3. The law of treaties

Abstract

This chapter examines the rules of international law governing the birth, the life, and the death of treaties. Treaties, a formal source of international law, are agreements in written form between States or international organizations that are subject to international law. A treaty falls under the definition of the Vienna Convention on the Law of Treaties (VCLT), no matter what form or title it may have. The most important factor is that it sets out obligations or entitlements under international law. The VCLT enumerates the rules governing the ‘birth’, ie the steps from the negotiation until the entry into force of the treaty; the ‘life’, ie the interpretation and application of the treaty; and its ‘demise’, ie its termination. The two fundamental tenets are, on the one hand, the principle ‘pacta sunt servanda’ and, on the other, the principle of contractual freedom of the parties.