42." Before considering whether the declarations made by the authorities meet the object of the claim by the Applicant that no further atmospheric nuclear tests should be carried out in the South Pacific, it is first necessary to determine the status and scope on the international plane of these declarations.
43." It is well recognized that declarations made by way of unilateral acts, concerning legal or factual situations, may have the effect of creating legal obligations. Declarations of this kind may be, and often are, very specific. When it is the intention of the State making the declaration that it should become bound according to its terms, that intention confers on the declaration the character of a legal undertaking, the State being thenceforth legally required to follow a course of conduct consistent with the declaration. An undertaking of this kind, if given publicly, and with an intent to be bound, even though not made within the context of international negotiations, is binding. In these circumstances, nothing in the nature of a quid pro quo nor any subsequent acceptance of the declaration, nor even any reply or reaction from other States, is required for the declaration to take effect, since such a requirement would be inconsistent with the strictly unilateral nature of the juridical act by which the pronouncement by the State was made.
44." Of course, not all unilateral acts imply obligation; but a State may choose to take up a certain position in relation to a particular matter with the intention of being bound -- the intention is to be ascertained by interpretation of the act. When States make statements by which their freedom of action is to be limited, a restrictive interpretation is called for.
45." With regard to the question of form, it should be observed that this is not a domain in which international law imposes any special or strict requirements. Whether a statement is made orally or in writing makes no essential difference, for such statements made in particular circumstances may create commitments in international law, which does not require that they should be couched in written form. Thus the ques-268tion of form is not decisive. As the Court said in its Judgment on the preliminary objections in the case concerning the Temple of Preah Vihear:
"Where ... as is generally the case in international law, which places the principal emphasis on the intentions of the parties, the law prescribes no particular form, parties are free to choose what form they please provided their intention clearly results from it." (I.C.J. Reports 1961, p. 31.)The Court further stated in the same case: "... the sole relevant question is whether the language employed in any given declaration does reveal a clear intention..." (ibid., p. 32).
46." One of the basic principles governing the creation and performance of legal obligations, whatever their source, is the principle of good faith. Trust and confidence are inherent in international co-operation, in particular in an age when this co-operation in many fields is becoming increasingly essential. Just as the very rule of pacta sunt servanda in the law of treaties is based on good faith, so also is the binding character of an international obligation assumed by unilateral declaration. Thus interested States may take cognizance of unilateral declarations and place confidence in them, and are entitled to require that the obligation thus created be respected.