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Published online by Cambridge University Press:  12 October 2015


Comparing the EU law principle of loyalty with international law good faith and the duty of federal good faith in German constitutional law (Bundestreue), this article contributes to the discussion on the nature of the EU legal order and its relationship to international law more generally by finding that EU loyalty is in essence a specific incarnation of the international law principle that treaties are to be interpreted in good faith. At the same time, it challenges the assumption that international law good faith differs fundamentally from federal good faith. To this end, the article points at historical links between both, and posits that good faith is in essence a principle of constructive interpretation, the strictures of which increase with the level of integration of the legal order in which it is applied.

Copyright © British Institute of International and Comparative Law 2015 

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1 Both in the case law of the ECJ and in scholarly writings, that principle has been referred to under various names ranging from ‘good faith’, ‘loyalty’ or ‘loyal cooperation’ to ‘fidelity’. Art 4(3) TEU now refers to the ‘principle of sincere cooperation’. The Court coined the latter term in the judgment in Luxembourg v European Parliament, 230/81, EU:C:1983:32, para 37, in which it also recognized the mutual character of the loyalty obligation. The Treaty of Lisbon has codified the mutual character of loyalty in art 4(3) TEU (‘in full mutual respect’; see also art 13(2) TEU and art 24(3) TEU, which speak of ‘mutual sincere cooperation’ and ‘mutual solidarity’, respectively). Perhaps the origins of that mutual character in Luxembourg v European Parliament inspired the Treaty Drafters also to adopt the latter judgment's term for loyalty.

2 Under the first para of art 19(1) TEU, the institution of the Court of Justice of the EU encompasses the Court of Justice, the General Court and specialized courts (at present, the EU Civil Service Tribunal). For reasons of clarity, this chapter refers to the Court of Justice as the European Court of Justice (‘ECJ’ or ‘the Court’) in the sense of the highest court of this institution.

3 See eg Casteleiro, A Delgado and Larik, J, ‘The Duty to Remain Silent: Limitless Loyalty in EU External Relations?’ (2011) 36 ELR 524Google Scholar; Neframi, E, ‘The Duty of Loyalty: Rethinking its Scope through its Application in the Field of EU External Relations’ (2010) 47 CMLRev 323Google Scholar. In particular, the ‘open-ended nature’ of loyalty remains a cause of concern: eg G Conway, The Limits of Legal Reasoning and the European Court of Justice (CUP 2012) 140–1; Baere, G De, ‘“O, Where is Faith? O, Where is Loyalty?” Some Thoughts on the Duty of Loyal Co-operation and the Union's External Environmental Competences in the Light of the PFOS Case’ (2011) 36 ELR 405Google Scholar.

4 Opinion 2/13, Accession to the ECHR, EU:C:2014:2454, para 157 (emphasis added); see most recently the judgment in Commission v Council, C-28/12, EU:C:2015:282, para 39.

5 The ECSC entered into force on 23 July 1952 and expired on 23 July 2002.

6 Art 86 ECSC; art 192 of the Treaty establishing the European Atomic Energy Community (EAEC); art 5 of the Treaty establishing the European Economic Community (EEC), which after the Maastricht Treaty became art 5 of the Treaty establishing the European Community (EC) and after the Amsterdam Treaty art 10 EC. The Court has explicitly developed art 86 ECSC, art 192 EAEC, and art 5 EEC/art 10 EC in parallel. See eg the judgments in Allain, C-341/94, EU:C:1996:356, para 24; Banks, C-390/98, EU:C:2001:456, para 121; Francovich and Others, C-6/90 and C-9/90, EU:C:1991:428, para 36; Commission v Ireland (‘Mox Plant’), C-459/03, EU:C:2006:345, para 174; and ČEZ, C-115/08, EU:C:2009:660, para 138. Although the text of the second sentence of art 86 ECSC does not correspond to the text of its counterpart in the E(E)C, the ECJ considers it as an expression of the same principle: Banks, para 121.

7 See art 1, para 3 TEU.

8 ‘The States party to the present treaty undertake to adopt, within the scope of their jurisdiction, all general or particular measures to ensure the execution of their obligations under the decisions and recommendations of the organs of the Community and to facilitate the accomplishment of the latter's mission’ (our translation): Première Redaction du Projet de Traité (‘Plan Schuman’), 8 November 1950, 86, consulted at the Archives of the Belgian Ministry of Foreign Affairs (Brussels), Dossier No 12284.

9 Literally translated, the term ‘State parties’ was replaced by ‘Member States’, ‘organs of the Community’ by ‘institutions of the Community’, and the phrase ‘within the scope of their jurisdiction’ was deleted.

10 See further B Simma, The UN Charter: A Commentary (OUP 2002) 92ff. The Heads of State and Government, and heads of delegation gathered at UN Headquarters in New York on 24 September 2012 to reaffirm their commitment to the rule of law also ‘rededicated’ themselves to ‘the fulfilment in good faith of the obligations assumed in accordance with the Charter’: UN Doc A/RES/67/1, para 3. As the International Court of Justice (ICJ) pointed out in Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) notwithstanding Security Council Resolution 276 (1970), Advisory Opinion, ICJ Reports (1971) 16, 46, para 90, member States have undertaken to fulfil in good faith the relevant obligations emanating from the UN Charter ‘in all their international relations’; cf J Crawford, Chance, Order, Change: The Course of International Law. General Course on Public International Law (Hague Academy of International Law 2014) 458–9, who regards that passage as illustrating that the UN Charter is not just universal in the sense that practically all States have ratified it, but that it also makes ‘a more fundamental claim to universality’.

11 Exchange of Greek and Turkish Populations, 1925 PCIJ Reports Series B, No 10, 20. See also Jurisdiction of the Courts of Danzig, 1928 PCIJ Series B, No 15, 26–27. See further E Zoller, La Bonne Foi en Droit International Public (Pédone 1977) 94.

12 Simma (n 10) 92–3 and the sources mentioned there.

13 See eg judgment in Groupement des Industries Sidérurgiques Luxembourgeoises, 7 and 9/54, EU:C:1956:2, at 190.

14 Judgment in Germany v Commission, C-276/99, EU:C:2001:576, para 23 and the case law referred to there.

15 Concluded on 23 May 1969, UN Doc A/Conf.39/27; 1155 UNTS 331; 8 ILM 679 (1969); 63 AJIL 875 (1969).

16 UNYBILC (vol II) (1964) 7.

17 ibid 177.

18 Land and Maritime Boundary between Cameroon and Nigeria (Preliminary Objections, Judgment), ICJ Reports (1998) 296, para 38, also noting that it was mentioned as early as the beginning of the twentieth century in the Arbitral Award of 7 September 1910 in The North Atlantic Fisheries Case, 11 UNRIAA, 188. It was upheld in several judgments of the PCIJ (Factory at Chorzow (Merits), 1928 PCIJ Series A, No 17, 30; Free Zones of Upper Savoy and the District of Gex, 1932 PCIJ Series A, No 24, at 12, and 1932 PCIJ Series A/B, No 46, at 167) and it was applied by the ICJ as early as 1952 in the case concerning Rights of Nationals of the United States of America in Morocco (Judgment), ICJ Reports (1952) 212, then in Fisheries Jurisdiction (Jurisdiction of the Court, Judgment), ICJ Reports (1973) 18, the Nuclear Tests cases, ICJ Reports (1974) 268 and 473, and Border and Transborder Armed Actions (Jurisdiction and Admissibility, Judgment), ICJ Reports (1988) 105.

19 J Temple Lang, ‘Article 10 EC – The Most Important ‘‘General Principle’’ of Community Law’ in U Bernitz et al. (eds), General Principles of EC Law in a Process of Development (Wolters Kluwer 2008) 76. See already P Hay, Federalism and Supranational Organizations: Patterns for New Legal Structures (Urbana 1966) 196. The Court first referred to art 5 EEC as the codification of a more general ‘principle of cooperation’ in the judgments in Rewe-Zentralfinanz, 33/76, EU:C:1976:188, para 5 and Comet, 45/76, EU:C:1976:19, para 12.

20 See also art 34(2) TEU.

21 Judgment in Kempter, C-2/06, EU:C:2008:78, para 42. See also for example the judgment in Petru, C-268/13, EU:C:2014:2271, para 20 and the case law cited there.

22 Judgments in Thieffry, 71/76, EU:C:1977:65, para 16; Unectef, 222/86, EU:C:1987:442, paras 11–13; Vlassopoulou, C-340/89, EU:C:1991:193, paras 14–17; A Verhoeven, The European Union in Search of a Democratic and Constitutional Theory (Kluwer Law International 2002) 308.

23 See the Opinions of Advocates General Tizzano in Budvar, C-216/01, EU:C:2003:302, point 150; and Poiares Maduro in Kadi v Council and Commission, C402/05 P, EU:C:2008:11, point 32; Al Barakaat International Foundation v Council and Commission, C-415/05 P, EU:C:2008:30, point 32; and in Commission v Austria, C-205/06 and Commission v Sweden, C-249/06, EU:C:2008:391, point 33.

24 Council Decision 2010/427/EU of 26 July 2010 establishing the organization and functioning of the European External Action Service, OJ 2010 L201/30.

25 See S Blockmans and C Hillion (eds), EEAS 2.0. A Legal Commentary on Council Decision 2010/427/EU establishing the organisation and functioning of the European External Action Service (CLEER Working Papers 2013) 1, 28ff.

26 Judgments in Compagnie Commerciale de l'Ouest, C-78 to 83/90, EU:C:1992:118, para 19; Commission v Germany, C-195/90, EU:C:1992:219, paras 36–38; Domingo Banchero, C-387/93, EU:C:1995:439, para 17.

27 Judgments in Luxembourg v European Parliament (n 1) para 37; Commission v Greece, C-45/07, EU:C:2009:81, paras 25–26; Ireland v Commission, C-339/00, EU:C:2003:545, paras 71–76. See also the judgment in Aayhan and Others v Parliament, F-65/07, EU:F:2009:43, paras 118–119, in which the Civil Service Tribunal of the EU held that it follows from ‘the duty to cooperate in good faith’ that ‘it is incumbent on the institutions to ensure as far as possible consistency between their own internal policy and their legislative action at [Union] level, in particular as addressed to Member States’.

28 Judgment in Luxembourg v European Parliament (n 1); Order in Zwartveld, C-2/88 IMM, EU:C:1990:315; see also judgment in UK v Commission, C-337/89, EU:C:1992:456, para 12.

29 Art 13(2) TEU, which codifies ECJ case law to the same effect, eg the judgments in Greece v Council, 204/86, EU:C:1988:450, para 16; European Parliament v Council, C-65/93, EU:C:1995:91, para 23; Commission v Council, C-29/99, EU:C:2002:734. As the ECJ held in the judgment in Commission v Council, C-425/13, EU:C:2015:483, para 64, that cooperation pursuant to art 13(2) TEU ‘is of particular importance for EU action at international level, as such action triggers a closely circumscribed process of concerted action and consultation between the EU institutions’; see eg the application for annulment of a Commission decision on the signature of an Addendum to a Memorandum of Understanding with Switzerland in Council v Commission, C-660/13, OJ 2014 C 45/26, the second plea of which argues that the Commission has infringed the principle of sincere cooperation contained in art 13(2) TEU. In the judgment in Parliament v Council, C-48/14, EU:C:2015:91, para 58, the Court further clarified that sincere cooperation pursuant to art 13(2) is exercised ‘within the limits of the powers conferred by the Treaties on each institution’. That implies that the obligation resulting from art 13(2) TEU is ‘not such as to change those powers’. In other words, the obligation to cooperate sincerely cannot detract from the duty to respect the principle of conferral. See also in that sense the Opinion of Advocate General Sharpston in Council v Commission, C-73/14, EU:C:2015:490, points 98–102. See further K Lenaerts and J Gutiérrez-Fons, ‘To Say What the Law of the EU Is: Methods of Interpretation and the European Court of Justice’ (2014) 20 Columbia Journal of European Law 5, arguing that the ECJ must, in the exercise of its jurisdiction, pay due attention to the principle of inter-institutional balance and of the principle of mutual sincere cooperation set out in art 13(2) TEU. Similarly, see Horsley, T, ‘Reflections on the Role of the Court of Justice as the ‘‘Motor’’ of European Integration: Legal Limits to Judicial Lawmaking’ (2013) 50 CMLRev 931Google Scholar.

30 Judgments in Athanasopoulos and Others, C-251/89, EU:C:1991:242, para 57; Van Munster, C-165/91, EU:C:1994:359, para 32; IKA, C-326/00, EU:C:2003:101; and FTS, C-202/97, EU:C:2000:75, paras 51 and 56. See also the Opinions of Advocates General Sharpston in Bressol and Others, C-73/08, EU:C:2009:396, point 154 and Bot in Hungary v Slovakia, C-364/10, EU:C:2012:124, points 58–60.

31 Temple Lang (n 19) 76.

32 Francovich (n 6) para 36.

33 Rewe-Zentralfinanz (n 19) para 5 (‘impossible in practice’). cf the judgment in Surgicare, C-662/13, EU:C:2015:89 (‘impossible in practice or excessively difficult’). The ECJ explicitly confirmed that the principle of effectiveness finds its basis in sincere cooperation enshrined in art 4(3) TEU in the judgment in Commission v United Kingdom, C-640/13, EU:C:2014:2457, para 32.

34 Judgment in Peterbroeck, C-312/93, EU:C:1995:437. See also the Opinion of AG Saggio in Océano Grupo, C-240/98 to C-244/98, EU:C:1999:620, point 38.

35 Judgment in Kühne & Heitz, C-453/00, EU:C:2004:17, paras 24–27.

36 Judgment in Laboratoires Boiron, C-526/04, EU:C:2006:528, paras 55 and 57.

37 Judgment in Commission v Council (‘ERTA’), 22/70, EU:C:1971:32, para 22. ERTA is authority for the existence of implied external competences on the basis of the existence of internal Union rules and for the acquisition of exclusive external competences on the same basis. The former aspect is now codified in art 216(1) TFEU, while the latter aspect is codified in art 3(2) TFEU.

38 ibid para 17.

39 Judgment in Costa v ENEL, 6/64, EU:C:1964:66, 593–594. See below, section III.

40 eg V Constantinesco, ‘L'article 5 CEE, de la bonne foi à la loyauté communautaire’ in V Constantinesco et al. (eds), Du droit international au droit de l'intégration. Liber amicorum P Pescatore (Nomos 1987) 101; A Bleckmann, ‘Die Bindungswirkung der Praxis der Organe und der Mitgliedstaaten der EG bei der Auslegung und Lückenfüllung des Europäischen Gemeinschaftsrechts: Die Rolle des Art. 5 EWG-Vertrag’ and MA Dauses, ‘Quelques réflexions sur la signification et la portée de l'article 5 du traité CEE’, both in R Bieber and G Ress (eds), Die Dynamik des Europäischen Gemeinschaftsrechts: die Auslegung des Europäischen Gemeinschaftsrechts im Lichte nachfolgender Praxis der Mitgliedstaaten und der EG-Organe (Nomos 1987) 191 and 229, respectively; M Lück, Die Gemeinschaftstreue als allgemeines Rechtsprinzip im Recht der Europäischen Gemeinschaft: ein Vergleich zur Bundestreue im Verfassungsrecht der Bundesrepublik Deutschland (Nomos 1992); H Bauer, Die Bundestreue: zugleich ein Beitrag zur Dogmatik des Bundesstaatsrechts und zur Rechtsverhältnislehre (Mohr Siebeck 1992) 206; Verhoeven (n 22) 306; K Lenaerts and P Van Nuffel (N Cambien (ed)), European Union Law (Sweet & Maxwell 2011) 147–8; F Casolari, ‘The Principle of Loyal Co-Operation: A ‘‘Master Key’’ for EU External Representation?’ CLEER Working Papers 2012/5, 11; M Klamert, The Principle of Loyalty in EU Law (OUP 2014) 55–8.

41 Constantinesco (n 40); Dauses (n 40); M Blanquet, L'article 5 du traité CEE. Recherche sur les obligations de fidélité des États Membres de la Communauté (LGDJ 1994) 29–34.

42 eg Blanquet (n 41) 33–4.

43 Opinion 2/13 (n 4), paras 156–158.

44 J Crawford, The Creation of States in International Law (OUP 2006) 495.

45 See (n 37) above.

46 Eg judgment in Commission v Luxembourg, C-266/03, EU:C:2005:341, paras 57–60.

47 See art 2 of the Vienna Convention of 18 April 1961 on Diplomatic Relations, 500 UNTS 212. See also art 2(1) and (2) of the Vienna Convention of 24 April 1963 on Consular Relations, 500 UNTS 95. cf the Opinion of AG Bot in Hungary v Slovakia (n 30), point 57.

48 Opinion of AG Bot in Hungary v Slovakia (n 30), points 58–59.

49 See eg Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy, OJ 2000 L 327/1 (which imposes administrative coordination with regard to the management of international river basins, both between EU Member States and with non-Member States).

50 Gabčíkovo-Nagymaros Project (Judgment), ICJ Reports (1997) 7, paras 136–142, 155 (discussed below).

51 See further, eg on good faith as the basis for the binding nature of unilateral declarations: Nuclear Tests cases (n 18) 268, para 46 and 473, para 49 (for a deconstruction, see M Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (CUP 2005) 345–55); and good faith as the basis for acquiescence and estoppel in general international law: Delimitation of the Maritime Boundary in the Gulf of Maine Area (Judgment), ICJ Reports (1984) 246, 305, para 130.

52 Judgment in Racke v Hauptzollamt Mainz, C-162/96, EU:C:1998:293, para 49.

53 Greco-Turkish Arbitral Tribunal, Megalidis, 8 TAM (1928) 395.

54 cf Spiermann, O, ‘The Other Side of the Story: An Unpopular Essay on the Making of the European Community Legal Order’ (1999) 10 EJIL 785CrossRefGoogle Scholar (with respect to precedence).

55 In the authentic Italian text of the judgment, this passage reads: ‘Se l'efficacia del diritto comunitario variasse da uno stato all'altro in funzione delle leggi interne posteriori, ciò metterebbe in pericolo l'attuazione degli scopi del Trattato contemplata nell'art. 5, secondo comma, e causerebbe una discriminazione vietata dall'art. 7’ (emphasis added). That seems to indicate that ‘intended by’ is preferable to ‘set out in’, which is used in the official English translation. That appears to be confirmed by the French text of the judgment (traditionally the text drafted and deliberated by the judges), which reads: ‘Que la force executive du droit communautaire ne saurait, en effet, varier d'un État à l'autre à la faveur des législations internes ultérieures, sans mettre en peril la réalisation des buts du Traité visée à l'Article 5(2), ni provoquer une discrimination interdite par l'Article 7’ (emphasis added). The female ‘contemplata’ in Italian and ‘visée’ in French, which correspond, respectively, to ‘l'attuazione’ and ‘la réalisation’, clarify that the Court was referring to, respectively, ‘l'attuazione degli scopi del Trattato’ and ‘la realisation des buts du Traité’ as the expression used in art 5, not to any objectives in art 5 itself.

56 Costa (n 39) 593–594. cf Lenaerts and Gutiérrez-Fons (n 29) 32, fn 197, citing this passage as an example of ‘consequentialist interpretation’. Having established the primacy of EU law on that basis, the Court as a rule stopped referring to loyalty as a source for the binding character of provisions of (primary or secondary) EU law and now simply refers to the provisions themselves. Examples of judgments that rely on art 86 ECSC to establish the binding character of EU law measures include the judgments in Groupement des Industries Sidérurgiques Luxembourgeoises (n 13) 190; Germany v High Authority, Case 3/59, EU:C:1960:9, 60; Humblet, 6/60, EU:C:1960:48, 569; Gerlach, 239/84, EU:C:1960:48, para 12.

57 eg Weiler, J, ‘The Transformation of Europe’ (1991) 100 YaleLJ 2413–14Google Scholar.

58 eg Costa (n 39) 593: ‘By contrast with ordinary international treaties, the EEC Treaty has created its own legal system which, on the entry into force of the Treaty, became an integral part of the legal systems of the Member States and which their courts are bound to apply.’

59 On the misleading character of that dichotomy, see eg Crawford (n 10) 218, pointing out that both terms ‘are more appropriately framed as the ends of a continuum of domestic legal structuring, with much variation in between’.

60 See Spiermann (n 54) 763.

61 de Witte, B, ‘Retour à “Costa”. La primauté du droit communautaire à la lumière du droit international’ (1984) Revue trimestrielle de droit européen 425Google Scholar. cf similarly Crawford (n 10) 241: ‘With European as with international law, the Grundnorm (from the perspective of a national institution) is pacta sunt servanda’.

62 Leben, C, ‘Hans Kelsen and the Advancement of International Law’ (1998) 9 EJIL 297CrossRefGoogle Scholar. See further H Kelsen, Peace through Law (The University of North Carolina Press 1944) 73.

63 Weiler (n 57) 2403.

64 Though only indirectly. See eg the judgment in Essent Belgium, C-204/12 to C-208/12, EU:C:2014:2192, para 51, recalling settled case-law holding that ‘although the Court does not, in a reference for a preliminary ruling, have jurisdiction to give a ruling on the compatibility of a national measure with EU law, it does have jurisdiction to supply the national court with a ruling on the interpretation of EU law so as to enable that court to determine whether such compatibility exists in order to decide the case before it’.

65 Judgment in Bosch, 13/61, EU:C:1962:11, 89.

66 Spiermann (n 54) 773–5.

67 Judgment in Confédération paysanne, C-298/12, EU:C:2013:630, para 37, citing to that effect the judgments in Simmenthal, 106/77, EU:C:1978:49, para 24 and Åkerberg Fransson, C-617/10, EU:C:2013:105, para 45.

68 Judgment in Commission v Italy (‘Premiums for grubbing fruit trees’), 30/72, EU:C:1973:16, para 11. See also the judgment in Commission v Italy (‘Premiums for slaughtering cows’), 39/72, EU:C:1973:13, paras 24–25.

69 Judgment in Internationale Handelsgesellschaft, 11/70, EU:C:1970:114, para 3.

70 Judgment in Commission v Belgium, 77/69, EU:C:1970:34, para 15. See more recently for example the judgment in Commission v Belgium, C-533/11, EU:C:2013:659, in which Belgium was ordered to pay a substantial lump sum as well as a penalty payment on account of a failure by the federated entities to comply with an earlier ECJ judgment and to implement a Directive.

71 eg Judgment in International Fruit Company, 51 to 54/71, EU:C:1971:128, para 3.

72 Opinion of AG Léger in Köbler, C-224/01, EU:C:2003:207, point 88, referring to the Advisory Opinion in Difference Relating to Immunity from Legal Process of a Special Rapporteur of the Commission on Human Rights, ICJ Reports (1998) para 63, where the ICJ held that the conduct of an organ of a State—even an organ independent of the executive power, in casu a court—‘must be regarded as an act of that State’.

73 ibid, point 89, referring to Commission v Belgium (n 70) para 15.

74 Art 49 of the Geneva Convention for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field, 75 UNTS 31; art 50 of the Geneva Convention for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea, 75 UNTS 85; art 129 of the Geneva Convention relative to the Treatment of Prisoners of War, 75 UNTS 135; art 146 of the Geneva Convention relative to the Protection of Civilian Persons in Time of War, 75 UNTS 287. cf Keith, K, ‘“International Law is Part of the Law of the Land”: True or False?’ (2013) 26 LJIL 352CrossRefGoogle Scholar.

75 cf also Elettronica Sicula SPA (ELSI) (Judgment), ICJ Reports (1989) 15, paras 71–73, where the Court responded to an argument by Italy that there was no breach of the relevant treaty because the relevant decision ‘was issued by the competent authority on a regular legal basis’ by patiently explaining that even if the State authority in question had ‘held the requisition to be entirely justified in Italian law, this would not exclude the possibility that it was a violation of the … Treaty’.

76 Applicability of the Obligation to Arbitrate under Section 21 of the United Nations Headquarters Agreement of 26 June 1947 (Advisory Opinion), ICJ Reports (1988) 12, para 57.

77 Nuclear Tests cases (n 18) 268, para 46 and 473, para 49.

78 cf also the Separate Opinion of Judge Ajibola in Territorial Dispute (Libyan Arab Jamahiriya/Chad), (Judgment), ICJ Reports (1994) 6, para 79.

79 UNYBILC (vol II) (1964) 8. For a summary, see Gormley, WP, ‘The Codification of pacta sunt servanda by the International Law Commission: The Preservation of Classical Norms of Moral Force and Good Faith’ (1970) 14 St Louis University Law Journal 367Google Scholar. For an overview of scholarly writings on the matter: R Kolb, La bonne foi en droit international public. Contribution à l’étude des principes généraux de droit (PUF 2000) 93–7. See further H Kelsen, The Law of the United Nations (Praeger 1951) 89 and Zoller (n 11) 338, 351.

80 Gabčíkovo-Nagymaros Project (n 50) 7, para 142. See Koskenniemi (n 51) 588, arguing that the judgment provides an illustration of how sources arguments rotate around the poles of ‘consent’ and ‘justice’.

81 UN Doc A/CONF.39/C.1/L.181.

82 United Nations Conference on the Law of Treaties, Vienna, Austria, First Session, 26 March–24 May 1968, UN Doc A/CONF.39/C.1/SR.72, 72nd meeting of the Committee of the Whole, at 427–428, paras 29–48. See Keith (n 74) 352, arguing that the amendment was added to the text prepared by the ILC to ‘emphasize the pre-eminence of international law over national law’.

83 Draft Declaration on Rights and Duties of States, UNYBILC (1949) 178.

84 Interpretation of the Convention between Greece and Bulgaria respecting reciprocal emigration, signed at Neulilly-sur-Seine on November 27th, 1919, 1930 PCIJ Series B, No 17.

85 Certain German Interests in Polish Upper Silesia (Merits), 1927 PCIJ Series A, No 7, 19. cf in that sense Free Zones of Upper Savoy and the District of Gex (n 18) 12.

86 Treatment of Polish Nationals and Other Persons of Polish Origin or Speech in the Danzig Territory, 1932 PCIJ Series A/B, No 44, 24; cf Greco-Bulgarian ‘Communities’, 1930 PCIJ Series B, No 17, 32.

87 Draft articles on Responsibility of States for Internationally Wrongful Acts, with commentaries (2001) UNYBILC (vol II, Pt 2).

88 LaGrand (Provisional Measures, Order), ICJ Reports (1999) 9, 16, para 28.

89 Leben (n 62) 298.

90 Judgment Inter-Environnement Wallonie, C-129/96, EU:C:1997:628, para 45.

91 ibid para 43.

92 ibid para 41.

93 ibid para 49.

94 ibid para 48. For an illustration, see the judgment in Impact, C-268/06, EU:C:2008:223. There, the ECJ also recalled the loyalty-based principle that national law must be interpreted in conformity with EU law, which requires national courts to do whatever lies within their jurisdiction, taking the whole body of domestic law into consideration and applying the interpretative methods recognized by domestic law, with a view to ensuring that EU law is fully effective and achieving an outcome consistent with the objective pursued by the measure in question: ibid para 101. See the judgment in Von Colson and Kamann, 14/83, EU:C:1984:153, para 26. cf Betlem, G and Nollkaemper, A, ‘Giving Effect to Public International Law and European Community Law before Domestic Courts. A Comparative Analysis of the Practice of Consistent Interpretation’ (2003) 14 EJIL 569CrossRefGoogle Scholar, demonstrating that the differences in application of the principle of consistent interpretation of EU law and international law are a matter of degree not of principle.

95 See further Zoller (n 11) 68ff; Morvay, W, ‘The Obligation of a State Not to Frustrate the Object of a Treaty Prior to its Entry into Force’ (1967) 27 ZaöRV 455Google Scholar.

96 Megalidis (n 53) 386.

97 ibid 395.

98 German Reparations under Article 260 of the Treaty of Versailles (Reparations Commission v Germany), Recueil des Sentences Arbitrales, I, 429, 434–435.

99 ‘If Article 260 referred to the date of entry into force of the Treaty rather than to the date of signature, one would have left the German government with the power to favour the disappearance of the rights and interests that it could cede and thus to regulate the extent of its obligation or even to cancel it, which would be legally impermissible … The German government recognizes that it would be contrary to good faith if, after the signing of the Treaty, it would have taken any measures to transfer the German rights and interests into non-German hands’ (our translation): ibid 522. For the English case report (which omits this passage), see Ann Dig (1923) 341–342.

100 B Cheng, General principles of law as applied by International Courts and Tribunals (Stevens & Sons 1953) 110–11; Morvay (n 95) 455.

101 Certain German Interests in Polish Upper Silesia (Merits) (n 85) 39–40; and see also the connection between good faith and abuse of rights: ibid 38–39 and 42, on which see O Spiermann, International Legal Argument in the Permanent Court of International Justice (CUP 2005) 218.

102 Judgment in Opel Austria v Council, T-115/94, EU:T:1997:3.

103 Council Regulation (EC) No 3697/93 of 20 December 1993 withdrawing tariff concessions in accordance with art 23(2) and art 27(3)(a) of the Free Trade Agreement between the Community and Austria (General Motors Austria), OJ 1993 L343/1.

104 Agreement on the European Economic Area, OJ 1994 L 1/3.

105 Opel Austria (n 102), paras 89–90.

106 ibid paras 93 and 123. cf in that sense PJ Kuijper, ‘Customary International Law, Decisions of International Organisations and Other Techniques for Ensuring Respect for International Legal Rules in European Community Law’ in J Wouters, A Nollkaemper and E de Wet (eds), The Europeanisation of International Law (TMC Asser Press 2008) 94–5.

107 The Court's approach regarding the status of Marpol and UNCLOS in the EU legal order, and in particular its holding (at para 64) that UNCLOS ‘does not establish rules intended to apply directly and immediately to individuals and to confer upon them rights or freedoms capable of being relied upon against States’ has been the subject of much commentary, mostly critical: see eg Eeckhout, P, ‘Case C-308/06, The Queen on the application of Intertanko and Others v Secretary of State for Transport, judgment of the Court of Justice (Grand Chamber) of 3 June 2008, nyr’ (2009) 46 CMLRev 2041–57Google Scholar; Wouters, J and De Man, P, ‘International Association of Independent Tanker Owners (Intertanko), International Association of Dry Cargo Shipowners (Intercargo), Greek Shipping Cooperation Committee, Lloyd's Register and International Salvage Union v Secretary of State for Transport. Case C- 308/06’ (2009) 103 AJIL 555–61Google Scholar.

108 cf also eg the judgments in Kupferberg, 104/81, EU:C:1982:362, para 18 and Sevince, EU:C:1990:322, C-192/89, para 23.

109 Directive 2005/35/EC of the European Parliament and of the Council of 7 September 2005 on ship-source pollution and on the introduction of penalties for infringements, OJ 2005 L255/11.

110 International Convention for the Prevention of Pollution from Ships, 12 ILM 1319 (1973); TIAS No 10,561; 34 UST 3407; 1340 UNTS 184.

111 10 December 1982, 1833 UNTS 3; 21 ILM 1261 (1982).

112 Judgment in Intertanko and Others, C-308/06, EU:C:2008:312, para 52 (emphasis added).

113 EU:C:2010:392.

114 Council Regulation (EEC) 3577/92 of 7 December 1992 applying the principle of freedom to provide services to maritime transport within Member States (maritime cabotage), OJ 1992 L364/7.

115 Judgment in Brita, C-386/08, EU:C:2010:91, paras 40 to 42 and the case law cited there.

116 Judgments in Hurd, 44/84, EU:C:1986:2, para 38; and Commission v Belgium, 52/84, EU:C:1986:3, para 16.

117 Art 4(3), second para, TEU; judgment in My, C-293/03, EU:C:2004:821, para 48. See also art 291(1) TFEU.

118 Judgment in Kortas, C-319/97, EU:C:1999:272, para 35.

119 ibid.

120 Commission v Belgium (n 116) para 16.

121 Judgments in Commission v Belgium (n 116), para 14; Commission v Germany, 94/87, EU:C:1989:46, para 8; Commission v Greece, C-183/91, EU:C:1993:233, para 10; Commission v Italy, C-349/93, EU:C:1995:53, para 12; Commission v Italy, C-348/93, EU:C:1995:95, para 16; Commission v Italy, C-280/95, EU:C:1998:28, para 13; and Commission v Italy, C-6/97, EU:C:1999:251, para 34.

122 Commission v Belgium (n 116), para 16.

123 cf Gabčíkovo-Nagymaros Project (n 50) para 104, referred to by the ECJ in Racke (n 52) para 50.

124 Art 28(4) TEU.

125 Judgment Commission v Belgium, 186/85, EU:C:1987:208, paras 39–40.

126 Judgments in Commission v Luxembourg (n 46) para 60 and Commission v Germany, C-433/03, EU:C:2005:462, para 66.

127 Commission v Luxembourg (n 46) paras 57–66 and Commission v Germany (n 126) paras 64–73.

128 Judgment in Parfums Christian Dior, C-300/98 and C-392/98, EU:C:2000:688, para 36; Mox Plant (n 6) para 175. The ECJ clarified in Commission v Council (n 4) para 55, that the duty of cooperation imposed on the EU and the Member States in the field of mixed agreements cannot justify an institution (here the Council) setting itself free from compliance with the procedural rules and voting arrangements laid down in art 218 TFEU.

129 Mox Plant (n 6) para 176.

130 ibid para 179.

131 ibid para 182 and see also the Opinion of AG Poiares Maduro, EU:C:2006:42, points 57–58.

132 Opinion 2/13 (n 4) para 202.

133 Judgment in Commission v Sweden (‘PFOS’), C-246/07, EU:C:2010:203; on which see further De Baere (n 3).

134 Adopted on 22 May 2001, 40 ILM 532 (2001).

135 Art 193 TFEU.

136 PFOS (n 133), para 102.

137 See Kolb (n 79) 278–9.

138 WTO Appellate Body, United States—Import Prohibition of Shrimp and Certain Shrimp Products (‘Shrimp-Turtle’), WT/DS58/AB/R, para 158; Zoller (n 11) 89.

139 The Islands of Palmas Case (1928), 2 UNRIAA, 829, 839.

140 Trail Smelter Case (1938/1941), 3 UNRIAA, 1965.

141 Annex I to the Report of the United Nations Conference on Environment and Development, held at Rio de Janeiro, 3–14 June 1992, UN Doc A/CONF.151/26 (vol I). See also Principle 27: ‘States and people shall cooperate in good faith and in a spirit of partnership in the fulfilment of the principles embodied in this Declaration and in the further development of international law in the field of sustainable development.’

142 Corfu Channel (Judgment), ICJ Reports (1949) 4.

143 See also eg the fourth principle (‘The duty of States to co-operate with one another in accordance with the Charter’) of the Declaration on Principles of International Law Concerning Friendly Relations and Cooperation among States in Accordance with the Charter of the United Nations (Annex to GA Res 2625 (XXV) of 24 October, 1970, 9 ILM (1970) 1292ff). And see the more specific duties of cooperation in the field of international economic relations listed in Peters, A, ‘International Dispute Settlement: A Network of Cooperational Duties’ (2003) 14 EJIL 2CrossRefGoogle Scholar.

144 Rainbow Warrior (1990), 10 UNRIAA, 217, para 94. See further Kolb (n 79) 280.

145 Separate Opinion of Judge Rezek in Immunity from Legal Process of a Special Rapporteur (n 72) 109. Compare the Opinion of AG Bot in Hungary v Slovakia (n 30), points 58–59. See further the Separate Opinion of Judge Lauterpacht in South-West Africa-Voting Procedure (Advisory Opinion), ICJ Reports (1955) 67.

146 Interpretation of the Agreement of 25 March 1951 between the WHO and Egypt (Advisory Opinion), ICJ Reports (1980) 73.

147 ibid 93 and 95.

148 ibid 95–96.

149 ibid 96.

150 Simma (n 10) 93 (with respect to the UN); G Schwarzenberger, International Law: As Applied by International Courts and Tribunals Volume III (Stevens & Sons 1976) 215.

151 See the references in (n 40).

152 For a recent comparison, see M Klamert (n 40) 55–8.

153 BVerfGE 34, 9 (29).

154 ERTA (n 37) para 22.

155 See art 32(3) GG.

156 BVerfGE 6, 309 (362).

157 BVerfGE 8, 122 (140).

158 Judgments in Commission v Luxembourg and Belgium, 90/63 and 91/63, EU:C:1964:80, 631–632; Hedley Lomas, C-5/94, EU:C:1996:205, para 20; and Commission v Belgium, C-11/95, EU:C:1996:316, paras 37–39.

159 See art 32 GG (‘Relations with foreign states shall be conducted by the Bund’).

160 See below (n 187).

161 Commission v Luxembourg (n 46); Commission v Germany (n 126); PFOS (n 133).

162 Bleckmann, A, ‘Die Anerkennung der Hoheitsakte eines anderen Landes im Bundesstaat’ (1986) Neue Zeitschrift für Verwaltungsrecht, 4Google Scholar.

163 Bauer (n 40) 179.

164 BVerfGE 42, 103 (section 40); BVerwGE 50, 137, (section 44). D Hanschel, Konfliktlösung im Bundesstaat: die Lösung föderaler Kompetenz-, Finanz- und Territorialkonflikte in Deutschland, den USA und der Schweiz (Mohr Siebeck 2012) 78–9.

165 Despite this provision, scholars disagreed about whether the Länder legislatures were merely authorized or under an actual legal duty to pass legislation implementing federal framework legislation adopted pursuant to art 75 GG. As Halberstam notes, scholars such as Hans-Otto Heeger did argue that ‘fidelity to federalism’ implied such a legal duty on the part of the Länder. The disagreement was never resolved by the Constitutional Court—only an amendment of art 75 unequivocally affirmed the obligation to pass implementing legislation. See D Halberstam, ‘Comparative Federalism and the Issue of Commandeering’ in R Howse and K Nicolaidis, The Federal Vision, Levels of Governance, and Legitimacy (OUP 2001) sections 4 and 7. Framework legislation was abandoned as a legislative tool by way of a 2006 amendment of the German Constitution, which deleted art 75 GG in its entirety.

166 BVerfGE 34, 216 (232).

167 See eg RA Lorz, Interorganrespect im Verfassungsrecht (Mohr Siebeck 2001) 33; More nuanced, see Bauer (n 40) 363.

168 BVerfGE 12, 205 (254–255), referring to BVerfGE 6, 309 (328, 361)—which actually merely held that Bundestreue duties of the Länder vis-à-vis the Bund ‘had to be taken very seriously in the area of external relations’, given that the Bund enjoyed a ‘presumption of competence’. Unlike general (customary) international law, international treaties are federal law, because they are incorporated into German law by way of a consent act. In Görgülü, the BVerfG committed Germany to a dualist attitude towards international treaties (BVerfGE 111, 307). See DP Kommers and RA Miller, The Constitutional Jurisprudence of the Federal Republic of Germany (Duke University Press 2012) 310–11.

169 BVerwGE 50, 137, paras 36–50.

170 BVerwGE 50, 137, para 40, referring to BVerfGE 34, 216 (232).

171 BayVerfGH (1975) NJW 1733.

172 See BVerwGE 50, 137, paras 34–35.

173 ibid para 39.

174 ibid para 40.

175 ibid para 43.

176 ibid para 49.

177 I Härtel, Handbuch Europäische Rechtsetzung (Springer 2006) 173–4.

178 See ex art 75 GG.

179 The fact that, for a long time, disagreement existed about whether the Länder legislatures were obligated or merely authorized to pass implementing legislation might have contributed to this. See above (n 165).

180 BVerfGE 1, 299 (315–316).

181 Admission of a State to the United Nations (Advisory Opinion), ICJ Reports (1948) 57.

182 BVerfGE 4, 115 (140).

183 BVerfGE 6, 309 (361); 4, 115 (140).

184 BVerfGE 32, 199 (218); 4, 115 (140). cf similarly ex arts 105 and 107 EEC, which required Member States to treat their exchange policies as a matter of common concern. At the basis of this obligation lay considerations of solidarity based on the loyalty principle: Commission v France (n 196) paras 14–16.

185 See eg BVerfGE 12, 205 (257).

186 See eg BVerfGE 1, 299 (315); 1, 117 (131); 3, 52 (57).

187 BVerfGE 12, 205 (257); 43, 291. To a large extent, this cooperation has now been regulated in legislation. See further Suszycka-Jasch, M and Jasch, H-C, ‘The Participation of the German Länder in Formulating German EU-policy’ (2009) German Law Journal 1215Google Scholar.

188 A similar Bundestreue-based prohibition to discriminate between the Länder was upheld in BVerfGE 84, 148 (271–276), when the Bund favoured one Land over the other in providing emergency assistance.

189 ibid 255.

190 DC Umbach and T Clemens (eds), Grundgesetz: Mitarbeiterkommentar und Handbuch. Band II (CF Müller Verlag 2002) 917.

191 BVerfGE 34, 216 (232).

192 BVerfGE 72, 330 (402).

193 See the holding in Gabčíkovo-Nagymaros Project (n 50) 7, paras 136–142, 155 (‘Finds that Hungary and Slovakia must negotiate in good faith in the light of the prevailing situation’).

194 BVerfGE 1, 117 (131). Although the BVerfG did not refer to Bundestreue but to ‘das bundesstaatliche Prinzip’ (the federal principle), it later referred to the duty in the context of a summary of its Bundestreue case law (see BVerfGE 12, 205 (254)).

195 BVerfGE 86, 148 (258–270). See DP Currie, The Constitution of the Federal Republic of Germany (University of Chicago Press 1994) 80.

196 Judgment in Commission v France, 6 and 11/69, EU:C:1969:68, para 16.

197 The ECJ's loyalty case law has been described as an expression of (a broad conception of) solidarity. See A Marias, ‘Solidarity as an Objective of the European Union and the European Community’ (1994) Legal Issues of Economic Integration 85. Distinguishing loyalty from solidarity, see Klamert (n 40) 35–41.

198 See B Kowalsky, Die Rechtsgrundlagen der Bundestreue (W Blasaditsch 1970) 9–16; and Bauer (n 40) 31.

199 In the first place by the German Constitutional Court, which refers to Smend's seminal contribution (below n 200) as authority for a duty of ‘bundesfreundliches Verhalten’ (BVerfGE 1, 299, para 60; BVerfGE 12, 205, para 169). Bauer (n 40) 49ff has shown that, by contrast to Smend's contribution, earlier formulations of the idea of federal fidelity (inter alia by Bluntschli, von Seyndel and Triepel) are less relevant to its development as a constitutional principle; Kowalsky (n 198) 18ff; Steinberg, R, ‘Grenzüberschreitende Informationsansprüche im Bundesstaat – untersucht am Beispiel des interstaatlichen atomrechtlichen Nachbarrechts’ (1987) Neue Juristische Wochenschrift 2345Google Scholar.

200 R Smend, ‘Ungeschriebenes Verfassungsrecht im monarchischen Bundesstaat’ in X, Festgabe für Otto Mayer: zum siebzigsten Geburtstag (Mohr Siebeck 1916) 247.

201 Smend reacted against the legal positivism of Jellinek and Laband. See A Böhmer, Die Europäische Union im Lichte der Reichsverfassung von 1871. Vom dualistischen zum transnationalen Föderalismus (Duncker & Humblot 1999) 112–13.

202 Smend (n 200) 259, 260. See earlier M von Seydel, Staatsrechtliche und politische Abhandlungen (Akademische Verlagsbuchhandlung von JCB Mohr 1893) 57.

203 See Kowalsky (n 198) 19ff (criticizing Smend on this point).

204 Bauer (n 40) 205–6. This had earlier been argued by Von Seydel (n 202) 57.

205 Smend (n 200) 248.

206 ‘In the diplomatic style of international legal relations’ (our translation): ibid 266.

207 ibid.

208 R Smend, Verfassung und Verfassungsrecht (Duncker & Humblot 1928) 269.

209 See Kowalsky (n 198) 21ff; and see further: A Schüle, Das Problem der einstweiligen Verfügung in der deutschen Reichsstaatsgerichtsbarkeit (C Heymann 1932) 58; C Bilfinger, Einfluß der Einzelstaaten auf die Bildung des Reichswillens (Mohr 1923) 59; G Anschütz and R Thoma, Handbuch des Deutschen Staatsrechts (Mohr 1930) 368; see to a lesser extent also P Laband, Das Staatsrecht des Deutschen Reiches Bd I (Laupp 1911) 107; L Gebhard, Handkommentar zur Verfassung des Deutschen Reiches vom 11. August 1919 (Schweitzer 1932); G Leibholz, Die Gleichheit vor dem Gesetz (CH Beck 1959) 153.

210 BVerfGE 36, 342, para 54; BVerfGE 83, 89, para 31. See U Di Fabio, ‘Der neue Art 23 des Grundgesetzes’ (1993) 32 Der Staat 202.

211 See the judgments above (n 199).

212 ie the Staatsgerichtshof für das Deutsche Reich.

213 German Staatsgerichtshof, 17–18 June 1927, Donauversinkung, RGZ 116, 18, and (1929) 1 ZaöRV 634. For an English summary and a translation of certain relevant fragments, see McCaffrey, SC (Special Rapporteur), ‘Seventh report on the law of the non-navigational uses of international watercourses’ (1991) UNYBILC (vol II(1)) 45, 56–7Google Scholar.

214 Both are now part of the Land Baden-Württemberg.

215 ibid 639. cf BVerfGE 36, 342, para 45.

216 ‘Die allgemeinen Regeln des Völkerrechtes sind Bestandteil des Bundesrechtes. Sie gehen den Gesetzen vor und erzeugen Rechte und Pflichten unmittelbar für die Bewohner des Bundesgebietes.’ (The general rules of international law shall be an integral part of federal law. They shall take precedence over the laws and directly create rights and duties for the inhabitants of the federal territory) (translation by: Prof C Tomuschat and Prof DP Currie, available at <>).

217 ‘The generally accepted rules of the law of nations are to be considered as binding elements of the law of the German Reich’ (our translation).

218 See eg BVerfGE 34, 216 (231).

219 Donauversinkung (n 213) 639. The WSGH went on to hold that the German Länder were still independent States, albeit constrained in their sovereignty by the WRV. However, the legislative power in principle still resided with the Länder (art 6 WRV) and Länder could conclude international treaties with third States (art 78 Abs 2 WRV).

220 ibid 640.

221 ‘A duty for the States of mutual respect and consideration, a duty not to harm one another’ (our translation): ibid.

222 ibid 641.

223 ‘Mutual respect and consideration’ (our translation).

224 ibid 641.

225 ibid.

226 ibid 642.

227 ibid.

228 Territorial Jurisdiction of the International Commission of the River Oder, 1929 PCIJ Series A, No 23, 5–46.

229 In his 1916 contribution, counting 24 pages, he only uses the term in a single paragraph: ibid 267.

230 Smend (n 200) 261, 267.

231 ibid 252.

232 ibid 200, 261.

233 Donauversinkung (n 213) 640–641.

234 Smend (n 200) 250, 251, 265, 266.

235 See further Bauer (n 40) 243–52, developing the argument for Treu und Glauben as the normative basis for the duty of Bundestreue.

236 H Kelsen, Das Problem der Souveränität und die Theorie des Völkerrechts. Beitrag zu einer reinen Rechtslehre (JCB Mohr 1920).

237 Schütze, R, ‘On ‘Federal’ Ground: the European Union as an (Inter)national Phenomenon’ (2009) 46 CMLRev 1069Google Scholar.

238 Spiermann (n 54) 764.

239 See in the German context: H Triepel, Unitarismus und Föderalismus im Deutschen Reich (Mohr 1907) 29. Contra: Smend (n 200).

240 Schütze (n 237) 1089.

241 Livingston, WS, ‘A Note on the Nature of Federalism’ (1952) Political Science Quarterly 88Google Scholar. cf Leben (n 62) 292–3.

242 Shrimp-Turtle (n 138) para 158.

243 Advisory Committee of Jurists, Procès-Verbaux of the Proceedings of the Committee, June 16th–July 24th 1920 with Annexes (Van Langenhuysen Brothers 1920) 335. See also Ripert, G, ‘Les Règles du Droit Civil Applicables aux Rapports Internationaux’ (1933) 44 Recueil des Cours 637Google Scholar. Dworkin, R, ‘A New Philosophy for International Law’ (2013) 41 Philosophy & Public Affairs 20CrossRefGoogle Scholar, considers the principles mentioned in art 38(1)(c) ICJ Statute to be a ‘fossilization’ of a ius gentium of legal principles common to nations as inherited from imperial Rome.

244 cf Schütze, R, ‘Supremacy without Pre-emption? The Very Slowly Emergent Doctrine of Community Pre-emption’ (2006) 43 CMLRev 1048Google Scholar, identifying loyalty as the foundation of pre-emption.

245 cf Rummens, S and Sottiaux, S, ‘Democratic Legitimacy in the Bund or “Federation of States”: the Cases of Belgium and the EU’ (2014) 20 ELJ 568CrossRefGoogle Scholar.

246 N MacCormick, Questioning Sovereignty. Law, State, and Nation in the European Commonwealth (OUP 1999) 135.

247 The President of the Advisory Committee of Jurists, the Belgian Baron Descamps, professor of international law at the University of Leuven, had proposed the phrase ‘the rules of international law as recognised by the legal conscience of civilised nations’ (Advisory Committee of Jurists (n 243) 306). However, this was considered to leave too much scope for judicial discretion, and the final text was adopted as amended on the basis of proposals by Elihu Root (USA) and Lord Phillimore (UK) (ibid 307–351). Further: A Perreau-Saussine, ‘Lauterpacht and Vattel on the Sources of International Law: The Place of Private Law Analogies and General Principles’ in V Chetail and P Haggenmacher (eds), Vattel's International Law from a XXIst Century Perspective/Le Droit International de Vattel vu du XXIe Siècle (Brill 2011) 167–86.

248 Shrimp-Turtle (n 138) para 158.

249 Case concerning rights of nationals of the United States of America in Morocco (n 18) 176, 211–212. In EU law see eg the judgments in Rewe-Zentralfinanz (n 19), para 5; Thieffry (22), para 16; Lord Bruce of Donington, 208/80, EU:C:1981:194, paras 13–14; Asjes and Others, 209 to 213/84, EU:C:1986:188, para 77; Fromme, 54/81, EU:C:1982:142, paras 5–8.

250 Shrimp-Turtle (n 138) paras 158–159.

251 ibid paras 135–142.

252 de la Fayette, L, ‘United States – Import Prohibition of Certain Shrimp and Shrimp Products – Recourse to Article 21.5 of the DSU by Malaysia’ (2002) 96 AJIL 689CrossRefGoogle Scholar.

253 Kishore, P, ‘Revisiting the WTO Shrimps Case in the Light of Current Climate Protectionism: A Developing Country Perspective’ (2012) Journal of Energy and Environmental Law 84Google Scholar.

254 de la Fayette (n 252) 689.

255 WTO Panel, United States—Import Prohibition of Shrimp and Certain Shrimp Products, WT/DS58/RW.

256 Shrimp-Turtle (n 138) para 166ff.

257 ibid para 159. Unsurprisingly, this is also how the German BVerfG summarizes the role of the Bundestreue principle. See eg BVerfGE 32, 199 (114).

258 See Cheng (n 100) 125.

259 Shrimp-Turtle (n 138) paras 168–172.

260 Admission of a State to the United Nations (n 181) 57.

261 Koskenniemi (n 51) 378–9, arguing that the objective and subjective elements used by the ICJ in its interpretation lead to a type of infinite feedback loop without closure. Koskenniemi appears to regard good faith more as a justice-based objective standard, which obscures the unconscious shift between legal and moral obligations: ibid 515, referring to R Unger, Law in Modern Society: Toward a Criticism of Social Theory (Free Press 1976) 214. Similarly, Zoller (n 11) 338–9.

262 Above (n 18) para 39, referring to Border and Transborder Armed Actions (n 18) para 94.

263 Temple Lang (n 19) 76; judgment in Germany v Commission, 8/88, EU:C:1990:241, para 22. The far-reaching duties of abstention imposed on Sweden in PFOS (n 133), though raising the question whether the position that loyalty does not create new obligations under EU law was still tenable (see eg Cremona, M, ‘Case C-246/07, Commission v Sweden (PFOS)’ (2011) 48 CMLRev 1639Google Scholar), can arguably be explained by the particular circumstances of the case (see De Baere (n 3)).

264 Judgment in Deutsche Grammophon, 78/70, EU:C:1971:59, para 5.

265 HP Bull, ‘Vorbemerkungen zu Art. 83 GG’ in R Wasserman (ed), Kommentar zum Grundgesetz für die Bundesrepublik Deutschland 2 (1989) nr 91. Contra: Bauer (n 40) 260.

266 Draft arts on the Law of Treaties with commentaries (1966) UNYBILC (vol II) 218, para 4.

267 cf Van Damme, I, ‘Treaty Interpretation by the WTO Appellate Body’ (2010) 21 EJIL 616–17CrossRefGoogle Scholar.

268 ILC Draft arts (n 266) 211.

269 Van Damme (n 267) 616.

270 ILC Draft arts (n 266) 219, para 5.

271 European Communities – Customs Classification of Frozen Boneless Chicken Cuts, WT/DS269/AB/R, WT/DS286/AB/R, para 197.

272 H Lauterpacht, The Development of International Law by the International Court (Stevens & Sons 1958) 296.

273 Van Damme (n 267) 618.

274 A Aust, Modern Treaty Law and Practice (CUP 2013) 208–9.

275 P Belli, De Re Militari et de Bello Tractatus (1563) (trans HC Nutting, Clarendon Press 1936) 25a.

276 Cheng (n 100) 114.

277 AD McNair, The Law of Treaties (OUP 1961) 365.

278 As mentioned above, in the case law of the ECJ, effectiveness derives from the duty of loyalty. See the judgments in Rewe-Zentralfinanz (n 19) and Comet (n 19), and more recently Commission v United Kingdom (n 33) para 32. See also Neframi (n 3) 326 and Ross, M, ‘Effectiveness in the European legal order(s): beyond supremacy to constitutional proportionality?’ (2006) 31 ELR 476Google Scholar.

279 Lauterpacht (n 272) 296.

280 Van Damme (n 267) 644.

281 ibid 637.

282 Conway (n 3) 141 (with regard to the use of the principle of effectiveness in the case law of the ECJ).

283 de la Fayette (n 252) 289.

284 Agreement Establishing the World Trade Organization (1994), 1867 UNTS 154, 33 ILM 1144.

285 Shrimp-Turtle (n 138) paras 129, 154 and 168.

286 ibid para 172.

287 See the above discussion of the case. The Appellate Body thereby explicitly relied on art 31(3)(c) VCLT. See Shrimp-Turtle (n 138) para 158 (fn 157).

288 cf Dworkin (n 243) 22, offering such an interpretation without, however, mentioning good faith as such.

289 cf Kelsen (n 236) 282–3 (‘Worauf es ankommt, ist nicht, ob der Vertrag eine Rechtsordnung setzt – das tut jeder Vertrag’).