in. States can make reservations to a treaty when they sign, ratify, accept, approve or accede to it. When a State makes a reservation upon signing, it must confirm the reservation upon ratification, acceptance or approval. Since a reservation purports to modify the legal obligations of a State, it must be signed by the Head of State, Head of Government or Minister for Foreign Affairs. Reservations cannot be contrary to the object and purpose of the treaty. Some treaties prohibit reservations or only permit specified reservations.


Definitive signature (signature not subject to ratification)

Definitive signature occurs where a State expresses its consent to be bound by a treaty by signing the treaty without the need for ratification, acceptance or approval. A State may definitively sign a treaty only when the treaty so permits. A number of treaties deposited with the Secretary-General permit definitive signature. See article 12 of the Vienna Convention 1969.

Simple signature (signature subject to ratification)

Simple signature applies to most multilateral treaties. This means that when a State signs the treaty, the signature is subject to ratification, acceptance or approval. The State has not expressed its consent to be bound by the treaty until it ratifies, accepts or approves it. In that case, a State that signs a treaty is obliged to refrain, in good faith, from acts that would defeat the object and purpose of the treaty. Signature alone does not impose on the State obligations under the treaty.


Treaty is a generic term embracing all instruments binding under international law, regardless of their formal designation, concluded between two or more international juridical persons. Thus, treaties may be concluded between:

  1. States;
  2. International organizations with treaty-making capacity and States; or
  3. International organizations with treaty-making capacity.

The application of the term treaty, in the generic sense, signifies that the parties intend to create rights and obligations enforceable under international law.

The Vienna Convention 1969 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)). Accordingly, conventions, agreements, protocols, and exchange of letters or notes may all constitute treaties. A treaty must be governed by international law and is normally in written form. Although the Vienna Convention 1969 does not apply to non-written agreements, its definition of a treaty states that the absence of writing does not affect the legal force of international agreements.

No international rules exist as to when an international instrument should be entitled a treaty. However, usually the term treaty is employed for instruments of some gravity and solemnity.

Bilateral treaty

A bilateral treaty is a treaty between two parties.

Multilateral treaty

A multilateral treaty is a treaty between more than two parties.

The terms and the explanations mentioned here are those provided by the UN in the UN web site. For a detail list of terms and further explanations please log on to

Posted on 2004-02-17

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