State responsibility 63 continuing breaches, but simple acts can cause continuing breaches as well. The position is different, however, where the obligation itself is defined in terms of the cumulative character of the conduct, i.e. where the cumulative conduct constitutes the essence of the wrongful act. Thus, apartheid is different in kind from individual acts of racial discrimination, and genocide is different in kind from individual acts even of ethnically or racially motivated killing. (7) A consequence of the character of a composite act is that the time when the act is accomplished cannot be the time when the first action or omission of the series takes place. It is only subsequently that the first action or omission will appear as having, as it were, inaugurated the series. Only after a series of actions or omissions takes place will the composite act be revealed, not merely as a succession of isolated acts, but as a composite act, i.e. an act defined in aggregate as wrongful. (5) In Ireland v. the United Kingdom, Ireland complained of a practice of unlawful treatment of detainees in Northern Ireland which was said to amount to torture or inhuman or degrading treatment, and the case was held to be admissible on that basis. This had various procedural and remedial consequences. In particular, the exhaustion of local remedies rule did not have to be complied with in relation to each of the incidents cited as part of the practice. But the Court denied that there was any separate wrongful act of a systematic kind involved. It was simply that Ireland was entitled to complain of a practice made up by a series of breaches of article VII of the Convention on the Prevention and Punishment of the Crime of Genocide, and to call for its cessation. As the Court said: (8) Paragraph 1 of article 15 defines the time at which a composite act “occurs” as the time at which the last action or omission occurs which, taken with the other actions or omissions, is sufficient to constitute the wrongful act, without it necessarily having to be the last in the series. Similar considerations apply as for completed and continuing wrongful acts in determining when a breach of international law exists; the matter is dependent upon the precise facts and the content of the primary obligation. The number of actions or omissions which must occur to constitute a breach of the obligation is also determined by the formulation and purpose of the primary rule. The actions or omissions must be part of a series but the article does not require that the whole series of wrongful acts has to be committed in order to fall into the category of a composite wrongful act, provided a sufficient number of acts has occurred to constitute a breach. At the time when the act occurs which is sufficient to constitute the breach it may not be clear that further acts are to follow and that the series is not complete. Further, the fact that the series of actions or omissions was interrupted so that it was never completed will not necessarily prevent those actions or omissions which have occurred being classified as a composite wrongful act if, taken together, they are sufficient to constitute the breach. A practice incompatible with the Convention consists of an accumulation of identical or analogous breaches which are sufficiently numerous and inter-connected to amount not merely to isolated incidents or exceptions but to a pattern or system; a practice does not of itself constitute a violation separate from such breaches* ... The concept of practice is of particular importance for the operation of the rule of exhaustion of domestic remedies. This rule, as embodied in Article 26 of the Convention, applies to State applications ... in the same way as it does to “individual” applications ... On the other hand and in principle, the rule does not apply where the applicant State complains of a practice as such, with the aim of preventing its continuation or recurrence, but does not ask the Commission or the Court to give a decision on each of the cases put forward as proof or illustrations of that practice.259 In the case of crimes against humanity, the composite act is a violation separate from the individual violations of human rights of which it is composed. (6) A further distinction must be drawn between the necessary elements of a wrongful act and what might be required by way of evidence or proof that such an act has occurred. For example, an individual act of racial discrimination by a State is internationally wrongful,260 even though it may be necessary to adduce evidence of a series of acts by State officials (involving the same person or other persons similarly situated) in order to show that any one of those acts was discriminatory rather than actuated by legitimate grounds. In its essence such discrimination is not a composite act, but it may be necessary for the purposes of proving it to produce evidence of a practice amounting to such an act. 259 Ireland v. the United Kingdom (see footnote 236 above), p. 64, para. 159; see also page 63, para. 157. See further the United States counterclaim in Oil Platforms (Islamic Republic of Iran v. United States of America), Counter-Claim, Order of 10 March 1998, I.C.J. Reports 1998, p. 190, which likewise focuses on a general situation rather than specific instances. 260 See, e.g., article 2 of the International Convention on the Elimination of All Forms of Racial Discrimination; and article 26 of the International Covenant on Civil and Political Rights. (9) While composite acts are made up of a series of actions or omissions defined in aggregate as wrongful, this does not exclude the possibility that every single act in the series could be wrongful in accordance with another obligation. For example, the wrongful act of genocide is generally made up of a series of acts which are themselves internationally wrongful. Nor does it affect the temporal element in the commission of the acts: a series of acts or omissions may occur at the same time or sequentially, at different times. (10) Paragraph 2 of article 15 deals with the extension in time of a composite act. Once a sufficient number of actions or omissions has occurred, producing the result of the composite act as such, the breach is dated to the first of the acts in the series. The status of the first action or omission is equivocal until enough of the series has occurred to constitute the wrongful act; but at that point the act should be regarded as having occurred over the whole period from the commission of the first action or omission. If this were not so, the effectiveness of the prohibition would thereby be undermined. (11) The word “remain” in paragraph 2 is inserted to deal with the intertemporal principle set out in article 13. In accordance with that principle, the State must be bound by the international obligation for the period during which the series of acts making up the breach is committed. In