The Vienna Convention on the Law of Treaties (VCLT) is an international agreement regulating treaties between states. Known as the "treaty on treaties", it establishes comprehensive rules, procedures, and guidelines for how treaties are defined, drafted, amended, interpreted, and generally operated. An international treaty is a written agreement between international law subjects reflecting their consent to the creation, alteration, or termination of their rights and obligations. The VCLT is considered a codification of customary international law and state practice concerning treaties.
The convention was adopted and opened to signature on 23 May 1969, and it entered into force on 27 January 1980. It has been ratified by 116 states as of January 2018. Some non-ratifying parties, such as the United States, have recognized parts of it as a restatement of customary international law.
The VCLT was drafted by the International Law Commission (ILC) of the United Nations, which began work on the convention in 1949. During the 20 years of preparation, several draft versions of the convention and commentaries were prepared by special rapporteurs of the ILC, which included prominent international law scholars James Brierly, Hersch Lauterpacht, Gerald Fitzmaurice, and Humphrey Waldock.
The convention codifies several bedrocks of contemporary international law. It defines a treaty as "an international agreement concluded between states in written form and governed by international law" and affirms that "every state possesses the capacity to conclude treaties." Article 1 restricts the application of the convention to written treaties between States, excluding treaties concluded between the states and international organizations or international organizations themselves. Article 26 defines pacta sunt servanda, Article 53 proclaims peremptory norm, and Article 62 proclaims Fundamental Change of Circumstance.
The Convention applies only to treaties that came after it was made and to those concluded between states and so does not govern agreements between states and international organizations or between international organizations themselves, but if any of its rules are independently binding on such organizations, they remain so. The VCLT applies to treaties between states within an intergovernmental organization.
However, agreements between states and international organizations or between international organizations themselves are governed by the 1986 Vienna Convention on the Law of Treaties between States and International Organizations or Between International Organizations if it enters into force. Furthermore, in treaties between states and international organizations, the terms of the Convention still apply between the state members. The Convention does not apply to unwritten agreements.
When a treaty is open to "States", it may be difficult or impossible for the depositary authority to determine which entities are States. If the treaty is restricted to Members of the United Nations or Parties to the Statute of the International Court of Justice, there is no ambiguity. However, a difficulty has occurred as to possible participation in treaties when entities that appeared otherwise to be States could not be admitted to the United Nations or become Parties to the Statute of the International Court of Justice because of the opposition for political reasons of a permanent member of the Security Council or have not applied for ICJ or UN membership. Since that difficulty did not arise as concerns membership in the specialized agencies, on which there is no "veto" procedure, a number of those States became members of specialized agencies and so were in essence recognized as States by the international community. Accordingly, to allow for as wide a participation as possible, a number of conventions then provided that they were also open for participation to States members of specialized agencies. The type of entry-into-force clause used in the Vienna Convention on the Law of Treaties was later called the "Vienna formula," and its wording was used by various treaties, conventions and organizations.
Articles 31-33 of the VCLT entail principles for interpreting conventions, treaties etc. These principles are recognized as representing customary international law, for example by the International Law Commission (ILC).
On February 6, 1900, the Permanent Court of Arbitration (PCA) was with the ratification of the 1899 Convention for the Pacific Settlement of International Disputes. Set at The Hague in the Netherlands, the PCA was the first international tribunal established to settle disputes between nations. The PCA was later revised by the subsequent 1907 Convention for the Pacific Settlement of International Disputes. Today, the PCA is housed at the Peace Palace in The Hague and is comprised of 109 member-countries.Browse PAC opinions. 2b1af7f3a8