A multilateral treaty is a treaty

Treaty

A treaty is an express agreement under international law entered into by actors in international law, namely sovereign states and international organizations. A treaty may also be known as an agreement, protocol, covenant, convention or exchange of letters, among other terms...

 to which three or more sovereign state

Sovereign state

A sovereign state, or simply, state, is a state with a defined territory on which it exercises internal and external sovereignty, a permanent population, a government, and the capacity to enter into relations with other sovereign states. It is also normally understood to be a state which is neither...

s are parties. Each party owes the same obligations to all other parties, except to the extent that they have stated reservations

Reservation (law)

A reservation in international law is a caveat to a state's acceptance of a treaty. By the 1969 Vienna Convention on the Law of Treaties , a reservation is defined as a...

. Some examples of multilateral treaties are the Convention Relating to the Status of Refugees

Convention Relating to the Status of Refugees

The United Nations Convention Relating to the Status of Refugees is an international convention that defines who is a refugee, and sets out the rights of individuals who are granted asylum and the responsibilities of nations that grant asylum. The Convention also sets out which people do not...

, the United Nations Convention on the Law of the Sea

United Nations Convention on the Law of the Sea

The United Nations Convention on the Law of the Sea , also called the Law of the Sea Convention or the Law of the Sea treaty, is the international agreement that resulted from the third United Nations Conference on the Law of the Sea , which took place from 1973 through 1982...

, the Geneva Conventions

Geneva Conventions

The Geneva Conventions comprise four treaties, and three additional protocols, that establish the standards of international law for the humanitarian treatment of the victims of war...

, and the Rome Statute of the International Criminal Court

Rome Statute of the International Criminal Court

The Rome Statute of the International Criminal Court is the treaty that established the International Criminal Court . It was adopted at a diplomatic conference in Rome on 17 July 1998 and it entered into force on 1 July 2002. As of 13 October 2011, 119 states are party to the statute...

.

Relationship to bilateral treaties

A bilateral treaty

Bilateral treaty

A bilateral treaty is a treaty strictly between two state parties. These two parties can be two states, or two international organizations, or one state and one international organization.It is similar to a contract, so it is called contractual treaty....

 is a treaty between two states. A bilateral treaty may become a multilateral treaty when additional new parties succeed

Succession of states

Succession of states is a theory and practice in international relations regarding the recognition and acceptance of a newly created sovereign state by other states, based on a perceived historical relationship the new state has with a prior state...

 or accede

Ratification

Ratification is a principal's approval of an act of its agent where the agent lacked authority to legally bind the principal. The term applies to private contract law, international treaties, and constitutionals in federations such as the United States and Canada.- Private law :In contract law, the...

 to it.

Plurilateral treaties

A plurilateral treaty is a special type of multilateral treaty. A plurilateral treaty is a treaty between a limited number of states with a particular interest in the subject of the treaty. The primary difference between a plurilateral treaty and other multilateral treaties is that the availability of reservations

Reservation (law)

A reservation in international law is a caveat to a state's acceptance of a treaty. By the 1969 Vienna Convention on the Law of Treaties , a reservation is defined as a...

 is more limited under a plurilateral treaty. Due to the limited nature of a plurilateral treaty treaty, the full cooperation of the parties to the treaty is required in order for the object of the treaty to be met. As a result, reservations to plurilateral treaties are not allowed without the consent of all other parties to the treaty. This principle is codified in international law

International law

Public international law concerns the structure and conduct of sovereign states; analogous entities, such as the Holy See; and intergovernmental organizations. To a lesser degree, international law also may affect multinational corporations and individuals, an impact increasingly evolving beyond...

 by article 20(2) of the Vienna Convention on the Law of Treaties

Vienna Convention on the Law of Treaties

The Vienna Convention on the Law of Treaties is a treaty concerning the international law on treaties between states. It was adopted on 22 May 1969 and opened for signature on 23 May 1969. The Convention entered into force on 27 January 1980. The VCLT has been ratified by 111 states as of November...

:

When it appears from the limited number of the negotiating states and the object and purpose of a treaty that the application of the treaty in its entirety between all the parties is an essential condition of the consent of each one to be bound by the treaty, a reservation requires acceptance by all the parties.

An example of a plurilateral treaty is the Antarctic Treaty.