(from the United
Nations Treaty Collection)
This introductory note seeks to provide a basic - but not
an exhaustive - overview of the key terms employed in the United Nations Treaty Collection
to refer to international instruments binding at international law: treaties, agreements,
conventions, charters, protocols, declarations, memoranda of understanding, modus vivendi
and exchange of notes. The purpose is to facilitate a general understanding of their scope
Over the past centuries, State practice has developed a
variety of terms to refer to international instruments by which States establish rights
and obligations among themselves. The terms most commonly used are the subject of this
overview. However, a fair number of additional terms have been employed, such as
"statutes", "covenants", "accords" and others. In spite of
this diversity of terminology, no precise nomenclature exists. In fact, the meaning of the
terms used is variable, changing from State to State, from region to region and instrument
to instrument. Some of the terms can easily be interchanged: an instrument that is
designated "agreement" might also be called "treaty".
The title assigned to such international instruments thus
has normally no overriding legal effects. The title may follow habitual uses or may relate
to the particular character or importance sought to be attributed to the instrument by its
parties. The degree of formality chosen will depend upon the gravity of the problems dealt
with and upon the political implications and intent of the parties.
Although these instruments differ from each other by title,
they all have common features and international law has applied basically the same rules
to all of these instruments. These rules are the result of long practice among the States,
which have accepted them as binding norms in their mutual relations. Therefore, they are
regarded as international customary law. Since there was a general desire to codify these
customary rules, two international conventions were negotiated. The 1969 Vienna Convention
on the Law of Treaties ("1969
Vienna Convention"), which entered into force
on 27 January 1980, contains rules for treaties concluded between States. The 1986 Vienna
Convention on the Law of Treaties between States and International Organizations or
between International Organizations ("1986 Vienna Convention"),
which has still not entered into force, added rules for treaties with international
organizations as parties. Both the 1969 Vienna Convention and the 1986 Vienna Convention
do not distinguish between the different designations of these instruments. Instead, their
rules apply to all of those instruments as long as they meet certain common requirements.
Article 102 of the Charter of the United Nations provides that "every treaty and
every international agreement entered into by any Member State of the United Nations after
the present Charter comes into force shall as soon as possible be registered with the
Secretariat and published by it". All treaties and international agreements
registered or filed and recorded with the Secretariat since 1946 are published in the
UNTS. By the terms "treaty" and "international agreement", referred to
in Article 102 of the Charter, the broadest range of instruments is covered. Although the
General Assembly of the UN has never laid down a precise definition for both terms and
never clarified their mutual relationship, Article1 of the General Assembly Regulations to
Give Effect to Article 102 of the Charter of the United Nations provides that the
obligation to register applies to every treaty or international agreement "whatever
its form and descriptive name". In the practice of the Secretariat under Article 102
of the UN Charter, the expressions "treaty" and "international
agreement" embrace a wide variety of instruments, including unilateral commitments,
such as declarations by new Member States of the UN accepting the obligations of the UN
Charter, declarations of acceptance of the compulsory jurisdiction of the International
Court of Justice under Article 36 (2) of its Statute and certain unilateral declarations
that create binding obligations between the declaring nation and other nations. The
particular designation of an international instrument is thus not decisive for the
obligation incumbent on the Member States to register it.
It must however not be concluded that the labelling of
treaties is haphazard or capricious. The very name may be suggestive of the objective
aimed at, or of the accepted limitations of action of the parties to the arrangement.
Although the actual intent of the parties can often be derived from the clauses of the
treaty itself or from its preamble, the designated term might give a general indication of
such intent. A particular treaty term might indicate that the desired objective of the
treaty is a higher degree of cooperation than ordinarily aimed for in such instruments.
Other terms might indicate that the parties sought to regulate only technical matters.
Finally, treaty terminology might be indicative of the relationship of the treaty with a
previously or subsequently concluded agreement.
The term "treaty" can be used as a common generic
term or as a particular term which indicates an instrument with certain characteristics.
(a) Treaty as a generic term: The term "treaty"
has regularly been used as a generic term embracing all instruments binding at
international law concluded between international entities, regardless of their formal
designation. Both the 1969 Vienna Convention and the 1986 Vienna Convention confirm this
generic use of the term "treaty". The 1969 Vienna Convention 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". The 1986 Vienna Convention
extends the definition of treaties to include international agreements involving
international organizations as parties. In order to speak of a "treaty" in the
generic sense, an instrument has to meet various criteria. First of all, it has to be a
binding instrument, which means that the contracting parties intended to create legal
rights and duties. Secondly, the instrument must be concluded by states or international
organizations with treaty-making power. Thirdly, it has to be governed by international
law. Finally the engagement has to be in writing. Even before the 1969 Vienna Convention
on the Law of Treaties, the word "treaty" in its generic sense had been
generally reserved for engagements concluded in written form.
(b) Treaty as a specific term: There are no consistent
rules when state practice employs the terms "treaty" as a title for an
international instrument. Usually the term "treaty" is reserved for matters of
some gravity that require more solemn agreements. Their signatures are usually sealed and
they normally require ratification. Typical examples of international instruments
designated as "treaties" are Peace Treaties, Border Treaties, Delimitation
Treaties, Extradition Treaties and Treaties of Friendship, Commerce and Co-operation. The
use of the term "treaty" for international instruments has considerably declined
in the last decades in favor of other terms.
The term "agreement" can have a generic and a
specific meaning. It also has acquired a special meaning in the law of regional economic
(a) Agreement as a generic term: The 1969 Vienna Convention
on the Law of Treaties employs the term "international agreement" in its
broadest sense. On the one hand, it defines treaties as "international
agreements" with certain characteristics. On the other hand, it employs the term
"international agreements" for instruments, which do not meet its definition of
"treaty". Its Art.3 refers also to "international agreements not in written
form". Although such oral agreements may be rare, they can have the same binding
force as treaties, depending on the intention of the parties. An example of an oral
agreement might be a promise made by the Minister of Foreign Affairs of one State to his
counterpart of another State. The term "international agreement" in its generic
sense consequently embraces the widest range of international instruments.
(b) Agreement as a particular term: "Agreements"
are usually less formal and deal with a narrower range of subject-matter than
"treaties". There is a general tendency to apply the term "agreement"
to bilateral or restricted multilateral treaties. It is employed especially for
instruments of a technical or administrative character, which are signed by the
representatives of government departments, but are not subject to ratification. Typical
agreements deal with matters of economic, cultural, scientific and technical co-operation.
Agreements also frequently deal with financial matters, such as avoidance of double
taxation, investment guarantees or financial assistance. The UN and other international
organizations regularly conclude agreements with the host country to an international
conference or to a session of a representative organ of the organization. Especially in
international economic law, the term "agreement" is also used as a title for
broad multilateral agreements (e.g. the commodity agreements). The use of the term
"agreement" slowly developed in the first decades of this century. Nowadays by
far the majority of international instruments are designated as agreements.
(c) Agreements in regional integration schemes: Regional
integration schemes are based on general framework treaties with constitutional character.
International instruments which amend this framework at a later stage (e.g. accessions,
revisions) are also designated as "treaties". Instruments that are concluded
within the framework of the constitutional treaty or by the organs of the regional
organization are usually referred to as "agreements", in order to distinguish
them from the constitutional treaty. For example, whereas the Treaty of Rome of 1957
serves as a quasi-constitution of the European Community, treaties concluded by the EC
with other nations are usually designated as agreements. Also, the Latin American
Integration Association (LAIA) was established by the Treaty of Montevideo of 1980, but
the subregional instruments entered into under its framework are called agreements.
The term "convention" again can have both a
generic and a specific meaning.
(a) Convention as a generic term: Article 38 (1) (a) of the
Statute of the International Court of Justice refers to "international conventions,
whether general or particular" as a source of law, apart from international customary
rules and general principles of international law and - as a secondary source - judicial
decisions and the teachings of the most highly qualified publicists. This generic use of
the term "convention" embraces all international agreements, in the same way as
does the generic term "treaty". Black letter law is also regularly referred to
as "conventional law", in order to distinguish it from the other sources of
international law, such as customary law or the general principles of international law.
The generic term "convention" thus is synonymous with the generic term
(b) Convention as a specific term: Whereas in the last
century the term "convention" was regularly employed for bilateral agreements,
it now is 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 the instruments negotiated under the auspices of
an international organization are entitled conventions (e.g. Convention on Biological
Diversity of 1992, United Nations Convention on the Law of the Sea of 1982, Vienna
Convention on the Law of Treaties of 1969). The same holds true for instruments adopted by
an organ of an international organization (e.g. the 1951 ILO Convention concerning Equal
Remuneration for Men and Women Workers for Work of Equal Value, adopted by the
International Labour Conference or the 1989 Convention on the Rights of the Child, adopted
by the General Assembly of the UN).
The term "charter" is used for particularly
formal and solemn instruments, such as the constituent treaty of an international
organization. The term itself has an emotive content that goes back to the Magna Carta of
1215. Well-known recent examples are the Charter of the United Nations of 1945 and the
Charter of the Organization of American States of 1952.
The term "protocol" is used for agreements less
formal than those entitled "treaty" or "convention". The term could be
used to cover the following kinds of instruments:
(a) A Protocol of Signature is an instrument subsidiary to
a treaty, and drawn up by the same parties. Such a Protocol deals with ancillary matters
such as the interpretation of particular clauses of the treaty, those formal clauses not
inserted in the treaty, or the regulation of technical matters. Ratification of the treaty
will normally ipso facto involve ratification of such a Protocol.
(b) An Optional Protocol to a Treaty is an instrument that
establishes additional rights and obligations to a treaty. It is usually adopted on the
same day, but is of independent character and subject to independent ratification. Such
protocols enable certain parties of the treaty to establish among themselves a framework
of obligations which reach further than the general treaty and to which not all parties of
the general treaty consent, creating a "two-tier system". The Optional Protocol
to the International Covenant on Civil and Political Rights of 1966 is a well-known
(c) A Protocol based on a Framework Treaty is an instrument
with specific substantive obligations that implements the general objectives of a previous
framework or umbrella convention. Such protocols ensure a more simplified and accelerated
treaty-making process and have been used particularly in the field of international
environmental law. An example is the 1987 Montreal Protocol on Substances that Deplete the
Ozone Layer adopted on the basis of Arts.2 and 8 of the 1985 Vienna Convention for the
Protection of the Ozone Layer.
(d) A Protocol to amend is an instrument that contains
provisions that amend one or various former treaties, such as the Protocol of 1946
amending the Agreements, Conventions and Protocols on Narcotic Drugs.
(e) A Protocol as a supplementary treaty is an instrument
which contains supplementary provisions to a previous treaty, e.g. the 1967 Protocol
relating to the Status of Refugees to the 1951 Convention relating to the Status of
(f) A Proces-Verbal is an instrument that contains a record
of certain understandings arrived at by the contracting parties.
The term "declaration" is used for various
international instruments. However, declarations are not always legally binding. The term
is often deliberately chosen to indicate that the parties do not intend to create binding
obligations but merely want to declare certain aspirations. An example is the 1992 Rio
Declaration. Declarations can however also be treaties in the generic sense intended to be
binding at international law. It is therefore necessary to establish in each individual
case whether the parties intended to create binding obligations. Ascertaining the
intention of the parties can often be a difficult task. Some instruments entitled
"declarations" were not originally intended to have binding force, but their
provisions may have reflected customary international law or may have gained binding
character as customary law at a later stage. Such was the case with the 1948 Universal
Declaration of Human Rights. Declarations that are intended to have binding effects could
be classified as follows:
(a) A declaration can be a treaty in the proper sense. A
significant example is the Joint Declaration between the United Kingdom and China on the
Question of Hong Kong of 1984.
(b) An interpretative declaration is an instrument that is
annexed to a treaty with the goal of interpreting or explaining the provisions of the
(c) A declaration can also be an informal agreement with
respect to a matter of minor importance.
(d) A series of unilateral declarations can constitute
binding agreements. A typical example are declarations under the Optional Clause of the
Statute of the International Court of Justice that create legal bonds between the
declarants, although not directly addressed to each other. Another example is the
unilateral Declaration on the Suez Canal and the arrangements for its operation issued by
Egypt in 1957 which was considered to be an engagement of an international character.
Memoranda of Understanding
A memorandum of understanding is an international
instrument of a less formal kind. It often sets out operational arrangements under a
framework international agreement. It is also used for the regulation of technical or
detailed matters. It is typically in the form of a single instrument and does not require
ratification. They are entered into either by States or International Organizations. The
United Nations usually concludes memoranda of understanding with Member States in order to
organize its peacekeeping operations or to arrange UN Conferences. The United Nations also
concludes memoranda of understanding on co-operation with other international
A modus vivendi is an instrument recording an international
agreement of temporary or provisional nature intended to be replaced by an arrangement of
a more permanent and detailed character. It is usually made in an informal way, and never
Exchange of Notes
An "exchange of notes" is a record of a routine
agreement, that has many similarities with the private law contract. The agreement
consists of the exchange of two documents, each of the parties being in the possession of
the one signed by the representative of the other. Under the usual procedure, the
accepting State repeats the text of the offering State to record its assent. The
signatories of the letters may be government Ministers, diplomats or departamental heads.
The technique of exchange of notes is frequently resorted to, either because of its speedy
procedure, or, sometimes, to avoid the process of legislative approval.
Terms Relating to Treaty