This is an extract of our Law Of Treaties document, which we sell as part of our Public International Law Notes collection written by the top tier of Oxford students.
The following is a more accessble plain text extract of the PDF sample above, taken from our Public International Law Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:
The Law of Treaties
As pointed out above, treaties are now increasingly becoming one of the most prominent sources of international law. 'The law of treaties' governs the use of such treaties as sources: how are they validly made, how are reservations validly made, how are treaties terminated, etc. The law of treaties, for the most part, is embodied in the Vienna Convention on the Law of Treaties 1969
(VCLT), some part of which codifies existing customary law, and some part of which was intended as 'progressive development', which may later pass into customary law due to state practice caused by their incorporation in the Convention. The most striking example of this category is the law on reservations under Art 19-23, which did not represent customary law at the time VCLT was drafted,
and is still controversial, but its customary status is becoming more certain. This is important because 'progressive development' clauses bind state parties only when and if they crystallise into customary international law. Those areas not governed by VCLT continues to be regulated by customary international law. Three types of treaties can be distinguished: bilateral treaties,
multilateral treaties establishing international institutions/regimes, and 'fundamentally norm creating' multilateral treaties.
Don't forget the relationship between treaty and custom! As explained in the North Sea Continental
Shelf Cases, treaties can:
- be declaratory of existing customary law (codification)
- evolve at the same time as customary law (agreement arises in the course of drafting, and may be implemented in practice before Treaty comes into force)
- later evolve to become part of customary law post hoc.
Art 2 of the VCLT states that it applies to 'international agreements 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'. Also note that VCLT only applies to treaties concluded after VCLT's entering into force.
Agreement must be intended to create legal relations — the intention and consent of parties is important. Although this is not stated in the article, it can be inferred from 'governed by international law' (apparently, per ILC). Absence of a common intention to create such rights and obligations is fatal to finding an enforceable agreement (Aegean Sea Continental Shelf Case). A
useful but not conclusive indicator as to whether an agreement is a treaty is whether it is registered with the UN as such. 'Whatever its particular designation' also goes to intention, as it means what label is given to the agreement does not matter, so long it is objectively understood as a treaty, with reference to the intention of the parties. States commonly draft documents which are intended as only political commitments, and not legally binding (usually called Memorandum of
Understanding), but whether such documents are legally binding or are actually political commitments is an objective question to be answered with reference to circumstantial evidence/text/
terms etc. 'Between states' (Art 1) excludes from the scope of VCLT agreements concluded between Stateother subjects or other subjects-other subjects (such as international organisations). But see Article 3, which is sort of a saving clause, which states that the Article 2(1)(a) definition of a treaty does not affect the legal force of an international agreement or the application of any rules of the VCLT
which would apply independently of it at customary international law. There is a separate 1986
Convention on the Law of Treaties between States and International Organisations or between International Organisations which regulates the treaties to which int'l organisations are party to. Individuals and legal persons under national law (ie companies) do not have the capacity to make treaties, either with states or international organisations: in the Anglo-Iranian Oil Company case, the ICJ rejected the argument that the contract between the British Anglo-Iranian Oil
Company and Iran was a treaty (even tho UK gov had played part in negotiations); it was held to merely be a contract between the Iranian government and a foreign company.
The rules for creation of treaties are found in Part II of VCLT. The question of who has the authority to conclude international treaties on behalf of a State is a matter for national law: the head of state, head of government and the minister of foreign affairs always have authority (Art 7).
The legal effect of treaties/scope of the legal obligation is that it is binding on parties, and must be performed by them in good faith (Art 26 — pacta sunt servanda). Treaties are binding only on the States party to them. However, third states can be bound if they so consent (Art 34), or can be conferred rights (Art 35). 'Dispositive' treaties are those which, by their nature, have to be respected by non-party states (eg: China-UK secession treaty for HK; no state can claim that UK is the sovereign of HK anymore) — the legal regimes are valid for the whole world.
In order for a treaty to be legally binding, two criteria must be met: 1) state's consent to be bound,
and 2) treaty's entry into force. Signature is generally not sufficient to indicate consent to be bound,
but obligation not to act inconsistent with the object and purpose of the treaty. Signatures generally subject to ratification (but if treaty itself says signature is sufficient to make it binding, it will be).
Once a treaty enters into force, it is fully binding. Entry into force will usually require a certain number of ratifications.
Treaties are legally binding once they have been ratified + entered into force. States who have signed but not yet ratified a treaty, have more limited obligations under Art 18, which is only to
'refrain from acts which would defeat the object and purpose of a treaty' (this also applies to any state that has expressed consent to be bound during the period leading up to the entry of force of the treaty). (But NB other circumstances which may give rise to legally binding obligations: sometimes unilateral acts/statements, legally binding acts in national law … )
Part II gives primacy to terms of each treaty in determining what rules apply to its inception as legally binding. But NB lil paradox: rules in a treaty relating to its own entry into force etc are not legally binding because the treaty in which they are contained will not have yet entered into force
Buy the full version of these notes or essay plans and more in our Public International Law Notes.