Treaties, COP decisions and unilateral declarations

Legal assistance paper

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Date produced: 05/02/2010

Can you provide clarification on the legal status, legal strength (in terms of bindingness) and implications thereof of three different instruments: COP decisions, legally binding treaties and unilateral declarations?

Treaties, COP decisions and unilateral decisions can all be legally binding under international law. Whether or not they are in a particular instance will depend on the facts and the intentions of the parties that are subject to these instruments.

Once it is determined whether any of these are legally binding in a particular instance, their legal status, legal strength and the implications thereof will depend on the conditions attached to them at the time they are agreed to. In other words, the legal form of the obligations will not determine their strength or their implications: these will be determined by the language of the obligations themselves.

In light of the above, in the following paragraphs, I set out how legally binding obligations are created by way of treaty, COP decision and unilateral declaration.


The term “treaty” has regularly been used as a generic term embracing all instruments binding at international law concluded between international entities, regardless of their formal designation. Both the 1969 Vienna Convention and the 1986 Vienna Convention confirm this generic use of the term “treaty”.

The 1969 Vienna Convention defines a treaty as “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”. The 1986 Vienna Convention extends the definition of treaties to include international agreements involving international organizations as parties.

In order to speak of a “treaty” in the generic sense, an instrument has to meet various criteria. First of all, it has to be a binding instrument, which means that the contracting parties intended to create legal rights and duties. Secondly, the instrument must be concluded by states or international organizations with treaty-making power. Thirdly, it has to be governed by international law. Finally the engagement has to be in writing. Even before the 1969 Vienna Convention on the Law of Treaties, the word “treaty” in its generic sense had been generally reserved for engagements concluded in written form. If all these criteria are met, those states and international organisations, that have agreed and ratified that treaty will be bound by it under international law.

COP decisions

Whether or not a COP decision is legally binding on states is dependent in large part on the enabling clause of the treaty under which it is made, i.e. the powers ascribed to the COP in the treaty text and on the language used in the decision itself. Therefore, where the treaty authorises the COP to take action (either generally or specifically), then provided the subject matter of the COP decision falls within the grant of authority to the COP by the treaty and is intended to be legally binding, then the COP decision will be legally binding on the parties.

Article 7.2 of the UNFCCC provides that the: “COP… shall make, within its mandate, the decisions necessary to promote the effective implementation of the Convention”, and it shall to this end “[m]ake recommendations on any matters necessary for the implementation of the Convention” (Art.7.2(g)).

So, for example, if there are reasonable grounds for considering that the objective of the Convention might not be achieved, then it appears that the COP has the authority – indeed, is bound – inter alia to make recommendations in that respect. However it does not follow that a COP decision – as opposed to a Convention amendment or protocol, or a new treaty – imposes an obligation on States (for example) to make specific emission reductions or financial commitments. Further analysis of the specific text and circumstances of its adoption would be required to determine the legal status of such a decision but it certainly cannot be assumed that such a decision would give rise to legal obligations.

Under Article 9.1 of the Kyoto Protocol, the CMP must periodically review the Kyoto Protocol, and based on these reviews the CMP “shall take appropriate action”. Again the status of any text adopted on this basis would have to be analysed specifically but it cannot be assumed that such a text would be legally binding.

The Kyoto Protocol has numerous provisions that require the CMP to take specific action with respect to rule-making. By way of example – Article 3.4 of the Kyoto Protocol reads: “[CMP] shall… decide rules as to which…additional human induced activities and land use change and forestry categories… shall be added to the assigned amounts for Annex 1 Parties”. On the basis of this language there appear to be strong arguments that a CMP decision to add a forestry category would be binding.

Article 7.2 of the Convention provides that: “[the] COP…shall make, within its mandate, the decisions necessary to promote the effective implementation of the Convention.” But it does not go on to say what kind of decisions are necessary, and so the legal status of any such decision must be analysed in part by reference to whether the particular decision under discussion is based on a commitment already in the Convention (i.e. will be “necessary to promote the effective implementation”), or whether it is an entirely new kind of obligation.

Therefore, by way of example – the setting of targets for emissions reductions is unlikely to be legally binding if done by way of COP decision rather than a treaty (or protocol) provision. As another example, it is unlikely that financial commitments would be accepted as legally binding if only made in a COP decision, so a treaty (or protocol) provision is more likely to be enforceable.

Unilateral declarations

It is not possible to offer definitive general advice in general terms on the legal effect of unilateral declarations (or declarations made on behalf of more than one state) – all the circumstances, including the language used, the political level of the official making the statement, the treaty context and the response of other states are relevant to a determination of legal effect.

However, by applying the criteria set out below it is possible to reach a provisional view as to whether it is likely or not that a declaration will have legal effects on the rights and obligations of other states. It is worth noting that most if not all of the cases where unilateral declarations have been held to be binding have not involved multilateral treaty negotiations and are more likely to involve bilateral disputes between two states, eg over diplomatic immunity, over boundaries, or over compensation for harm to a citizen or company’s rights. 

A leading commentator has summarised the position as follows:

There is no settled rule for determining which unilateral declarations give rise to legal rights and duties for other states, and which do not. In some cases the fact that particular consequences flow from a declaration is the result of a treaty provision or a rule of customary international law. Apart from such cases, the question whether any particular declaration directly confers rights or imposes obligations on other states will in the first place largely depend upon the intentions of the state making the declaration and the circumstances of any reliance placed on the declaration by other states.”

There are a number of key points to draw from this:

  • As with the question of whether an instrument or text constitutes a treaty the intention of the state making the declaration is of key importance – making the declaration will not in itself be evidence of an intention to be legally bound by it;
  • It will be necessary to consider the statement in the light of relevant principles of customary international law (if any);
  • It will be necessary to consider whether other states have acted in reliance on the declaration.

The leading case on the status of unilateral declarations is the ICJ’s judgment in the 1974 Nuclear Tests Cases where the Court held that:

  • When it is the intention of the State making the declaration that it should become bound by it according to its terms, that intention confers on the declaration the character of a legal undertaking;
  • An undertaking of this kind, if given publicly and with an intent to be bound, even though not made in the context of international negotiations, is binding;
  • In these cases nothing in the nature of a quid pro quo or reply or reaction is required from other States for the declaration to take effect;
  • The form of the statement itself is not decisive
  • One of the basic principles governing the creation and performance of legal obligations, whatever their source is good faith;

Also relevant in this regard are the “Guiding Principles applicable to unilateral declarations of States capable of creating legal obligations” which were taken note of by the UN General Assembly in December 2006 (Guiding Principles) that provide guidance on when a unilateral statement by a State or State official may be legally binding under international law.  The Principles apply only to formal declarations formulated by a State with the intent to produce obligations under international law. In particular:

Principle 1 provides that:

“Declarations publicly made and manifesting the will to be bound may have the effect of creating legal obligations. When the conditions for this are met, the binding character of such declarations is based on good faith; States concerned may then take them into consideration and rely on them; such States are entitled to require that such obligations be respected”

Principle 7 makes clear that “a unilateral declaration entails obligations for the formulating State only if it is stated in clear and specific terms”. Principle 10 contains rules against unilateral revocation of statements, when there has been reliance by those to whom the obligations are owed.

Often unilateral declarations by States in international negotiations are to excuse themselves from performance, rather than to commit to performance. Declarations under the ICJ Optional Protocol are a very important example to the contrary, of States voluntarily agreeing an additional commitment. Article 36 (2) of the Statute of the ICJ provides that States may declare that they recognise as compulsory and without special agreement the jurisdiction of the court in legal disputes in given circumstances.  Over 60 of the 192 States that are signatory to the Statute have filed unilateral declarations with the UN Secretary General of accepting jurisdiction. There are some detailed rules within the Statute about these declarations, and whether they are made unconditionally or with reciprocity.The key point about the Optional Clause is that the unilateral declarations clearly have binding effect because the Statute itself anticipates that effect.

Given the criteria laid down in the case-law of the ICJ and set out in the Guiding Principles, it would be quite easy for a state to avoid creating legally binding obligations when making a unilateral declaration, but harder to ensure that that legally binding obligations are created.

Also of importance in the context of legally binding unilateral declarations is principle 10 of the Guiding Principles which states that once given, unilateral declarations cannot be revoked following reliance by other parties. This contrasts significantly with, for example article 25 of the UNFCCC and article 27 of the Kyoto Protocol, both of which allow for unilateral withdrawal from obligations one year after notifying the UN Depositary.