Accession and Acceptance are two methods by which a State may express its consent to be bound by an international treaty. Both are recognised under the Vienna Convention on the Law of Treaties, 1969 (VCLT), but they operate in different circumstances. Accession is particularly important for a State that did not sign a treaty, while acceptance is generally an alternative to ratification where the treaty or the circumstances permit it.
- Accession
- Nature of Accession
- Instrument of Accession
- Accession and Signature
- Accession and Ratification
- Acceptance and Ratification
- Acceptance and Approval
- Acceptance in Multilateral Treaties
- Instrument of Acceptance
- Acceptance Without Ratification
- Accession vs Acceptance
- Accession vs Ratification
- Acceptance vs Ratification
- Accession and Reservations
- Accession and Entry into Force
- Deposit of Instrument
- Article 18 and Accession
- Article 24 and Entry into Force
- Accession and Multilateral Treaties
- Important VCLT Provisions
- Simple Example
- Quick Revision
- Conclusion
Accession
Accession is the formal act by which a State expresses its consent to be bound by a treaty after the treaty has been concluded, particularly where that State did not sign the treaty during the period when it was open for signature.
Under Article 15 VCLT, consent to be bound is expressed by accession where:
- the treaty provides that consent may be expressed by accession;
- it is otherwise established that the negotiating States agreed that consent could be expressed by accession; or
- all parties subsequently agree that consent may be expressed by accession.
Nature of Accession
Accession is especially relevant to multilateral treaties.
The basic process is:
Treaty adopted
↓
Treaty open for signature
↓
State does not sign
↓
Treaty permits accession
↓
State deposits instrument of accession
↓
State becomes bound according to the treaty
Thus, accession allows a State to join a treaty without having previously signed it.
Instrument of Accession
A State normally expresses accession through an instrument of accession.
For a multilateral treaty, the instrument is generally deposited with the designated depositary.
The depositary may be:
- a State;
- an international organisation;
- an official of an international organisation.
Accession and Signature
The principal difference is:
Signature
→ normally occurs while the treaty is open for signature.
Accession
→ allows a State to become a party without having signed the treaty during that period.
Therefore:
Accession is a method of expressing consent to be bound without prior signature.
Accession and Ratification
Accession should also be distinguished from ratification.
Ratification
Usually follows signature where the treaty has been signed subject to ratification.
Accession
Usually applies where the State did not sign the treaty and subsequently joins it through the procedure provided by the treaty.
Therefore:
Signed → Ratification
Not signed → Accession
This is a useful examination distinction, although the precise treaty provisions must always be examined.
Acceptance
Acceptance is a method of expressing consent to be bound by a treaty.
Under Article 14 VCLT, consent to be bound is expressed by acceptance where:
- the treaty provides that consent may be expressed by acceptance;
- it is otherwise established that the negotiating States agreed that consent could be expressed by acceptance; or
- the State’s intention to accept the treaty appears from its representative’s full powers or was expressed during negotiations.
Acceptance therefore performs a function similar to ratification in circumstances where the treaty provides for acceptance.
Acceptance and Ratification
Acceptance is not necessarily a different level of commitment from ratification.
Both can serve as methods of expressing a State’s consent to be bound.
The difference primarily concerns the procedure specified or permitted by the treaty.
Ratification → formal confirmation of consent
Acceptance → alternative method of expressing consent
Acceptance and Approval
The VCLT treats acceptance and approval alongside ratification in Article 14.
They may be used where the treaty or the negotiating States provide for these methods.
The legal effect is generally to establish the State’s consent to be bound.
Acceptance in Multilateral Treaties
Acceptance is commonly encountered in multilateral treaty practice.
A simplified process is:
Negotiation
↓
Adoption
↓
Signature or other agreed procedure
↓
Acceptance
↓
Deposit of instrument
↓
Entry into force
The exact process depends upon the treaty.
Instrument of Acceptance
A State normally communicates its acceptance through an instrument of acceptance.
For a multilateral treaty, this instrument is generally deposited with the treaty’s depositary.
Acceptance Without Ratification
Where a treaty permits acceptance as a method of expressing consent, a State may use acceptance rather than ratification.
Thus:
Treaty permits acceptance
↓
State chooses acceptance
↓
Instrument of acceptance deposited
↓
Consent to be bound established
subject to the treaty’s entry-into-force requirements.
Accession vs Acceptance
| Accession | Acceptance |
|---|---|
| Method of expressing consent to be bound | Method of expressing consent to be bound |
| Particularly relevant to a State that did not sign | May be used instead of ratification where permitted |
| Governed principally by Article 15 VCLT | Governed principally by Article 14 VCLT |
| Often involves joining an existing treaty | Often serves as an alternative to ratification |
| Instrument of accession | Instrument of acceptance |
| Does not require prior signature | May occur in the treaty process according to its terms |
Accession vs Ratification
| Accession | Ratification |
|---|---|
| Generally used by a State that did not sign | Generally follows signature |
| Article 15 VCLT | Article 14 VCLT |
| No prior signature required | Signature normally precedes it |
| Instrument of accession | Instrument of ratification |
| Common in multilateral treaties | Common where treaty requires ratification |
Acceptance vs Ratification
| Acceptance | Ratification |
|---|---|
| Alternative method of consent | Formal method of consent |
| Article 14 VCLT | Article 14 VCLT |
| Used where treaty permits | Used where treaty requires or permits |
| Instrument of acceptance | Instrument of ratification |
| Generally similar legal effect | Generally similar legal effect |
Accession and Reservations
A State acceding to a treaty may formulate a reservation where the treaty and applicable International Law permit it.
Under Article 2(1)(d) VCLT, a reservation seeks to exclude or modify the legal effect of certain treaty provisions in their application to the reserving State.
Reservations are principally governed by Articles 19–23 VCLT.
Therefore:
Accession
Permissible reservation
↓
State becomes bound subject to the reservation
where the reservation is legally valid.
Accession and Entry into Force
Accession does not necessarily mean that the treaty immediately becomes operative for the acceding State.
The treaty may establish particular requirements concerning:
- deposit of the instrument;
- waiting periods;
- number of parties;
- entry-into-force dates.
Therefore:
Accession ≠ necessarily immediate entry into force
Deposit of Instrument
Under Article 16 VCLT, instruments of ratification, acceptance, approval or accession establish consent when exchanged between contracting States or deposited with the depositary, or when otherwise agreed.
For multilateral treaties, deposit with the designated depositary is particularly common.
Article 18 and Accession
The obligation under Article 18 VCLT concerning acts that would defeat the object and purpose of a treaty is particularly associated with States that have:
- signed the treaty subject to ratification, acceptance or approval; or
- expressed consent to be bound but before the treaty enters into force, where the provision applies.
A State that has not signed but is merely considering accession is not in the same position as a signatory State under Article 18.
Article 24 and Entry into Force
Under Article 24 VCLT, a treaty enters into force according to:
- the manner and date provided in the treaty; or
- the agreement of the negotiating States.
Where a treaty does not specify the date, the general VCLT rules apply.
Accession and Multilateral Treaties
Accession is particularly significant for multilateral treaties because treaties may remain open for participation after their initial adoption and signature period.
For example:
Original negotiating States
↓
Treaty adopted
↓
Signature period
↓
Additional State did not sign
↓
Treaty permits accession
↓
Additional State accedes
↓
State becomes a party
Important VCLT Provisions
| Article | Subject |
|---|---|
| Article 11 | Methods of expressing consent to be bound |
| Article 12 | Consent by signature |
| Article 13 | Consent by exchange of instruments |
| Article 14 | Ratification, acceptance or approval |
| Article 15 | Accession |
| Article 16 | Exchange or deposit of instruments |
| Article 17 | Consent to part of a treaty |
| Article 18 | Obligation not to defeat object and purpose |
| Articles 19–23 | Reservations |
| Article 24 | Entry into force |
Simple Example
Suppose a multilateral treaty is concluded by 50 States.
State A signs the treaty
↓
State A later ratifies it
State B does not sign the treaty
↓
The treaty permits accession
↓
State B deposits an instrument of accession
↓
State B becomes bound according to the treaty
Now suppose another State, State C, signs the treaty but the treaty permits acceptance instead of ratification.
State C signs
↓
State C accepts the treaty
↓
Instrument of acceptance deposited
↓
Consent to be bound established
This illustrates the difference between accession and acceptance.
Quick Revision
- Accession → method of expressing consent to be bound by a treaty, especially where a State did not sign it.
- Article 15 VCLT → accession.
- Acceptance → method of expressing consent to be bound where the treaty permits it.
- Article 14 VCLT → ratification, acceptance and approval.
- Instrument of accession → formal document expressing accession.
- Instrument of acceptance → formal document expressing acceptance.
- Accession generally does not require prior signature.
- Ratification generally follows signature.
- Acceptance may operate as an alternative to ratification.
- Article 16 → exchange or deposit of instruments.
- Articles 19–23 → reservations.
- Article 24 → entry into force.
- Accession does not necessarily mean immediate entry into force.
- The easiest distinction is:
Accession allows a State that did not sign a treaty to become bound by it, while acceptance is an alternative method of expressing consent to be bound where the treaty permits it.
Conclusion
Accession and Acceptance are recognised methods through which States express their consent to be bound by international treaties. Accession, governed principally by Article 15 of the Vienna Convention on the Law of Treaties, 1969, is particularly important for States that did not sign a treaty during the period when it was open for signature. Such a State may subsequently become a party by depositing an instrument of accession where the treaty or the parties permit this method. Acceptance, governed by Article 14, is an alternative method of expressing consent to be bound and may operate in circumstances similar to ratification where the treaty provides for it. Both processes require compliance with the treaty’s specific provisions and may involve the deposit of an appropriate instrument with the designated depositary. Accession should therefore be distinguished from ratification: ratification generally follows signature, whereas accession does not require prior signature. Acceptance, on the other hand, is primarily an alternative method of consent alongside ratification and approval. These mechanisms demonstrate the importance of State consent in the Law of Treaties while providing flexible methods through which States can become parties to international agreements.
