Legal Bindingness of Unilateral Declarations and Statements

Legal assistance paper

All reasonable efforts have been made to ensure the accuracy of this information at the time the advice was produced (please refer to the date produced below). However, the materials have been prepared for informational purposes only and may have been superseded by more recent developments. They do not constitute formal legal advice or create a lawyer-client relationship. You should seek legal advice to take account of your own interests. To the extent permitted any liability is excluded. Those consulting the database may wish to contact LRI for clarifications and an updated analysis.

Date produced: 09/12/2011

What is the legal bindingness of statements or declarations made in the context of the UNFCCC negotiations by a state official?


Unilateral declarations and COP decisions can 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.

Generally, with respect to a unilateral declaration or statement, the intention of the party, state or official making it is relevant. There must be an intention to be bound. Also relevant is the issue of reliance, i.e. whether any other party or state has relied on the unilateral declaration or statement. Finally, the context of the unilateral declaration or statement may affect whether it is legally binding or not.

In light of the above, the following paragraphs set out how legally binding obligations are created by way of unilateral declaration or statement .


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) or statements – all the circumstances, including the language used, the political level of the official making the declaration or 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 or statement will have a legal effect 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, e.g. 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.[1]

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

The leading case on the status of unilateral declarations is the International Court of Justice’s (ICJ) judgment in the 1974 Nuclear Tests Cases[2] where the ICJ held that:

  • when it is the intention of the state making the declaration or statement that it should become bound by it according to its terms, that intention confers on the declaration or statement 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 or statement to take effect;
  • the form of the declaration or statement itself is not decisive; and
  • one of the basic principles governing the creation and performance of legal obligations, whatever their source is good faith;

It follows that in some circumstances interested states may place confidence in unilateral declarations and are entitled to require that the obligation thus created be respected.

Also relevant in this regard are the “Guiding Principles Applicable to Unilateral Declarations of States Capable of Creating Legal Obligations” (Guiding Principles), which were taken note of by the UN General Assembly in December 2006[3]. These provide guidance on when a unilateral statement by a state or state official may be legally binding under international law. The Guiding 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 declarations or statements, when there has been reliance by those to whom the obligations are owed.

Often unilateral declarations or statements by states in international negotiations are intended to excuse themselves from performance of an obligation, rather than to commit to performance. Declarations under the ICJ Optional Protocol are, however, a very important contrasting example of states voluntarily agreeing to an additional commitment[4]. The key point about the Optional Protocol is that the unilateral declarations of states clearly have binding effect because the ICJ 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.

It is also important to note that principle 10 of the Guiding Principles provides that once given, unilateral declarations or statements cannot be revoked once replied upon by other parties.

[1] Oppenheim’s International Law, Vol 1, Ninth Edition 1996, at page 1190 and see the notes therein.

[2]Australia v France ICJ Rep (1974) p 253 and New Zealand v France ICJ Rep (1974) p668.

[3] UN General Assembly Resolution No. A/RES/61/34, 18 December 2006, para. 3

[4] 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.