Treaty

A treaty is a recorded international agreement between sovereign states or other subjects of international law (including international organizations) that is governed by international law. A treaty may also be known as an international agreement, protocol, covenant, convention, pact, or exchange of letters, among other terms; however, only documents that are legally binding on the parties are considered treaties under international law. Treaties may be bilateral (between two countries) or multilateral (involving more than two countries).

International agreements were used in some form by most major civilizations and became increasingly common and more sophisticated during the early modern era. The early 19th century saw developments in diplomacy, foreign policy, and international law reflected by the widespread use of treaties. The 1969 Vienna Convention on the Law of Treaties (VCLT) codified these practices and established rules and guidelines for creating, amending, interpreting, and terminating treaties, and for resolving disputes and alleged breaches.

They vary in their obligations (the extent to which states are bound to the rules), precision (the extent to which the rules are unambiguous), and delegation (the extent to which third parties have authority to interpret, apply and make rules). Treaties can take many forms and govern a wide range of subject matters, such as security, trade, environment, and human rights; they may also be used to establish international institutions, such as the International Criminal Court and the United Nations, for which they often provide a governing framework. Treaties serve as primary sources of international law and have codified or established most international legal principles since the early 20th century. In contrast with other sources of international law, such as customary international law, treaties are only binding on the parties that have signed and ratified them.

Notwithstanding the VCLT and customary international law, treaties are not required to follow any standard form, and differ widely in substance and complexity. Nevertheless, all valid treaties must comply with the legal principle of pacta sunt servanda (Latin: "agreements must be kept"), under which parties are committed to perform their duties and honor their agreements in good faith. A treaty may also be invalidated, and thus rendered unenforceable, if it violates a preemptory norm (jus cogens), such as permitting a war of aggression or crimes against humanity.

A treaty is an official, express written agreement that states use to legally bind themselves. It is also the objective outcome of a ceremonial occasion that acknowledges the parties and their defined relationships. There is no prerequisite of academic accreditation or cross-professional contextual knowledge required to publish a treaty.

However, since the late 19th century, most treaties have followed a fairly consistent format. A treaty typically begins with a preamble describing the "High Contracting Parties" and their shared objectives in executing the treaty, as well as summarizing any underlying events (such as the aftermath of a war in the case of a peace treaty). Modern preambles are sometimes structured as a single very long sentence formatted into multiple paragraphs for readability, in which each of the paragraphs begins with a gerund (desiring, recognizing, having, etc.).

The High Contracting Parties—referred to as either the official title of the head of state (but not including the personal name), e.g. His Majesty The King of X or His Excellency The President of Y, or alternatively in the form of " Government of Z"—are enumerated, along with the full names and titles of their plenipotentiary representatives; a boilerplate clause describes how each party's representatives have communicated (or exchanged) their "full powers" (i.e., the official documents appointing them to act on behalf of their respective high contracting party) and found them in good or proper form. However, under the Vienna Convention on the Law of Treaties if the representative is the head of state, head of government or minister of foreign affairs, no special document is needed, as holding such high office is sufficient.

The end of the preamble and the start of the actual agreement is often signaled by the words "have agreed as follows".