State responsibility peremptory norms makes it clear that subparagraph (d) does not qualify the preceding subparagraphs, some of which also encompass norms of a peremptory character. In particular, subparagraphs (b) and (c) stand on their own. Subparagraph (d) allows for the recognition of further peremptory norms creating obligations which may not be the subject of countermeasures by an injured State.768 (10) States may agree between themselves on other rules of international law which may not be the subject of countermeasures, whether or not they are regarded as peremptory norms under general international law. This possibility is covered by the lex specialis provision in article 55 rather than by the exclusion of countermeasures under article 50, paragraph 1 (d). In particular, a bilateral or multilateral treaty might renounce the possibility of countermeasures being taken for its breach, or in relation to its subject matter. This is the case, for example, with the European Union treaties, which have their own system of enforcement.769 Under the dispute settlement system of WTO, the prior authorization of the Dispute Settlement Body is required before a member can suspend concessions or other obligations under the WTO agreements in response to a failure of another member to comply with recommendations and rulings of a WTO panel or the Appellate Body.770 Pursuant to article 23 of the WTO Dispute Settlement Understanding (DSU), members seeking “the redress of a violation of obligations or other nullification or impairment of benefits” under the WTO agreements, “shall have recourse to, and abide by” the DSU rules and procedures. This has been construed both as an “exclusive dispute resolution clause” and as a clause “preventing WTO members from unilaterally resolving their disputes in respect of WTO rights and obligations”.771 To the extent that derogation clauses or other treaty provisions (e.g. those prohibiting reservations) are properly interpreted as indicating that the treaty provisions are “intransgressible”,772 they may entail the exclusion of countermeasures. (11) In addition to the substantive limitations on the taking of countermeasures in paragraph 1 of article 50, paragraph 2 provides that countermeasures may not be taken with respect to two categories of obligations, viz. certain obligations under dispute settlement procedures applicable between it and the responsible State, and obligations with 768 See paragraphs (4) to (6) of the commentary to article 40. the exclusion of unilateral countermeasures in European Union law, see, for example, joined cases 90 and 91‑63 (Commission of the European Economic Community v. Grand Duchy of Luxembourg and Kingdom of Belgium), Reports of cases before the Court, p. 625, at p. 631 (1964); case 52/75 (Commission of the European Communities v. Italian Republic), ibid., p. 277, at p. 284 (1976); case 232/78 (Commission of the European Economic Communities v. French Republic), ibid., p. 2729 (1979); and case C-5/94 (The Queen. v. Ministry of Agriculture, Fisheries and Food, ex parte Hedley Lomas (Ireland) Ltd.), Reports of cases before the Court of Justice and the Court of First Instance, p. I–2553 (1996). 770 See Marrakesh Agreement establishing the World Trade Organization, annex 2 (Understanding on Rules and Procedures governing the Settlement of Disputes), arts. 3, para. 7 and 22. 771 See WTO, Report of the Panel, United States–Sections 301–310 of the Trade Act of 1974 (footnote 73 above), paras. 7.35–7.46. 772 To use the synonym adopted by ICJ in its advisory opinion on Legality of the Threat or Use of Nuclear Weapons (see footnote 54 above), p. 257, para. 79. 769 On 133 respect to diplomatic and consular inviolability. The justification in each case concerns not so much the substantive character of the obligation but its function in relation to the resolution of the dispute between the parties which has given rise to the threat or use of countermeasures. (12) The first of these, contained in paragraph 2 (a), applies to “any dispute settlement procedure applicable” between the injured State and the responsible State. This phrase refers only to dispute settlement procedures that are related to the dispute in question and not to other unrelated issues between the States concerned. For this purpose the dispute should be considered as encompassing both the initial dispute over the internationally wrongful act and the question of the legitimacy of the countermeasure(s) taken in response. (13) It is a well-established principle that dispute settlement provisions must be upheld notwithstanding that they are contained in a treaty which is at the heart of the dispute and the continued validity or effect of which is challenged. As ICJ said in Appeal Relating to the Jurisdiction of the ICAO Council: Nor in any case could a merely unilateral suspension per se render jurisdictional clauses inoperative, since one of their purposes might be, precisely, to enable the validity of the suspension to be tested.773 Similar reasoning underlies the principle that dispute settlement provisions between the injured and the responsible State and applicable to their dispute may not be suspended by way of countermeasures. Otherwise, unilateral action would replace an agreed provision capable of resolving the dispute giving rise to the countermeasures. The point was affirmed by the Court in the United States Diplomatic and Consular Staff in Tehran case: In any event, any alleged violation of the Treaty [of Amity] by either party could not have the effect of precluding that party from invoking the provisions of the Treaty concerning pacific settlement of disputes.774 (14) The second exception in paragraph 2 (b) limits the extent to which an injured State may resort, by way of countermeasures, to conduct inconsistent with its obligations in the field of diplomatic or consular relations. An injured State could envisage action at a number of levels. To declare a diplomat persona non grata, to terminate or suspend diplomatic relations, to recall ambassadors in situations provided for in the Vienna Convention on Diplomatic Relations—such acts do not amount to countermeasures in the sense of this chapter. At a second level, measures may be taken affecting diplomatic or consular privileges, not prejudicing the inviolability of diplomatic or consular personnel or of premises, archives and documents. Such measures may be lawful as countermeasures if the requirements of this chapter are met. On the other hand, the scope of prohibited countermeasures under article 50, paragraph 2 (b), is limited to those obligations which are designed to guarantee the physical safety and inviolability (including the jurisdictional immunity) of diplomatic agents, premises, archives and documents in 773 Appeal Relating to the Jurisdiction of the ICAO Council (India v. Pakistan), Judgment, I.C.J. Reports 1972, p. 46, at p. 53. See also S. M. Schwebel, International Arbitration: Three Salient Problems (Cambridge, Grotius, 1987), pp. 13–59. 774 United States Diplomatic and Consular Staff in Tehran (see footnote 59 above), p. 28, para. 53.