The chapter analyses each element of the definition of a treaty in the Vienna Convention on the Law of Treaties 1969: an international agreement, concluded between states, in written form, governed by international law, either in a single instrument or in two or more related instruments, whatever its particular designation. Agreements in simplified form such as an exchange of notes or an exchange of letters can also be treaties. The chapter examines the criteria which international courts and tribunals have applied in determining whether other instruments such as agreed minutes might constitute treaties. Relevant factors include: form and designation, terminology, subject matter, terms, context, intent, level of negotiator, definite or conditional terms, clarity, subsequent practice, and registration with the UN. Examples of electronic signature are noted, although state practice is sparse. A treaty should be distinguished from a non-legally binding instrument, such as a memorandum of understanding, although some states use the title ‘Memorandum of Understanding’ also for treaties with a certain subject matter. Unilateral declarations are not treaties but may in some circumstances have binding legal effects. Treaties have a wide variety of titles, including Protocol, but the title does not itself determine whether an instrument is a treaty.

The Oslo Accords were signed between Israel and the Palestine Liberation Organisation (PLO) granting the Palestinians elements of self-government for an interim period leading to negotiations on the final status of the West bank and Gaza. The Accords have been subject to intense criticism. However, for the first time the Arab Palestinians had their own, freely elected, administration, albeit subject to restrictions. The word autonomy, implying that the area is part of an existing State, was used in the 1978 Camp David Accords but was omitted from the Oslo Accords. Jerusalem and Israel settlements were excluded from the jurisdiction of the Palestinian Authority but it was agreed that their status would be part of the negotiations on the final status of the West Bank. The Accords had very broad international support and, although there are mutual claims that the Accords have been violated, neither part has formally abrogated them.