                     695

                                    SEPARATE OPINION OF JUDGE SIMMA

                        The Court missed an opportunity to clarify a controversial point of law by
                     avoiding to deal with the question whether the exceptio non adimpleti contractus,
                     put forward by the Respondent as a “defence” against the accusation of treaty
                     breach separate, and to be distinguished, from reliance on Article 60 of the
                     1969 Vienna Convention or on a justification of Greece’s objection to FYROM’s
                     admission to NATO by qualifying it as a countermeasure, still has a right of place
                     in international law — the answer which the Court should have given, is an
                     unqualified “no”: Article 60 of the Vienna Convention is to be understood as
                     exhausting the right, flowing from a primary rule of the law of treaties, to suspend
                     performance of a treaty obligation as a reaction to a prior breach by another
                     part — a countermeasure applied in the same context might to an external observer
                     be hard to distinguish from the operation of Article 60, but would be based on a
                     secondary rule of State responsibility and thus be subject to a different legal
                     régime.

                        1. I am in agreement with the findings of the Court with regard to both
                     its jurisdiction and the merits of the case. The only concern I have relates
                     to the way in which the Judgment treats one specific argument advanced
                     by the Respondent, namely the issue of the so‑called exceptio non adim‑
                     pleti contractus.
                        2. To explain my concern and put the matter into context: Greece’s
                     main defence against the Applicant’s accusation of breach of the Interim
                     Accord through the Respondent’s behaviour in the question of the
                     FYROM’s NATO membership was, obviously, to deny such breach alto‑
                     gether and contend that it complied with its obligations under the Accord.
                     But then Greece put forward the alternative argument that even if the
                     Court were to find that the Respondent had violated the Interim Accord,
                     the wrongfulness of Greece’s objection to the admission of the FYROM
                     to NATO would be precluded by — no less than — three justifications
                     (“subsidiary defences”), presented with different degrees of conviction
                     and thus convincingness, as it were, but all based on the allegation of
                     prior breaches of the Interim Accord committed by the Republic of
                     Macedonia: in the first instance by the doctrine of the exceptio non adim‑
                     pleti contractus, secondly, because Greece’s objection could be explained
                     as a response to material breaches of the Accord by the FYROM on the
                     basis of the law of treaties, and thirdly, because Greece’s behaviour could
                     also be regarded as a countermeasure against the FYROM’s preceding
                     breaches recognized as justified by the law of State responsibility.

                     55

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                     696 	       application of interim accord (sep. op. simma)

                        3. The Judgment ultimately rejects all of these defences, and rightly so.
                     It does so for two reasons: to begin with, the Court was only able to find
                     one single, isolated instance in which the Applicant violated the Interim
                     Accord — a breach discontinued after the Respondent had raised its
                     concern (Judgment, paras. 148‑151, 160), and not accepted by the Court
                     as having been material (ibid., para. 163). Furthermore, the Judgment
                     emphasizes that in no case had Greece succeeded in convincing the Court
                     that its objection to Macedonia’s admission to NATO had any factual
                     connection with — i.e., was a response to — the Applicant’s alleged prior
                     treaty breaches, thus possibly giving rise to the various justifications
                     pleaded (ibid., paras. 161, 163-164). I fully support this finding. I am
                     convinced that before and at the time of NATO’s Bucharest meeting, that
                     is, at the time of Greece’s objection to FYROM membership of the
                     Alliance in violation of the Interim Accord, nobody responsible for this
                     course of action in Athens thought of this objection as constituting any of
                     the reactions foreseen in international law to counter a preceding treaty
                     breach by the Applicant, as which it was construed after the fact by Gree‑
                     ce’s counsel in the present litigation, neither in terms of the exceptio nor
                     as a reaction to breach allowed by the law of treaties nor as a counter‑
                     measure in the technical sense. I have difficulties to view Greece’s 2008
                     action as anything but a politically motivated attempt at coercing the
                     FYROM to back down on the name issue. After having been brought
                     before the Court, what the Respondent then tried ex post facto was to
                     hide, somewhat desperately and with a pinch of embarrassment, this
                     show of political force amounting to a treaty breach behind the three
                     juridical fig leaves, presented as “subsidiary defences” by very able coun‑
                     sel (but ad impossibilia nemo tenetur). In the Judgment, these arguments
                     got the treatment they deserved.

                        4. Let me now turn to the specific point on which I take issue with the
                     Court’s approach: the way in which the Judgment goes about the evalua‑
                     tion of the exceptio non adimpleti contractus, put forward, as I have just
                     described, by Greece as a justification separate, and different, from the
                     other two “defences” of response to breach positioned in the law of trea‑
                     ties and that of State responsibility. Greece presented the exceptio as a
                     “general principle of international law” permitting the Respondent to
                     withhold performance of those of its own obligations which are recipro‑
                     cal to, i.e., linked in a synallagmatic relationship with, the fundamental
                     provisions of the Interim Accord allegedly not complied with by the
                     Applicant (thus the description of the Greek position in the Judgment’s
                     paragraph 115). Further (and conveniently), the Respondent contended
                     that “the conditions triggering the exception of non‑performance are
                     different from and less rigid than the conditions for suspending a treaty

                     56

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                     697 	       application of interim accord (sep. op. simma)

                     or precluding wrongfulness by way of countermeasures” (Counter‑
                     Memorial of Greece, para. 8.7); thus, the exception “does not have to be
                     notified or proven beforehand . . . There are simply no procedural require
                     ments to the exercise of the staying of the performance through the
                     mechanism of the exceptio.” (Ibid., para. 8.26.)

                        5. The Applicant, on the contrary, doubted the character of the excep‑
                     tio as a general principle of international law and disputed the Greek
                     contention that its own obligations under the Interim Accord are to be
                     regarded as synallagmatic with the Respondent’s obligation not to object
                     stipulated in Article 11, paragraph 1, of the Accord. In the FYROM’s
                     view, Article 60 of the 1969 Vienna Convention on the Law of Treaties
                     provides a complete set of rules and procedures governing responses to
                     material breaches under that law. Furthermore, the Applicant did not
                     accept that the exceptio could justify non‑performance under the law of
                     State responsibility (thus the summary of the FYROM’s view in para‑
                     graph 117 of the Judgment).

                        6. In the face of such conflicting statements about points of law —
                     arguments playing a non‑negligible role in the framing of the Res‑
                     pondent’s case, whether bordering the specious or not —, one would have
                     expected the Court to go to the heart of the matter and engage in a
                     state‑of‑the‑art exercise of clarifying the legal status and interrelationship
                     of the three “defences” invoked by Greece. However, the Court refrained
                     from doing so. Such abstinence will once again disappoint those obser‑
                     vers who might have expected some illuminating words on rather contro‑
                     versial questions of law; a decision a little less “transactional” in a matter
                     in which the Court could have afforded to speak out. As concerns the
                     exceptio non adimpleti contractus in particular, it appears that the Court
                     openly shies away from taking a stand. Let us see how it deals with the
                     exceptio as invoked by Greece: as I have already mentioned, the Court
                     recalls that the Respondent failed to establish breaches of the Interim
                     Accord save in one immaterial instance and to show a connection between
                     that one breach and the Greek objection to the Applicant’s admission to
                     NATO. And then the Judgment continues as follows:

                            “The Respondent has thus failed to establish that the conditions
                          which it has itself asserted would be necessary for the application of the
                          exceptio have been satisfied in this case. It is, therefore, unnecessary for
                          the Court to determine whether that doctrine forms part of contempo‑
                          rary international law.” (Judgment, para. 161; emphasis added.)
                     That much about jura novit curia. Why such Berührungsangst?

                     57

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                     698 	         application of interim accord (sep. op. simma)

                        7. As far as I am concerned, I may have become immunized against
                     the Court’s apparent haptophobia in my academic childhood, having
                     authored my first scholarly article in English on the question of treaty
                     breach and responses thereto more than 40 years ago 1. So I may be
                     allowed, in all due modesty, to set the record straight and try to compen‑
                     sate the Court’s abstinence as to the exceptio’s whereabouts and “right to
                     life” with the following brief observations 2.

                        8. In its Counter‑Memorial the Respondent defines the exceptio in
                     accordance with the respective entry in the Dictionnaire de droit interna‑
                     tional public:
                             “Literally: [the] ‘exception of a non‑performed contract’. An excep‑
                          tion that the injured Parties can invoke because of the non‑perfor‑
                          mance of a conventional agreement by another contractual Party and
                          which allows in turn not to apply in turn the conventional agreement
                          in part or as a whole.” (Counter‑Memorial of Greece, para. 8.8.)
                        9. Greece distinguishes the exceptio so defined from Article 60 of the
                     Vienna Convention. In its view, while Article 60 presupposes the occur‑
                     rence of material breaches, the exceptio entitles a State to suspend perfor‑
                     mance of its own obligations vis‑à‑vis another State in breach of
                     obligations that do not amount to material breaches (ibid., para. 8.28). I
                     have already drawn attention to Greece’s further statement according to
                     which the exceptio can be resorted to without any procedural precondi‑
                     tions. Lastly, the Respondent argues that “the condition triggering the
                     defence based on the exceptio non adimpleti contractus is that the Appli‑
                     cant State has breached its obligations resulting from the Treaty if said
                     provisions are the quid pro quo of the allegedly breached obligations
                     of the Respondent” (ibid., para. 8.31; see also CR 2011/10, pp. 30‑32,
                     paras. 18‑27).

                         1 B. Simma, “Reflections on Article 60 of the Vienna Convention on the Law of Trea‑

                     ties and Its Background in General International Law”, in 20 Österreichische Zeitschrift
                     für öffentliches Recht, pp. 5‑83 (1970). Since, as the French say, on revient toujours à
                     ses premiers amours, I have returned to my academic first love in a number of further
                     contributions; cf., B. Simma, “Zum Rücktrittsrecht wegen Vertragsverletzung nach der
                     Wiener Konvention von 1969”, in H. Kipp (ed.), Um Recht und Freiheit. Festschrift für
                     F. A. Freiherr von der Heydte, pp. 615‑630 (1977); “Termination and Suspension of Trea‑
                     ties: Two Recent Austrian Cases”, in 21 German Yearbook of International Law, pp. 74‑96
                     (1978); Commentary on Article 60 (together with Christian Tams), in O. Corten and
                     P. Klein (eds.), The Vienna Convention on the Law of Treaties: A Commentary, Vol. II,
                     pp. 1351‑1378 (2011); “Reciprocity”, in R. Wolfrum (ed.), The Max Planck Encyclopedia
                     of Public International Law (online edition 2011).
                         2 They are essentially based on my earlier publications cited in the preceding note, to

                     which I must refer the reader for a more profound treatment of the matter, as well as on
                     some “work in progress” on responses to breach of treaties.

                     58

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                     699 	             application of interim accord (sep. op. simma)

                         10. Even before any assessment of the correctness of Greece’s views,
                     what becomes apparent already now is that the concept of the exceptio
                     flows from the principle of reciprocity. The importance of this notion for
                     the “health” of international law can hardly be overestimated. Recipro‑
                     city constitutes a basic phenomenon of social interaction and conse‑
                     quently a decisive factor also behind the growth and application of law.
                     In fully developed domestic legal systems the idea of reciprocity has to a
                     large extent been absorbed and supplanted by specific norms and institu‑
                     tions; immediate, instinctive, raw, reciprocity has been “domesticated”, as
                     it were. The lower the degree of institutionalization of a legal order,
                     however, the more mechanisms of direct reciprocity will still prevail as
                     such. Hence, its continuing relevance for international law despite the
                     latter’s undeniable movement from bilateralism towards community

                     interest: as long as the international legal order lacks regular and

                     comprehensive mechanisms of centralized enforcement and thus has to
                      live with auto‑determination and self‑help, reciprocity will remain a major
                      leitmotiv — in some instances a constructive force maintaining stability in
                      the law, in some others a threat to that very stability. Reciprocity at the
                      basis of international law thus bears a Janus head: one and the same idea
                      can serve both as a propelling force in the making and keeping of the law
                      and as a trigger in the breakdown of legal order. Focusing on the positive
                      impact of our phenomenon, it will be reciprocal interest in the observance
                      of rules — “each . . . State within the community of nations accepting
                      some subtraction from its full sovereignty in return for similar conces‑
                      sions on the side of the others” 3 — that supplies one, if not the main
                      reason for international law somehow managing to accomplish its tasks,
                      despite the absence of most features considered indispensable by domestic
                      lawyers. The possibility of a State reciprocating in kind a breach of an
                      international obligation will provide a powerful argument for its obser‑
                      vance. The idea of reciprocity therefore lies at the root of various methods
                      of self‑help by which States may secure their rights. The historical dev
                      elopment of these methods provides convincing examples of how “raw”
                      reciprocity has been channelled and civilized by subjecting it to legal
                      limits. In this way, reciprocity has been crystallized into international
                      law’s sanctioning mechanisms, among them reprisals (nowadays politi‑
                      cally correctly called “countermeasures”) and non‑performance of treaties
                      due to breach.

                        11. It is to that second category that the exceptio belongs. To use the
                     terms of the law in force on the matter (Article 60 of the 1969 Vienna
                     Convention on the Law of Treaties, on which infra), if an international
                          3   The Cristina (1938), A.C. 485.

                     59

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                     700 	         application of interim accord (sep. op. simma)

                     treaty has been breached, the other party, or parties, to the treaty may
                     invoke the breach as a ground for terminating it or suspending its opera‑
                     tion; such reaction is permissible as a consequence of — and thus depen‑
                     ding on — the synallagmatic character of international agreements.
                     Expressed a bit more emphatically: “The rule pacta sunt servanda is linked
                     to the rule do ut des” 4; “good sense and equity rebel at the idea of a State
                     being held to the performance of its obligations under a treaty which the
                     other contracting party is refusing to respect” 5.

                        12. The functional synallagma thus confirmed to be applicable also in
                     international law has its historical roots in the law of contracts of most
                     legal systems. Its genealogy can be traced back to the ancient Roman law
                     foundations of the civil law tradition (the Roman bonae fidei judicia) 6, as
                     well as to early English contract law concepts of reciprocity in dependent
                     obligations or mutual promises, the doctrine of consideration, and breach
                     of condition 7. According to what is probably the majority view in inter‑
                     national legal doctrine, the widespread acceptance of the principle in the
                     main legal traditions of the civil and common law systems allows to reco‑
                     gnize it as a general principle of law under Article 38, paragraph 1 (c), of
                     the Court’s Statute.

                        13. The question is, of course, the transferability of such a concept
                     developed in foro domestico to the international legal plane, respectively
                     the amendments that it will have to undergo in order for such a general
                     principle to be able to play a constructive role also at the international
                     level. The problem that we face in this regard is that in fully developed
                     national legal systems the functional synallagma will operate under the
                     control of the courts, that is, at least, such control will always be available
                     if a party affected by its application does not accept the presence of the
                     conditions required to have recourse to our principle. What we encounter
                     at the level of international law, however, will all too often be instances of
                     non‑performance of treaty obligations accompanied by invocation of our
                     principle, but without availability of recourse to impartial adjudication of
                     the legality of these measures 8. Absent the leash of judicial control, our
                     principle will thus become prone to abuse; the issue of legality will often

                        4 M. Bartos in the course of the discussion of what would become Article 60, at the

                     692nd meeting of the International Law Commission, Yearbook of the International Law
                     Commission (YBILC), 1963, Vol. I, p. 124, para. 30.
                        5 H. Waldock, Second Report on the Law of Treaties, commentary to Article 20,

                     para. 1, YBILC, 1963, Vol. II, p. 73.
                        6 R. Zimmermann, The Law of Obligations : Roman Foundations of the Civilian Tradi‑

                     tion, 1990, pp. 801‑802, note 133.
                        7 Ibid., pp. 803‑804.
                        8 For extensive references to State practice, see my 1970 article, op. cit. supra note 1.

                     60

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                     701 	          application of interim accord (sep. op. simma)

                     remain contested; a State resorting to unilateral abrogation might have
                     been

                           “determined for quite other reasons [than an alleged breach] to put an
                           end to the treaty and, having alleged the violation primarily to provide
                           a respectable pretext for its action, has not been prepared to enter into
                           a serious discussion of the legal principles governing the denunciation
                           of treaties on the basis of violations by the other party” 9.
                     The frequency of precisely these circumstances in the relevant State prac‑
                     tice renders state‑of‑the art recognition of the principle’s consecration as
                     customary international law very difficult — a point not always heeded in
                     doctrine.
                        14. The traditional, “standard”, treatment of the functional synal‑
                     lagma in the international legal literature has thus consisted in its recogni‑
                     tion in principle, supported by its apparent matter‑of‑courseness, often
                     with a hint to the existence of a respective general principle, but then fre‑
                     quently accompanied by a warning of the danger of auto‑determination
                     of its pre‑conditions 10. The complications brought about by the emergence
                     of multilateral treaties did not unduly bother the bulk of the literature.

                        15. The recognition of our principle dates back to the classic writers of
                     our discipline. According to Hugo Grotius, for instance, “[i]f one of the
                     parties violates a treaty, such a violation releases the other from its engage‑
                     ments. For every clause has the binding force of a condition.” 11 And in the
                     same sense Emeric de Vattel: “[T]he State which is offended or injured by
                     the failure of the other to carry out the treaty can choose either to force the
                     offender to fulfil its promises or can declare the treaty dissolved because of
                     the violation of its provisions.” 12 Similar statements abound in the litera‑
                     ture up to the time of the Vienna Convention, to which I will turn shortly.
                        16. Among the confirmations of the consequences of synallagmatic
                     treaty provisions in the case of breach in the (pre‑Vienna Convention)
                     jurisprudence of international courts and tribunals, the voices of Judges
                     Anzilotti and Hudson in their opinions in the case of Diversion of Water
                     from the Meuse, decided by the Permanent Court in 1937, are probably
                     most representative. In that case Belgium had contended that by construc‑

                         9 H. Waldock, Second Report on the Law of Treaties, commentary to Article 20, op.

                     cit. supra note 5.
                         10 Extensive references in my 1970 article, op. cit. supra note 1.
                         11 De Iure Belli ac Pacis Libri Tres, Vol. II, Chap. 15, para. 15 (1625; English transla‑

                     tion from B. P. Sinha, Unilateral Denunciation of Treaty because of Prior Violations of
                     Obligations by other Party Nine (1966)).
                         12 Le droit des gens, ou principes de la loi naturelle, appliqués à la conduite et aux affaires

                     des nations et des souverains, Vol. II, Chap. 13, para. 200 (1758; English translation by
                     Fenwick, Carnegie Edition, 1916). For extensive references to the views of early and
                     contemporary writers on our principle, see my 1970 article, op. cit. supra note 1.

                     61

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                     702 	         application of interim accord (sep. op. simma)

                     ting certain works contrary to a nineteenth‑century treaty, the Nether‑
                     lands had forfeited the right to invoke the treaty, and requested the Court
                     to declare that it was entitled to reserve the rights accruing to it from the
                     breaches of the treaty. The Court found that the Netherlands had not
                     breached the treaty and therefore did not pronounce upon Belgium’s
                     contention. Judge Anzilotti took a different view, however, and empha‑
                     sized in his dissenting opinion that he was
                          “convinced that the principle underlying this submission (inadim‑
                          plenti non est adimplendum) is so just, so equitable, so universally
                          recognized, that it must be applied in international relations also. In
                          any case, it is one of these ‘general principles of law recognized by
                          civilized nations’ which the Court applies in virtue of Article 38 of its
                          Statute.” 13
                     In the same vein, Judge Hudson, in his individual opinion in the case,
                     expressed the view
                          “that where two parties have assumed an identical or a reciprocal
                          obligation, one party which is engaged in a continuing non‑perfor‑
                          mance of that obligation should not be permitted to take advantage
                          of a similar non‑performance of that obligation by the other party”. 14
                        17. Like any decent principle, ours, too, got a Latin name, respectively
                     a Latin circumscription — in fact not just one, but several: frangenti fidem
                     non est fides servanda, inadimplenti non est adimplendum, exceptio non(rite)
                     adimpleti contractus 15. Returning to plain English, what is relevant here is
                     that in the overwhelming part of the literature, no distinction was ever, or
                     is currently, made between the maxim inadimplenti non est adimplendum
                     and its expression in the form of an exceptio; both Latin terms pronounce
                     the same principle — inadimplenti in its entirety, the exceptio viewed from
                     the position of a State which, upon another contracting party’s demand
                     for performance of a treaty obligation, responds in the good old Roman
                     law way by connecting its own non‑performance with a breach on the
                     part of the other. This is important in the light of my following point: the
                     “reach” of the codification of our principle in Article 60 of the Vienna
                     Convention.

                        18. In the work of the International Law Commission on the law of
                     treaties, the provision dealing with breach, Article 60, is essentially based
                     on a proposal made by Special Rapporteur H. Waldock in 1963, that is,

                        13 Diversion of Water from the Meuse, Judgment, 1937, P.C.I.J., Series A/B, No. 70,

                     p. 50 (dissenting opinion Judge Anzilotti).
                        14 Ibid., p. 77 (individual opinion Judge Hudson).
                        15 It remained for the editors of the Yearbook of the International Law Commission to

                     combine the two terms by speaking of a maxim exceptio inadimplenti non est adimplendum,
                     and ascribing this strange creation to me: YBILC, 1999, Vol. I, p. 165, para. 41.

                     62

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                     703 	              application of interim accord (sep. op. simma)

                     at a relatively late stage in the legislative history of the Vienna Conven‑
                     tion 16. It developed into a complex Article which, according to the
                     general view, copes quite successfully with the challenge of retaining

                     legal certainty in the face of the many complications in the operation of
                     our principle, in particular of its application to different types of multilateral
                     treaties 17.
                        19. What is decisive in the present context, however, is that Article 60
                     of the Vienna Convention is meant to regulate the legal consequences of
                     treaty breach in an exhaustive way. The exhaustive, conclusive nature of
                     our provision is confirmed by the Convention’s Article 42, paragraph 2,
                     which reads as follows:
                                 “2. The termination of a treaty, its denunciation or the withdrawal
                               of a party, may take place only as a result of the application of the
                               provisions of the treaty or of the present Convention. The same rule
                               applies to suspension of the operation of a treaty.”
                        20. Thus, extra conventionem nulla salus ; on this point, the Applicant got
                     it quite right (cf. paragraph 5 above). But, as a matter of course, Article 42
                          16   For details see my 1970 article, op. cit. supra note 1.
                          17   Article 60 reads as follows:
                                  “Termination or suspension of the operation of a treaty as a consequence of its
                               breach
                               1. A material breach of a bilateral treaty by one of the parties entitles the other to
                                  invoke the breach as a ground for terminating the treaty or suspending its opera‑
                                  tion in whole or in part.
                               2. A material breach of a multilateral treaty by one of the parties entitles:
                                  (a) the other parties by unanimous agreement to suspend the operation of the
                                       treaty in whole or in part or to terminate it either:
                                        (i) in the relations between themselves and the defaulting State; or
                                       (ii) as between all the parties;
                                  (b) a party specially affected by the breach to invoke it as a ground for suspending
                                       the operation of the treaty in whole or in part in the relations between itself
                                       and the defaulting State;
                                  (c) any party other than the defaulting State to invoke the breach as a ground
                                       for suspending the operation of the treaty in whole or in part with respect to
                                       itself if the treaty is of such a character that a material breach of its provisions
                                       by one party radically changes the position of every party with respect to the
                                       further performance of its obligations under the treaty.
                               3. A material breach of a treaty, for the purposes of this article, consists in:
                                  (a) a repudiation of the treaty not sanctioned by the present Convention; or
                                  (b) the violation of a provision essential to the accomplishment of the object or
                                       purpose of the treaty.
                               4. The foregoing paragraphs are without prejudice to any provision in the treaty
                                  applicable in the event of a breach.
                               5.	Paragraphs 1 to 3 do not apply to provisions relating to the protection of the
                                  human person contained in treaties of a humanitarian character, in particular to
                                  provisions prohibiting any form of reprisals against persons protected by such
                                  treaties.”

                     63

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                     704 	             application of interim accord (sep. op. simma)

                      can only reach as far as the Vienna Convention as a whole is intended to
                      reach. This leads us to the Convention’s Article 73, according to which its
                      provisions shall not prejudge any question that may arise in regard to a
                      treaty from, inter alia, the international responsibility of a State. In the
                      language of the ILC, by now generally accepted and adopted in the litera‑
                     ture, the Vienna Convention is designed to provide an exhaustive restate‑
                     ment of the “primary rules” on treaty breach but does not touch upon
                     matters of State responsibility, regulated by “secondary rules” as codified
                     and progressively developed in the ILC’s 2001 Articles. In other words,
                     Article 60 has nothing to do with State responsibility, and State responsi‑
                     bility has nothing to do with the maxim inadimplenti non est adimplendum
                     or the exceptio non adimpleti contractus. The functional synallagma
                     attached to treaties embodying reciprocal obligations finds its (not neces‑
                     sarily Latin) expression entirely in the primary rules of the law of treaties.
                     On the other hand, it is in the law on State responsibility where counter‑
                     measures have found their place, and it is justified, indeed necessary,
                     therefore to deal with them separately — as the Parties to our case have
                      done and as our Judgment does —, even though countermeasures resorted
                      to as a consequence of the breach of a treaty may also lead to suspension of
                      provisions of that same treaty, that is, they may “look alike” for practical
                      purposes while being subjected to a different legal régime — a matter to
                      which I have devoted particular attention in my scholarly contributions 18.

                        21. Returning to the primary rules on the consequences of a breach of
                     treaty embodied in Article 60, let me emphasize once again that this pro‑
                     vision constitutes an exhaustive treatment of the matter. Thus, there is no
                     place left besides it, so to speak, for the exception — Article 60 and the
                     régime provided by the Vienna Convention to complete its operation
                     embodies it.
                        22. I do not want to conceal that in my first publication on the legal
                     régime of treaty breach, I took the view that it would have been advisable
                     for the ILC to leave a — modest — place for the exceptio on the side of
                     Article 60, in the sense that an extra‑conventional exceptio would remain
                     applicable (only) to non‑material or immaterial breaches, with Article 60
                     comprehensively covering the suspension of performance of treaty obliga‑
                     tions as a consequence of “material” breaches as defined in that Article. I
                     thus pleaded for some limited room in general international law left for
                     qualitatively proportional responses by a State in the sense that they may
                     be applied in the form of suspension of the reacting State’s own perfor‑
                     mance if, when and as long as that obligation’s counterpart duty is vio‑
                     lated. This kind of suspension, while constituting a protective measure or
                     remedy with its sedes materiae also in the law of treaties, i.e., in the realm
                          18   Cf. the writings referred to supra in note 1.

                     64

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                     705 	          application of interim accord (sep. op. simma)

                      of primary rules, would not be covered by Article 60 because Article 60
                      de minimis non curat 19. As I mentioned in my description of the argu‑
                     ments of the Parties to our case (cf. supra paragraph 9), Greece put
                      forward this view, but in effect did not profit from it because it regarded
                      the treaty breaches allegedly committed by the FYROM as “material”.
                      As I regard the matter now, I am not convinced that the solution I consi‑
                     dered desirable 40 years ago would be constructive and I do not maintain
                     it. I doubt that it would make sense to let reactions to lesser, immaterial
                     breaches off the leash set up by Article 60, particularly its procedural
                     conditions. Rather, I now join the ranks of those who regard Article 60
                     as truly exhaustive, that is, totally eclipsing the earlier non‑written law on
                     the functional synallagma operating behind treaties. But of course a look
                     across the fence into the realm of State responsibility would still show
                     that the impression of a general de minimis non curat lex possibly created
                     by the Vienna Convention’s lack of consideration of breaches not fulfil‑
                     ling the conditions laid down in Article 60 is misleading because if a
                     breach not “material” enough to trigger the responses codified in that
                     Article were nevertheless to constitute an internationally wrongful act
                     under the law of State responsibility, it would still entitle another affected
                     contracting party, as an injured State, to resort to countermeasures,
                     within the limits of proportionality.

                        23. Article 60 of the Vienna Convention has received the imprimatur
                     by our Court at two earlier occasions, in both instances in ways which
                     confirm that the provision is to be understood as an exhaustive treatment
                     of the consequences of treaty breach under the primary rules of the law of
                     treaties.

                         19 Cf. my 1970 article, op. cit. supra note 1, pp. 59-60. I was not alone with this concern;

                     it was shared 13 years later by the ILC’s Special Rapporteur, W. Riphagen; cf. his fourth
                     report on the content, forms and degrees of international responsibility, YBILC, 1983,
                     Vol. II (Part One), p. 18, para. 98:

                              “Since Article 60 of the Vienna Convention applies only to material breaches, it
                           would be necessary to cover other cases of reciprocity of the performance of treaty
                           obligations. Indeed, if it appears from the treaty or is otherwise established that
                           the performance of an obligation by a State party is the counterpart (quid pro quo)
                           of the performance of the same or another obligation by another State party, the
                           non‑performance by the first mentioned State need not be a material breach in order
                           to justify non‑performance by the other State.”
                        On Professor Riphagen’s subsequent proposal of “reciprocal countermeasures”, see
                     infra note 28.

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                     706 	         application of interim accord (sep. op. simma)

                        24. The first instance was the 1971 Advisory Opinion on Namibia in
                     which the Court, among many other issues, dealt with the declaration by
                     the United Nations General Assembly in its resolution 2145 (XXI) of 1966
                     to the effect that South Africa’s mandate over South West Africa/Namibia
                     was to be regarded as terminated due to material breach by the former
                     mandatory 20. The Court set out by referring rather broadly to the “funda‑
                     mental principl[e] . . . that a party which disowns or does not fulfil its own
                     obligations cannot be recognized as retaining the rights which it claims to
                     derive from the relationship” 21, as well as to its own earlier jurisprudence
                     according to which the mandate constituted an international treaty 22. It
                     then stated that Article 60 of the Vienna Convention (at the time of the
                     rendering of the Opinion still nine years away from its entry into force)
                     “may in many respects be considered as a codification of existing custom‑
                     ary law on the subject” 23. Subsequently, the Court applied the law thus
                     presented to the facts of the case and found that the action of the General
                     Assembly had been justified and had reached the desired effect.
                        25. The second occasion on which the Court applied Article 60 was in
                     its 1997 Judgment in the case of the Gabčikovo‑Nagymaros Project
                     between Hungary and Slovakia, in which one of Hungary’s arguments
                     was to the effect that it was entitled to terminate the 1977 Treaty on the
                     hydro‑electric project on the ground that Czechoslovakia had committed
                     a number of breaches of that treaty 24. The Court took the view that only
                     material breaches gave an affected State a right to terminate an agree‑
                     ment while
                          “[t]he violation of other treaty rules or of rules of general inter
                          national law may justify the taking of certain measures, including
                          countermeasures, by the injured State, but it does not constitute a
                          ground for termination under the law of treaties” 25.
                     Following this statement on the relationship between Article 60 and the
                     law of State responsibility, the Court investigated the breaches alleged
                     by the claimant, in particular Czechoslovakia’s Ersatz construction of
                     “Variant C”, and arrived at the conclusion that the conditions for the
                     invocation of Article 60‑type termination were not fulfilled 26.

                       26. In the light of the foregoing, the pre‑Vienna Convention exceptio is
                     to be declared dead. But I do not want to conclude my opinion without

                        20 Legal Consequences for States of the Continued Presence of South Africa in Namibia

                     (South West Africa) notwithstanding Security Council Resolution 276 (1970), Advisory
                     Opinion, I.C.J. Reports 1971, pp. 46‑50, paras. 91‑104.
                        21 Ibid., p. 46, para. 91.
                        22 Ibid., pp. 46‑47, para. 94.
                        23 Ibid.
                        24 Gabčíkovo‑Nagymaros Project (Hungary/Slovakia), Judgment, I.C.J. Reports 1997,

                     pp. 65‑67, paras. 105‑110.
                        25 Ibid., p. 65, para. 106.
                        26 Ibid., pp. 66‑67, paras. 108‑110.

                     66

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                     707 	         application of interim accord (sep. op. simma)

                     mentioning a recent attempt to resuscitate it, in another legal incarnation,
                     as it were. In the context of the ILC’s work on State responsibility and in
                     the course of the second reading of the Commission’s draft articles on the
                     subject, Special Rapporteur James Crawford, when dealing with the
                     so‑called “Circumstances precluding wrongfulness”, proposed a provi‑
                     sion, draft article 30bis, which had no predecessor in the first‑reading
                     text. The proposal read as follows:
                             “Article 30bis. Non‑compliance caused by prior non‑compliance by
                          another State
                             The wrongfulness of an act of a State not in conformity with an
                          international obligation of that State is precluded if the State has been
                          prevented from acting in conformity with the obligation as a direct
                          result of a prior breach of the same or a related international obliga‑
                          tion by another State.” 27
                       27. Professor Crawford expressly wanted draft article 30bis to restate the
                     exceptio, recognition of which he thought to find in the PCIJ’s Factory
                     at Chorzów (Jurisdiction) Judgment as well as in later decisions. In
                     order to provide a further foundation for his proposal, the Special Rap‑
                     porteur referred to the ILC’s prior codification efforts both relating to the
                     law of treaties and on State responsibility; in the context of the latter to
                     proposals made by Special Rapporteur W. Riphagen introducing so‑called
                     “reciprocal countermeasures” 28.

                        Professor Crawford pleaded for recognition of the exceptio as a distinct
                     circumstance precluding wrongfulness because in his view, it was not
                     enough to deal with it under the law relating to the suspension of treaties
                     because that law required a material breach, which was narrowly
                     defined 29. What we thus see is that the Special Rapporteur wanted to fill
                     what he considered to be a gap in the primary rules of the law of treaties

                        27 For a comprehensive analysis of this article by the Special Rapporteur, see his

                     Second report on State responsibility, YBILC, 1999, Vol. II (Part One), paras. 316‑329.
                        28 YBILC, 1999, Vol. II (Part Two), pp. 78‑79. Professor Riphagen’s concept of “recip‑

                     rocal countermeasures” is to be found in his fifth report on the content, forms and degrees
                     of international responsibility (Part Two of the draft articles), YBILC, 1984, Vol. II (Part
                     One), p. 3. In draft Article 8, Riphagen proposed to express this concept as follows:

                             “Subject to . . . [certain other provisions governing countermeasures], the injured
                          State is entitled, by way of reciprocity, to suspend the performance of its obligations
                          towards the State which has committed an internationally wrongful act, if such obliga‑
                          tions correspond to, or are directly connected with, the obligation breached.” (Ibid.)
                        This proposal was not discussed by the Commission until 1992, when it was rejected;
                     see, YBILC, 1992, Vol. II (Part Two), p. 23, para. 151. For a critique, see B. Simma,
                     “Grundfragen der Staatenverantwortlichkeit in der Arbeit der International Law Commis‑
                     sion”, 24 Archiv des Völkerrechts, pp. 393‑395 (1986).
                        29 YBILC, 1999, Vol. II (Part Two), p. 79.

                     67

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                     (Art. 60) by a secondary rule belonging to the realm of State responsi
                     bility.
                        28. Draft article 30bis got a mixed reception in the Commission, to put
                     it mildly 30. As was to be expected, criticism focused on the relationship
                     between the State‑responsibility re‑appearance of the exceptio now pro‑
                     posed and its expression in the Vienna Convention on the Law of Trea‑
                     ties; the point was made that the proposed article brought together several
                     concepts that were only partially interrelated 31. Overall, the debate was
                     quite confused; for instance, while according to one suggestion, the con‑
                     tent of article 30bis really belonged to the concept of force majeure — an
                     idea which not only the Special Rapporteur found rather odd —, another
                     member regarded the provision as “reflecting a special department of
                     impossibility”; again others were reminded of the “clean hands” princi‑
                     ple 32 and so forth. In light of this, the Commission did well in finally
                     scrapping this doctrinal cross‑breed. In its final report upon adoption of
                     the 2001 Articles on State responsibility, it waved goodbye to the pro‑
                     posal made in draft article 30bis by confirming once again that “the
                     exception of non‑performance (exceptio inadimpleti contractus) is best
                     seen as a specific feature of certain mutual or synallagmatic obligations
                     and not a circumstance precluding wrongfulness” 33.

                        29. Let me summarize: in the present case, the Court would have had
                     the opportunity to clarify a number of legal issues arising from the
                     Respondent’s “defences” against the Applicant’s accusation of treaty
                     breach, in particular, by giving an authoritative answer to the question
                     whether Article 60 of the Vienna Convention on the Law of Treaties still
                     leaves some place for the so‑called exceptio non adimpleti contractus. For
                     some reason, the Court avoided touching upon these issues. In my view,
                     the correct answer would have to be negative: on the plane of interna‑
                     tional law’s primary rules, Article 60 regulates the legal consequences of
                     treaty breach in an exhaustive way; thus no version of the exceptio has
                     survived the codification of the law of treaties — may it rest in peace.

                                                                                (Signed) Bruno Simma.

                        30 Cf. YBILC, 1999, Vol. I, pp. 165‑171, and the summary of the discussion ; ibid., 1999,

                     Vol. II (Part Two), p. 79.
                        31 Ibid.
                        32 Cf. ibid.
                        33 Report of the Commission to the General Assembly on the Work of its Fifty‑Third

                     Session, YBILC, 2001, Vol. II (Part Two), p. 72, para. 9.

                     68

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