 This lesson is about treaties, that is, international conventions as article 38 of the ICJ Statutes puts it. Treaties have existed for thousands of years in the history of mankind. They are a very old instrument of international law. For the public opinion, treaties are often associated with international politics and diplomacy. When children learn the names and the dates of important peace treaties that have shaped the history of their country. Intuitively, everybody understands what a treaty is. It is an agreement on the international stage. Conceptually, a treaty is very similar to a contract, but at the international level. There are thousands of treaties, of international treaties, currently binding between two or more states, and also between states and international organizations, or between international organizations. And those thousands of treaties are about many different things. They can be about land or maritime borders, about trade, about international aviation, the promotion or protection of investments, the protection of human rights, or the protection of the environment and biodiversity, the rules of war, judicial cooperation between states and extradition, about disarmament and so on. They can also be treaties establishing international organizations, like the United Nations, the African Union, or the European Union, the World Trade Organization or the International Criminal Court, etc. Actually, any topic, any issue, can be the object of a treaty, provided that there is agreement for that purpose. Well, this lesson will not report on the rules and obligations contained in all those different treaties. This would simply be impossible. Rather, this lesson is about making of treaties in general. It is about the rules of international law relating to the making of any treaty. And in that regard, we are very much helped by the fact that there is a treaty on the law of treaties. It is called the Vienna Convention on the Law of Treaties. It was signed in Vienna on the 23rd of May 1969, and it entered into force on 27 January 1980. 114 states are now currently parties to that treaty, and it is applicable to the treaties contracted by those states after they became bound by it. However, because most of its core provisions reflect customer international law, the substantive rules contained in the Vienna Convention also governs treaties contracted by states that are not party to it. Those substantive rules are not applicable to those treaties as rules of the Vienna Convention, but as rules of customer international law. And for the same reason, those substantive rules also govern treaties concluded by states before they became party to the Vienna Convention. For instance, and as the ICJ has decided on several occasions, the rules on treaty interpretation enshrined in the Vienna Convention may serve for the interpretation of treaties concluded back in the 19th century, because those rules are customary rules written down in the Vienna Convention. According to its article 2, the Vienna Convention applies to an international agreement concluded between states. So from a formal point of view, the Vienna Convention of 1969 does not govern treaties when one of the parties to it is an international organization. Another Vienna Convention signed this time in 1986 was negotiated for the purpose of governing treaties concluded between states and one or several international organizations or between international organizations. However, lacking the needed number of ratifications, that latter convention has not yet entered into force. But this does not mean that international organizations may not conclude treaties, nor that those treaties are governed by rules that are very different from the ones applicable to treaties between states. As a matter of fact, the 1986 Vienna Convention is to a large extent a cut and paste of the 1969 Vienna Convention. And because, as I just mentioned, the 1969 Convention very much reflects customary international law, the same core rules apply to any treaty whether or not international organizations are parties to it. From now on, and as a matter of convenience, I shall most of the time simply refer to the Vienna Convention, meaning the 1969 Vienna Convention on the treaties between states. And for the purpose of the Vienna Convention, a treaty is an, I quote, international agreement concluded in written form and governed by international law, whether embodied in a single instrument or in two or more related instrument and whatever its particular designation, end of quote. In other words, treaties can be finalized in one single document, or be the result of the exchange of several diplomatic notes or texts. Moreover, a treaty is a treaty whatever its name. It can be called treaty, convention, pact, charter, covenant, protocol, memorandum of understanding, statute, whatever. International law is not a formalistic legal order. What matters is the wine in the bottle, not the bottle nor its label. What matters is the existence of an agreement between subjects of international law and an agreement which is governed by international law as opposed to a contract, governed by domestic law, or as opposed to a political agreement which is also called a gentleman's agreement and which is on purpose, not binding under international law and therefore not governed by international law. So it is important to keep in mind that not every agreement between states is a treaty. Only those agreements that parties tacitly or expressly agree to submit to international law are treaties. Let me end this introduction to the notion of treaty by mentioning the fundamental rule of treaty law. It is an easy and straightforward rule, so fundamental that it is intrinsic in any legal system. It is considered to be a basic principle of international law and an essential rule of customary international law. In Latin, that rule is called pactasun servanda, which literally means agreements must be kept. Article 26 of the Vienna Convention is entitled pactasun servanda, and it reads as follows. Every treaty in force is binding upon the parties to it and must be performed by them in good faith." In the next sections of this lesson, we'll learn about the four usual successive steps in the making of treaties, negotiations, signature, ratification and registration of treaties.