86 Report of the International Law Commission on the work of its fifty-third session Commentary (1) Article 27 is a without prejudice clause dealing with certain incidents or consequences of invoking circumstances precluding wrongfulness under chapter V. It deals with two issues. First, it makes it clear that circumstances precluding wrongfulness do not as such affect the underlying obligation, so that if the circumstance no longer exists the obligation regains full force and effect. Secondly, it refers to the possibility of compensation in certain cases. Article 27 is framed as a without prejudice clause because, as to the first point, it may be that the effect of the facts which disclose a circumstance precluding wrongfulness may also give rise to the termination of the obligation and, as to the second point, because it is not possible to specify in general terms when compensation is payable. (2) Subparagraph (a) of article 27 addresses the question of what happens when a condition preventing compliance with an obligation no longer exists or gradually ceases to operate. It makes it clear that chapter V has a merely preclusive effect. When and to the extent that a circumstance precluding wrongfulness ceases, or ceases to have its preclusive effect for any reason, the obligation in question (assuming it is still in force) will again have to be complied with, and the State whose earlier non-compliance was excused must act accordingly. The words “and to the extent” are intended to cover situations in which the conditions preventing compliance gradually lessen and allow for partial performance of the obligation. (3) This principle was affirmed by the tribunal in the “Rainbow Warrior” arbitration,419 and even more clearly by ICJ in the Gabčíkovo-Nagymaros Project case. In considering Hungary’s argument that the wrongfulness of its conduct in discontinuing work on the Project was precluded by a state of necessity, the Court remarked that “[a]s soon as the state of necessity ceases to exist, the duty to comply with treaty obligations revives”.420 It may be that the particular circumstances precluding wrongfulness are, at the same time, a sufficient basis for terminating the underlying obligation. Thus, a breach of a treaty justifying countermeasures may be “material” in terms of article 60 of the 1969 Vienna Convention and permit termination of the treaty by the injured State. Conversely, the obligation may be fully reinstated or its operation fully restored in principle, but modalities for resuming performance may need to be settled. These are not matters which article 27 can resolve, other than by providing that the invocation of circumstances precluding wrongfulness is without prejudice to “compliance with the obligation in question, if and to the extent that the circumstance precluding wrongfulness no longer exists”. Here “compliance with the obligation in question” includes cessation of the wrongful conduct. “compensation”, it is not concerned with compensation within the framework of reparation for wrongful conduct, which is the subject of article 34. Rather, it is concerned with the question whether a State relying on a circumstance precluding wrongfulness should nonetheless be expected to make good any material loss suffered by any State directly affected. The reference to “material loss” is narrower than the concept of damage elsewhere in the articles: article 27 concerns only the adjustment of losses that may occur when a party relies on a circumstance covered by chapter V. (5) Subparagraph (b) is a proper condition, in certain cases, for allowing a State to rely on a circumstance precluding wrongfulness. Without the possibility of such recourse, the State whose conduct would otherwise be unlawful might seek to shift the burden of the defence of its own interests or concerns onto an innocent third State. This principle was accepted by Hungary in invoking the plea of necessity in the Gabčíkovo-Nagymaros Project case. As ICJ noted, “Hungary expressly acknowledged that, in any event, such a state of necessity would not exempt it from its duty to compensate its partner”.421 (6) Subparagraph (b) does not attempt to specify in what circumstances compensation should be payable. Generally, the range of possible situations covered by chapter V is such that to lay down a detailed regime for compensation is not appropriate. It will be for the State invoking a circumstance precluding wrongfulness to agree with any affected States on the possibility and extent of compensation payable in a given case. Part Two CONTENT OF THE INTERNATIONAL RESPONSIBILITY OF A STATE (1) Whereas Part One of the articles defines the general conditions necessary for State responsibility to arise, Part Two deals with the legal consequences for the responsible State. It is true that a State may face legal consequences of conduct which is internationally wrongful outside the sphere of State responsibility. For example, a material breach of a treaty may give an injured State the right to terminate or suspend the treaty in whole or in part.422 The focus of Part Two, however, is on the new legal relationship which arises upon the commission by a State of an internationally wrongful act. This constitutes the substance or content of the international responsibility of a State under the articles. (4) Subparagraph (b) of article 27 is a reservation as to questions of possible compensation for damage in cases covered by chapter V. Although the article uses the term (2) Within the sphere of State responsibility, the consequences which arise by virtue of an internationally wrongful act of a State may be specifically provided for in such terms as to exclude other consequences, in whole or 419 “Rainbow Warrior” (see footnote 46 above), pp. 251–252, para. 75. 420 Gabčíkovo-Nagymaros Project (see footnote 27 above), p. 63, para 101; see also page 38, para. 47. 421 Ibid., p. 39, para. 48. A separate issue was that of accounting for accrued costs associated with the Project (ibid., p. 81, paras. 152– 153). 422 1969 Vienna Convention, art. 60.