Public International Law Notes - The Law of Treaties

PIL: L4 - The Law of Treaties

How are obligations defined:
 …in a state?
- Contracts, agreements under seal, legislation, regulations, judicial decisions
 …in international law?
- Custom – developed over time (state practice + opinio juris)
- Treaties – direct and formal method of lawmaking
 Treaties are the main way that states define their obligations under international law
- Termination of wars
- Acquisition of territory
- Alliance created
- International organizations established
- States withdrawal from IOs (Brexit)

Some key treaties:
 UN Charter (1945)
 UN Framework Convention on Climate Change (1992)
 Geneva Conventions (1949)
 Chemical Weapons Convention (1992)
 Chicago Convention on International Civil Aviation (1944)
 Treaty on the Non-Proliferation of Nuclear Weapons (1966)
 International Convention for the Suppression of the Financing of Terrorism
(1999)
 United Nations Convention on the Law of the Sea (1982)
 Treaty on European Union (1992)

Finding treaties online:
 UN Treaty Series Collection https://treaties.un.org/
 UK Treaties Online (UKTO)
https://treaties.fco.gov.uk/responsive/app/consolidatedSearch/
 EU Treaties Office Database
http://ec.europa.eu/world/agreements/searchByType.do?id=2

Law of Treaties:
 Two main conventions on the law of treaties:
- 1969 Vienna Convention on the Law of Treaties (VCLT):
o Came into force in 1980
o Largely reflects customary international law (developed over time and
customs)
o Applies to treaties between states
o Applies to the constituent treaties of international organizations
- 1986 Vienna Convention on Treaties between States and International
Organizations (VCLT-IO):
o Yet to enter into force- still get used by courts, states but not as a treaty,
because it reflects customary international law
o Reflects customary international law and progressive development of the
law

, o Applies to treaties between states and international organizations + between
international organizations
 Constitute the basic principles of treaty law: interpretation, breach, entry into force,
fundamental change of circumstances

Principles of the law of treaties:
 Without this principle, there would be no treaties – no point
 Principle of pacta sunt servanda “treaties shall be complied with” is a foundational
principle of international law
 Article 26, 1969 VCLT: “Every treaty in force is binding upon the parties to it and
must be performed by them in good faith”

What is a treaty:
 A treaty is “an agreement between parties on the international scene” (Shaw)
 An agreement:
- Between parties (usually states)
- International scene (governed by international law)
 Various names are used: treaty, protocol, act, charter, covenant, pact, constitution
- BUT to determine if it is a treaty, it must satisfy certain elements
 1969 VCLT, Article 2: defines a treaty for the purpose of this convention
“1. For the purposes of the present Convention:
(a) "Treaty" means an international agreement concluded between States in written form
and governed by international law, whether embodied in a single instrument or in two or
more related instruments and whatever its particular designation”
a. international agreement:
- Agreement is required – an element like a contract e.g. cannot be imposed
against the will of a state
- There must be an intention to establish legal relations between the parties
- E.g. a declaration of political aim does not create legal relations
- How to establish intent? Look at the agreement and facts of the situation as a
whole. Does the agreement establish legal relations?
- An instrument is likely to be a treaty if
o It was registered at the United Nations
o It was signed/ratified according to domestic law of that state as a treaty
- A memorandum of understanding (MoU) is a politically important instrument,
but not a treaty under international law
b. Between States:
- Treaties cannot be unilateral – has to be between two or more states
- BUT treaties can be entered into by other subjects of international law. Those
agreements are not governed by the VCLT, however:
- Article 3 VCLT: “The fact that the present Convention does not apply to
international agreements concluded between States and other subjects of
international law or between such other subjects of international law, or to
international agreements not in written form, shall not affect:
(a) The legal force of such agreements;
(b) The application to them of any of the rules set forth in the present
Convention to which they would be subject under international law
independently of the Convention;