Vienna Convention on Law of Treaties (VCLT)

Heart of Treaty law : VCLT
• Vienna Convention on Law of Treaties (VCLT), 1969

– ILC started to work on 1949 (worked for 20 years)

– signed at Vienna on 23 May 1969

– entered into force on 27 January 1980 after being ratified by 35 States

• Nepal:

signed the treaty on 23 May 1969

– But has not ratified yet

• Till date, 114 parties; 45 signatories

• Treaty on Treaties

• Main instrument to regulate treaties

– Defines terms

– Relates to how treaties are made, amended, interpreted, operated and terminated

– Does not provide substantive provision (to be provided by specific treaty UNCLOS)

Preamble provides

– “the rules of CIL will continue to govern questions not regulated by the provisions of the present Convention”.

• VCLT 1969

– only deals with treaty between states

• 1986 there was another Vienna Convention on Law of treaties between state and IO or between IOs – But it has not been into force yet .

• covers traditional topics but not exhaustive

• General Law or Progressive Development?

• Sinclair – A glance at VCLT reveals that

• it covers all the topics traditionally regarded as falling within the framework of the law of treaties

– that is to say, the conclusion and entry into force of treaties

• The Convention in addition lays down procedural rules concerning depositaries, notifications, corrections and registration.
• VCLT does not regulate all legal issues involving treaties.

• does not cover questions of performance of treaty obligations or responsibility for breaches of such obligations. – Such question governed by CIL (Art. On State Responsibility)

• Does not deal State succession of treaties

• Does not deal Effect of Armed conflict on treaties

VCLT > should state be party ?
Gabčíkovo-Nagymaros Project (Hungary v. Slovakia, 1997)

– “[The Court] needs only to be mindful of the fact that it has several times had occasion to hold that some of the rules laid down in that Convention might be considered as a codification of existing customary law”

– The Court’s opinion, together with the relatively high number of parties to the Convention, suggests that the instrument states the current general international law of treaties.

– This is also confirmed by the fact that its substantive provisions were by consensus copied into the 1986 Vienna Convention on the Law of Treaties between States and IO or between IOs.


– ICJ, Legal Consequences for States of the Continued Presence of South Africa in Namibia, 1971

– ICJ, Fisheries Jurisdiction Case (UK v. Iceland), 1973 – ECtJ, Opel Austria v. Council of EU (1997) – WTO, US—Gasoline, 1996; US – Gambling, 2005

• Recognized importance of treaty

– As a source of int’l law

– Means of developing peaceful cooperation among nations

• Noted the universally recognized principles

– Free consent

– Good faith

Pacta sunt servanda

• Affirmed that dispute to be settled by peaceful means

• Minded, the principle of international law

– equal rights, self determination of people, sovereign equality, noninterference in domestic affairs, prohibition of use of force, observance of human rights and fundamental freedom

• Believed that codification and progressive development of the law of treaties in present convention will promote purpose of UN

– maintenance of peace and security

• Affirmed that CIL will continue to govern questions not regulated by VCLT.

VCLT – Broadly
• (a) the requirements for the valid conclusion of a treaty;

• (b) the identification of the parties to the treaty and the determination of which obligations are binding upon which of those parties;

• (c) the application and interpretation of the treaty;

• (d) the grounds for terminating the treaty.
• “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

– VCLT article 2(1)(a)

• (1) International agreement concluded between States governed by international law

• (2) Written agreements embodied in a single instrument or in two or more related instruments

• (3) Whatever its particular designation
International agreement concluded between States governed by international law

• VCLT, principally applicable to state party

– Relates that, ‘treaty’ must be concluded between state who are party to VCLT

– However, provision of VCLT if it reflect CIL, need not be party to VCLT for application of that provision

• Eg: Kasikili/Sedudu Island Case, ICJ, 1999 – ICJ held that art 31 of VCLT on treaty interpretation reflected CIL and therefore applied despite the fact that both Botswana and Namibia were not parties to VCLT.

• Gabčíkovo-Nagymaros Project (Hungary v. Slovakia, 1997)
• VCLT applied to treaties between states – Cannot treaties be concluded between other subjects ? – ILC commentaries.

• The articles is not in anyway intended to deny that other subjects of int’l law, such as IO and insurgent communities, may conclude treaties.

• The present convention applies to any treaty which is a constituent instrument of an IO and to an treaty adopted within an IO.
• Governed by international law

– Serves to distinguish between int’l agreements regulated by public international law

– and those which, although concluded between states, are regulated by national law of one party (or other national law system chosen by the parties)

– ILC discussed to add “intention to create an obligation under international law”

– But later concluded that ‘governed by int’l law’ will give the intention
Written agreements embodied in a single instrument or in two or more related instruments

• Written agreement ! – Focus on written – for clarity and simplicity – ILC Clarification

• “written” does not mean that oral agreements under international law have no legal force

• or that the substance of the VCLT articles may not be relevant to them

• it merely means that they are not dealt under the VCLT. – Relevant customary law provisions of the VCLT continue to apply to all treaties, regardless of whether it is codified or not.
• VCLT art 3 – The fact that the present Convention does not apply to (…) or to international agreements not in written form, shall not affect:

• (a) The legal force of such agreements;  Single or two/more related instrument
• Classical form : single treaty

• Modern : more than one instrument – Exchange of notes

Whatever its particular designation
• Convention (1982 UNCLOS) • Treaty (e.g. of peace, extradition, etc.) • Agreement (e.g. cultural cooperation) • Exchange of Notes (Cameroon v Nigeria, ICJ, 10 October 2002) • Protocols (to ICCPR; Kyoto Protocol to 1992 FCCC) • Charter (e.g. UN Charter)

The fine line of separation
• With any other document – to constitute the doc as treaty

• a question of an intention to create legal relations. • The ICJ has interpreted even informal written instruments (such as the minutes of a meeting) as a treaty in the presence of a clear mutual intent.
• Rejected in – Bangladesh vs Myanmar, (Int’l Tribunal for the Law of Sea), 2012

• For legally binding agreement – the substance of the minutes – he circumstances surrounding the adoption – the authority to conclude a legally binding agreement

– internal acceptance as a treaty

• Accepted in – (Qatar vs Bahrain), ICJ, 1994

• “…international agreements may take a number of forms and be given a diversity of names”; i.e the fact that this is called “minutes of meeting”, in itself, does not deny it of its character as a treaty under Article 2(1) (a) of the VCLT.
VCLT – Major issues addressed.

• Art. 3

– Int’l agreement not within the scope of VCLT

– Between states and IO or between IO

– Not in written form

– But VCLT shall not affect legal force/application of such agreement

• Art 4 – Non-retroactivity of the present convention – Applies only to convention concluded by states after the force of VCLT