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  • Georg Nolte (a1) and Helmut Philipp Aust (a2)

Issues of State complicity arise ever more frequently in international relations. Rules which deal with the responsibility of States for aiding or assisting in the commission of internationally wrongful acts by other States are, however, not yet fully developed. States frequently support each other's actions without necessarily considering the potential implications of the rules on complicity in international law. This leads to another problem: is support given to another State automatically to be seen as relevant practice for the development of new customary rules or the interpretation of treaties through subsequent practice? Or is it possible for complicit States to play two different roles: to assist in some conduct while not endorsing the legal claim associated with it? This contribution aims to untangle the various facets of complicit State behaviour. It will argue that in some cases, States can indeed play two different roles. States should, however, be careful in considering the long-term implications of such behaviour.

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1 Article 16 of the ILC Articles on State Responsibility: ‘A State which aids or assists another State in the commission of an internationally wrongful act by the latter is responsible for doing so if: (a) That State does so with knowledge of the circumstances of the internationally wrongful act; and (b) The act would be internationally wrongful if committed by that State.’, ILC, ‘Report of the International Law Commission on the Work of its 53rd Session’ (23 April–10 August 2001) UN Doc A/56/10.

2 SR Ratner, ‘Jus ad bellum and jus in bello after September 11’ (2004) 96 AJIL 905, 910.

3 V Lowe, ‘Responsibility for the Conduct of Other States’ (2002) 101 Kokusaiho Gaiko Zassi 1, 10.

4 ‘US Secretly Aids Pakistan in Guarding Nuclear Arms’ New York Times (18 November 2007).

5 ‘Bush Pledges to Help Turkey on Intelligence’ New York Times (6 November 2007); ‘US Helps Turkey Hit Rebel Kurds in Iraq’ Washington Post (18 December 2007).

6 For an assessment of the participation of these States see O Corten, ‘Quels droits et quels devoirs pour les états tiers? Les effets juridiques d'une assistance à une acte d'agression’ in K Bannelier and others (eds), L'intervention en Irak et le droit international (Pedone, Paris, 2004) 104; O Corten, Le droit contre la guerre (Pedone, Paris, 2008) 277–289.

7 Letter dated 19 March 2003 from the Chargé d'affairs a.i. of the Permanent Mission of Malaysia to the United Nations transmitting a statement of the Troika of the Non-Aligned Countries (South Africa, Malaysia, Cuba), UN Doc. A/58/68-S/2003/357 (21 March 2003): The Movement of Non-Aligned Countries represents 116 States. In addition, it is noteworthy that the right to self-defence was not seriously considered in the meeting of the Security Council concerned with the attacks on Iraq, see UN Doc. S/PV.4726 (26 March 2003) and S/PV.4726 (Resumption 1) (27 March 2003); see also the statements made by then UN Secretary General Kofi Annan in a BBC interview on 16 September 2004, available at <> accessed 20 September 2008; and the interpretation made thereof by Spokesman Fred Eckhard, available at <> accessed 20 September 2008. For an in-depth analysis of the discussions within the UN bodies and beyond see O Corten, ‘Opération Iraqi Freedom: Peut-on admettre l'argument de l’ «autorisation implicite» du Conseil de Sécurité?', (2003) 36 RBDI 205; for scholarly rejections of the claim to self-defence see TM Franck, ‘What Happens Now? The United Nations After Iraq’ (2003) 97 AJIL 607, 611; AL Paulus, ‘The War Against Iraq and the Future of International Law: Hegemony or Pluralism?’ (2003) 25 Michigan J Int L 691; C Tomuschat, ‘Iraq—Demise of International Law?’, (2003) 78 Die Friedens-Warte 141; for the most straightforward rejection see V Lowe, ‘The Iraq Crisis: What Now?’ (2003) 52 ICLQ 859, 865: ‘There is no arguable case that the United States and the United Kingdom were acting in self-defence in invading Iraq.’ For various versions to legitimate the legality of the attacks on Iraq see the expertise of Lord Goldsmith first gave to the British Government on 7 March 2003, available at <> accessed 20 September 2008; C Greenwood, ‘The Legality of Using Force Against Iraq’, Memorandum of 24 October 2002, available at <> accessed 20 September 2008; Y Dinstein, War, Aggression, and Self-Defence (4th edn, OUP, Oxford, 2005) 297; WH Taft IV/TF Buchwald, ‘Preemption, Iraq and International Law’, (2003) 97 AJIL 557; R Wedgwood, ‘The Fall of Saddam Hussein: Security Council Mandates and Preemptive Self-Defense’ (2003) 97 AJIL 576.

8 Cf JA Frowein, ‘Is Public International Law Dead?’ (2003) 46 GYIL 9, 11; TM Franck (n 7) 611, holds the authorization thesis to be ‘more sophisticated that the plea to have acted in self-defence’ which, in turn, was ‘hard to fit within any plausible theory of imminence’; JE Stromseth, ‘Law and Force After Iraq: A Transitional Moment’ (2003) 97 AJIL 628, 630: ‘(…) the text of Resolution 1441 can fairly be read as an agreement to disagree over whether an additional Security Council Resolution authorizing force was needed in the event of Iraqi non-compliance.’; P Sands, Lawless World (Paperback Edition, Penguin Press, London, 2006) 269 on the first legal advice by Lord Goldsmith to the British Government: ‘As much as I disagree with the equivocal conclusion of the Attorney's 7 March advice, I accept that the document as a whole is careful, balanced and reasonable.’ Other international lawyers have left the zone of the arguable, eg J Yoo, ‘International Law and the War in Iraq’ (2003) 97 AJIL 563.

9 Currently, a parliamentary committee of the Bundestag investigates issues in connection with the German participation in the war against Iraq, see <> accessed 20 September 2008, German language only; for the Report of the Federal Government see <> accessed 20 September 2008.

10 N Ronzitti, ‘Italy's Non-Belligerency During the Iraq-War’, in M Ragazzi (ed), International Responsibility Today—Essays in Memory of Oscar Schachter (Nijhoff, Leiden/Boston 2005) 197, 201.

11 See the speech of Bundeskanzler Gerhard Schröder at the Bundestag on 19 March 2003, Bulletin 24–3 of 19 March 2003, cited in M Hartwig, Völkerrechtliche Praxis der Bundesrepublik Deutschland im Jahr 2003, 65 (2005) ZaöRV, 741, 775.

12 O Corten, ‘Les arguments avancés par la Belgique pour justifier son soutien aux Etats-Unis dans le cadre de la guerre contre l'Irak’ (2005) 38 RBDI 417, with the text of the ‘Agreement Between Belgium and the United States Concerning the Preparation and Operation of an American Line of Communication in Belgium’ of 16 and 19 July 1971 reprinted at 440–446.

13 The Canadian approach should be differentiated from the example of Belgium. The Belgian government was strictly opposed to the legality of attacks on Iraq before the commencement of the armed conflict but was anxious afterwards to shift the focus from the legality to the legitimacy of the attacks, arguing inter alia that there are different positions concerning legality; see for the different positions E David, ‘La pratique du pouvoir exécutive et le contrôle des chambres législatives en matière de droit international (1999–2003)’ (2005) 38 RBDI 5, 264–265.

14 Hansard of the Canadian Parliament of 17 and 18 March 2003, available at <> and <> respectively, accessed 20 September 2008).

15 Case Concerning the Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgment) 2007 <> accessed 20 September 2008, para 419; for a concise summary of the judgment see S Sivakumaran, Case Note, (2007) 56 ICLQ 695.

16 See, eg V Lowe, International Law (OUP, Oxford, 2007) 121.

17 R Ago, ‘Seventh Report on State Responsibility’, UN Doc. A/CN.4/307 and Add. 1 and 2, YBILC 1978, Vol. II, pt. one, 31, 58–60.

18 GA Res 56/83 (12 December 2001).

19 Definition of Aggression, GA Res. 3314 (XXIX) (14 December 1974). Possible other primary obligations can arise out of the laws of neutrality. Their application is, however, dependent on a declaration of neutrality. For the continued relevance of the law of neutrality see Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion) ICJ Rep 1996 261; see also UK Ministry of Defence (ed), The Manual of the Law of Armed Conflict (OUP, Oxford, 2004), para 1.43; I Brownlie, International Law and the Use of Force by States (Clarendon Press, Oxford, 1963) 404; Y Dinstein (n 7) 163; C Greenwood, ‘The Concept of War in Modern International Law’ (1987) 36 ICLQ 283.

20 The Definition of Aggression is not only concerned with elucidating the term as it appears in Article 39 of the UN Charter, but also whether an armed attack has been committed and/or whether Article 2 (4) of the Charter has been violated, see for example Armed Activities in and Against Nicaragua (Nicaragua v The United States of America) (Judgment, Merits) (1986) [1986] ICJ Rep 14, para 195.

21 On the genesis of and limits to the binary code of law see N Luhmann, Das Recht der Gesellschaft (Suhrkamp, Frankfurt/M. 1993) 165. In this context one can also refer to the ‘penumbra of uncertainty’ which is said to surround every legal rule, HLA Hart, The Concept of Law (2nd edn, OUP, Oxford, 1994) 12.

22 Case Concerning the Application of the Convention on the Prevention and Punishment of Genocide (n 15), para 420.

23 Roberto Ago, Seventh Report on State Responsibility, YBILC 1978, Vol. II, Pt. one, 52 et seq and James Crawford, Second Report of State Responsibility, UN Doc. A/CN./498/Add. 1 respectively.

24 ILC Commentary to Article 16, reprinted in J Crawford (ed), The International Law Commission's Articles on State Responsibility (CUP, Cambridge, 2002) Art 16, para 7.

25 ibid, para 8.

26 ibid, para 9.

27 ibid.

28 See above (n 19).

29 ILC Commentary (n 24) Article 16, para 2.

30 Sceptical in this regard A Orakhelashvili, Peremptory Norms in International Law (OUP, Oxford, 2006) 80; see with further references HP Aust, ‘Through the Prism of Diversity—The Articles on State Responsibility in the Light of the ILC Fragmentation Report’ (2006) 49 GYIL, 165, 175–177; in this regard, Roberto Ago made an interesting remark: Answering the question just described whether the draft provision would not leap the barrier between primary and secondary rules he responded that ‘in his opinion the Commission should not hesitate to leap that barrier whenever necessary.’, R Ago, Statement at the 1519th Meeting of the ILC, YBILC 1978, Vol. I, 240, para 27. Given the importance that Ago generally assigned to the distinction between primary and secondary rules in general this may come as a surprise, see R Ago, ‘Working Paper on State Responsibility’, YBILC 1963, Vol. II, 251–254: ‘… any discussion of international responsibility should take into account the whole of responsibility and nothing but responsibility’; ibid, 253.

31 Support was, among others, expressed by Finland, UN Doc. A/C.6/33/SR.39, para. 4; Mali, YBILC 1980, Vol. II, Pt. one, 101; Mexico, UN Doc. A/C.6/55/SR. 20, para. 42; the Netherlands, UN Doc. A/CN.4/515, 28; Japan, UN Doc. A/C.6/54/SR.22, para 8; the United Kingdom, the United States of America, UN Doc. A/CN.4/488, 75 et seq.

32 These governments include Germany and Switzerland, see UN Doc. A/CN.4/488, at 75 et seq; Switzerland's position is however compromised by a later statement, UN Doc. A/C.6/54/SR.22, para 70 et seq, in which the complicity provision has been commented on a in more favourable light. Its status as a rule of customary international law has also been questioned by the Federal Republic of Yugoslavia in the Case Concerning Application of the Convention on the Prevention and Punishment of the Crime of Genocide (n 15), Counter-Memorial of 22 July 1997, 336, <> accessed 20 September 2008.

33 For the customary law status cf J Quigley, ‘Complicity in International Law: A New Direction in the Law of State Responsibility’ (1986) 57 BYIL 77; B Graefrath, ‘Complicity in the Law of International Responsibility’ (1996) 29 RBDI 370; K Nahapetian, ‘Confronting State Complicity in International Law’, (2002) 7 UCLA Journal of International Law and Foreign Affairs 99; A Boivin, ‘Complicity and beyond: International law and the transfer of small arms and light weapons’ (2005) (859) 87 IRRC, 467; S Talmon, ‘A Plurality of Responsible Actors? International Responsibility for Acts of the Coalition Provisional Authority in Iraq’, in Phil Shiner and Andrew Williams (eds), The Iraq War and International Law, (Hart, Oxford, 2008) forthcoming, <> accessed 20 September 2008, 31 of the manuscript; for a sceptical view see E Klein, ‘Beihilfe zum völkerrechtlichen Delikt’, in Ingo von Münch (ed), Staatsrecht—Völkerrecht—Europarecht: Festschrift für Hans-Jürgen Schlochauer, (de Gruyter, Berlin 1981), 425; unsure whether the ILC has succeeded in proving the existence of such a norm CJ Tams, ‘All's Well That Ends Well—Comments on the ILC's Articles on State Responsibility’, (2002) 62 ZaöRV, 759, 794; for an overview on the treatment of complicity in the literature see A Felder, Die Beihilfe im Recht der völkerrechtlichen Staatenverantwortlichkeit, (Schulthess, Zürich 2007) 236–237.

34 See above (n 15).

35 See the pleading of Alain Pellet on behalf of Bosnia and Herzegovina in the Case Concerning Application of the Convention on the Prevention and Punishment of Genocide (n 15) CR 2006/8, 28. While denying the pertinence of Article 16 of the ILC Articles for the said case, Ian Brownlie and Natasja Fauveau-Ivanovíc on behalf of Serbia and Montenegro do not deny its status as a customary norm, CR 2006/40, 50–51 and CR 2006/43, 63–65 respectively, all available at <> accessed 20 September 2008.

36 Venice Commission of the Council of Europe: Opinion on the International Legal Obligations of Council of Europe member states in respect of secret detention facilities and inter-state transport of prisoners, CDL-AD(2006)009, para 45, reprinted in (2006) 27 HRLJ 122.

37 P Bernard, ‘Le Rwanda publie son réquisitoire contre la France’ Le Monde (6 August 2008); see also R Dallaire/K Manocha/N Degnarain, ‘The Major Powers on Trial’ (2005) 3 JICJ 861; F Grünfeld/A Huijboom, The Failure to Prevent Genocide in Rwanda—The Role of Bystanders, (Transnational, New York, 2007).

38 ‘Inquiry Opened Into Israeli Use of U.S. Bombs’ New York Times (25 August 2006) <> accessed 20 September 2008; ‘Israel May Have Violated Arms Pact, U.S. Official Says’ New York Times (28 January 2007, Section 1, Column 1, 3).

39 BVerfGE 109, 13, 26–27—Extradition of a Person Lured out of its Home Country, see on this judgment M Hartwig, Case Note, ILDC 10 (DE 2003), <> accessed 20 September 2008.

40 BVerwG 2 WD 12.04—Pfaff, judgment of 21 June 2005, available at <> accessed 20 September 2008, see on this judgment HP Aust, Case Note, ILDC 483 (DE 2005), <> accessed 20 September 2008, with an English translation of the relevant parts of the judgment; and I Baudisch, Case Note, (2006) 100 AJIL 911.

41 The content of the note and the UK response can be read out of several newspaper articles in which a UK government spokesman affirms the existence of the protest but denies all responsibility by the UK, see ‘Dam Backed by Blair Flouts International Law, Syria Says’ The Independent (16 July 2000, 10); and the article by H Elver, ‘World Commission on Dams Report Challenges Financing for Ilisu Dam’ Turkish Daily News (20 March 2001, available at lexisnexis). It is indeed possible that this project violates obligations arising from international environmental law, human rights law and the rules on the protection of cultural heritage, see J McCrystie Adams, ‘Environmental and Human Rights Objections Stall Turkey's Proposed Ilisu Dam’ (2000) Colorado J Int Env L and Pol, 173; K Wangkeo, ‘Monumental Challenges: The Lawfulness of Destroying Cultural Heritage During Peacetime’, (2003) 28 Yale Int L J 183.

42 ‘Turkey Dam Violates Law Says Arab League’ Gulf Daily News (18 July 2000, available at lexisnexis).

43 Omissions are particularly difficult to deal with. The ICJ has now ruled out the possibility of complicity by omission in its Genocide Convention Case (n 15) para 432. This is not wholly convincing, however. In the case of overflights it is not only possible that a State explicitly grants such rights, but also that it simply does not object to the use of its airspace. Although the conduct attributable to a State can, in principle, consist of acts as well as omissions (Article 2 of the ILC Articles), complicity by a omission is only conceivable a duty to act is incumbent on the helping State, see A Felder (n 33) 254–255; S Sivakumaran (n 15) 704–705.

44 C Chinkin, Third Parties in International Law (Clarendon Press, Oxford, 1993) 297; V Lowe (n 3) 5; A Felder (n 33) 250; contra: S Talmon (n 33) 30–31.

45 A Epiney, ‘Nachbarrechtliche Pflichten im internationalen Wasserrecht und Implikationen für Drittstaaten’, (2001) 39 AVR, 1; A Epiney, ‘Umweltvölkerrechtliche Rahmenbedingungen für Entwicklungsprojekte’ (2005) 41 BDGVR 329, 358.

46 ‘Türkisches Ultimatum—Deutschland muss über Kreditgarantie für Staudamm entscheiden’ Frankfurter Allgemeine Zeitung (1 March 2007, 5); ‘Staudamm-Projekt bereitet Berlin Bauchschmerzen’ Frankfurter Rundschau (9 March 2007, 12).

47 ‘Bedingte Zustimmung zu Ilisu-Staudamm—Bundesrat gewährt Exportrisikogarantie unter Auflagen’ Neue Zürcher Zeitung (16 December 2006, <> accessed 20 September 2008); Press Release of the German Ministry for Economic Affairs of 26 March 2007, <,did=193686.html>accessed 20 September 2008.

48 See the statement of the Iraqi Minister for Water Affairs, ‘Türkei—Lässt Damm den Irak austrocknen?’ Die Presse (4 May 2007).

49 Although one could think that now this problem is solved, mention must be made that after the granting of the export credit guarantee the Iraqi Government has denied any change of position on its side on the matter, see the recent survey of the NGOs ‘The Corner House’ and ‘The Kurdish Human Rights Project’, available at <> accessed 20 September 2008.

50 See also V Lowe (n 3) 6.

51 Articles 5, 8 and 11 et seq of the UN Convention on the Non-Navigational Uses of International Waterways which stipulates a duty of cooperation, GA Res. 51/229, annex of 21 May 1997. The Convention has not yet entered into force, but is considered as representing customary international law for the most part, see A Tanzi/M Arcari, The United Nations Convention on the Law of International Watercourses—A Framework for Sharing (Kluwer, London, 2001) 89.

52 Affaire du Lac Lanoux (Spain v France) (1957), 12 RIAA 281, 315; cf H Elver, Peaceful Uses of International Rivers—The Euphrates and Tigris River Disputes (Transnational, Ardsley, 2002) 211; generally on the procedural aspects see SC McCaffrey, The Law of International Watercourses—Non-Navigational Uses (OUP, Oxford, 2001) 341.

53 In 1980, a ‘Joint Technical Committee’ of Turkey and Iraq was founded which was later on joined by Syria, see H Elver (n 52) 407.

54 A related issue was briefly discussed in the ILC in the course of the Second Reading of the Draft Articles on State Responsibility. John Dugard held that the State which was to be held responsible for complicity ‘must indeed have knowledge not merely of the circumstances of the act but also of its wrongfulness.’ Statement at the 2577th Meeting of the ILC, YBILC 1999, Vol. I, 69, para 13. Otherwise, however, the issue was discussed under the rubric of ‘ignorance of the law’ which was rightly rejected as an excuse for responsibility of the assisting State, cf. James Crawford, ibid, para 14.

55 V Lowe (n 3) 10.

56 ibid.

57 ILC Commentary (n 24), Introduction to Part one, Chapter IV, para 9.

58 Cf R Ago, ‘Seventh Report on State Responsibility’, YBILC 1978, Vol. II, pt. one, 30, 55, para 63: ‘The decision of a sovereign State to adopt a certain course of conduct is certainly its own decision, even if it has received suggestions and advice from another State, which it was at liberty not to follow.’; see also the Dissenting Opinion of Judge Schwebel, Military and Paramilitary Activities in and against Nicaragua (n 20) 388–389.

59 R Ago, ‘Seventh Report on State Responsibility’, YBILC 1978, Vol. II, pt. one, 52, para 52.

60 ILC Commentary (n 24) Art 16, para 3.

61 On the issue of fault in the law of State responsibility see A Gattini, ‘Smoking/No-Smoking’ : Some Remarks on the Current Place of Fault in the ILC Draft Articles on State Responsibility' (1999) 10 EJIL 397.

62 J Crawford (n 24) 12.

63 Similarly A Boivin (n 33) 471.

64 Case Concerning the Application of the Convention on the Prevention and Punishment of Genocide (n 15) paras 420–424; one should however not lose sight of the fact that the Court dealt with an issue relating to the Genocide Convention. ‘Inter-state’ complicity was only used by way of analogy, all pronouncements of the Court on complicity therefore need to be assessed with caution.

65 On the way the Court made use of Article 16 see A Cassese, ‘On the Use of Criminal Law Notions in Determining State Responsibility for Genocide’ (2007) 5 JICJ 875, 881–882; PM Dupuy, ‘Crime sans chatiment ou mission accomplie?’ (2007) 111 RGDIP 243, 247; P Weckel, ‘L'arrêt sur le genocide: Le souffle de l'avis de 1951 n'a pas transporté la Cour’ (2007) 111 RGDIP 305, 322–324.

66 Case Concerning the Application of the Convention on the Prevention and Punishment of Genocide (n 15) para 421.

67 See the comments of the governments of Denmark (also on behalf of Finland, Iceland, Norway, Sweden), Republic of Korea and the United States of America, UN Doc. A/CN.4/515, 27.

68 It has sometimes been questioned whether the intent requirement is hindering the effective application of the complicity provision, see only A Felder (n 33) 261; B Graefrath (n 33) 375; K Nahapetian (n 33) 106; J Quigley (n 33) 109; S I Skogly, Beyond National Borders: States' Human Rights Obligations in International Cooperation (Intersentia, Antwerp, 2006) 38–39 since it would be difficult to prove the intent of a State to assist the internationally wrongful act of another State, cf B Simma, ‘Grundfragen der Staatenverantwortlichkeit in der Arbeit der International Law Commission’ (1986) 24 AVR 357, 380. However, the criteria for establishing responsibility and the standards of evidence are two different issues. The possibility of inferring intent and/or knowledge on the side of the complicit State from factual circumstances is not to be underestimated.

69 On due diligence see in general R Pisillo-Mazzeschi, ‘The Due Diligence Rule and the Nature of the International Responsibility of States’ (1992) 35 GYIL 1.

70 Talmon holds the view that such a standard might develop in the future, S Talmon (n 33) 32.

71 See on this issue S Oeter, Neutralität und Waffenhandel (Springer, Berlin, 1992), passim.

72 Section 2754 of the US Arms Export Control Act, 22 U.S.C. 2278; § 34 of the German Außenwirtschaftsgesetz (Foreign Trade Law) provides for criminal responsibility for those who export military materiel in a way which is likely to endanger peace in international relations; see also the Wassenaar arrangement of 12 July 1996, <> accessed 20 September 2008, to which more than 30 States adhere to, but which does not represent a binding international instrument.

73 For an example of a very doubtful case in this respect see M Bothe/T Lohmann, ‘Der türkische Einmarsch in den Nordirak—Neue Probleme des völkerrechtlichen Gewaltverbots’, (1995) 5 SZIER 441, 453 (concerning a Turkish guarantee not to use military material delivered by Germany).

74 See similarly J Künzli, Vom Umgang des Rechtsstaats mit Unrechtsregimes—Völker- und landesrechtliche Grenzen des Verhaltensspielraums der schweizerischen Außenpolitik gegenüber Völkerrecht missachtenden Staaten (Stämpfli, Bern, 2008) 414.

75 TM Franck, Fairness in International Law and Institutions (OUP, Oxford, 1995) 30–31.

76 The scope of application of Article 41, para 2 is not easy to determine. Generally, it applies ‘after the fact’ while being applicable regardless of whether the internationally wrongful act is continuing or not, see ILC Commentary (n 24), Article 41, para 11.

77 ibid. It needs to be awaited, however, how the recent findings of the Genocide Convention Case on the standards of evidence for ‘claims (…) involving charges of exceptional gravity’ will affect this question, see (n 15) paras 209–230, cf A Gattini, ‘Evidentiary Issues in the ICJ's Genocide Judgment’ (2007) 5 JICJ 889.

78 For the field of international humanitarian law see M Brehm, ‘The Arms Trade and States’ Duty to Ensure Respect for Humanitarian and Human Rights Law' (2007) 12 JCSL, 359, 386.

79 It is a matter of debate whether the obligation of non-refoulement is dealing with complicity. While some deny it for the lack of specific connection between the expulsion and the subsequent torture, cf A Felder (n 33) 133, there are conceivable scenarios in which complicity and non-refoulement overlap, eg the scenario of extraordinary rendition in which a person is handed over precisely for the purpose of being subjected to torture.

80 Article 3 of the United Nations Convention Against Torture speaks of ‘substantial grounds for believing’ that the person extradited would be in danger of being subjected to torture.

81 J Allain, ‘The Jus Cogens Nature of Non-Refoulement’ (2001) 13 IJRL 553, 557–558.

82 E de Wet, ‘The Emergence of International and Regional Value Systems as a Manifestation of the Emerging International Constitutional Order’ (2006) 19 LJIL 611, 616–617; AL Paulus, ‘Jus Cogens in a Time of Hegemony and Fragmentation’ (2005) 74 Nordic J Int L 297, 333; with particular emphasis on complicity J Howard, ‘Invoking State Responsibility for Aiding the Commission of International Crimes—Australia, the United States and the Question of East Timor’ (2001) 2 Melbourne J Int L 1, <> accessed 20 September 2008.

83 ILC Commentary (n 24) Article 41, para 11; A de Hoogh, Obligation Erga Omnes and International Crimes—A Theoretical Inquiry into the Implementation and Enforcement of the International Responsibility of States (Nijhoff, The Hague 1996) 161; A de Hoogh, ‘Australia and East Timor—Rights Erga Omnes, Complicity and Non-Recognition’ (1999) Australian Int L J 63; see generally on the importance of the clarity of peremptory norms G Nolte, ‘Universal Jurisdiction in the Area of Private Law—The Alien Tort Claims Act’, in C Tomuschat/JM Thouvenin (eds), The Fundamental Rules of the International Legal Order (Nijhoff, The Hague 2006) 373.

84 ILC Commentary (n 24) Article 41, para 11.

85 On the contours of the obligation to prevent genocide in another State's territory see now Case Concerning the Application of the Convention on the Prevention and Punishment of Genocide (n 15) paras 428–438; for a critical assessment of the Court's findings in this regard A Gattini, ‘Breach of the Obligation to Prevent and Reparation Thereof in the ICJ's Genocide Judgment’ (2007) 18 EJIL 695; S Sivakumaran (n 15) 705; see also A Cassese, ‘A Judicial Massacre’ The Guardian (27 February 2007, <> accessed 20 September 2008, referring to the finding of the breach of the obligation to prevent genocide as a ‘consolation prize’).

86 See the contributions referred to above (n 7).

87 See also V Lowe (n 3) 11.

88 Some States tried to assert that no new guarantees for over-flight rights were given in the context of the War on Iraq; see, eg for Italy the statement of the Minister for the Relationships with the Parliament of 26 February 2003 at the Chamber of Deputies, reprinted in: L Appicciafouco and others, ‘Italian Practice Relating to International Law—Diplomatic and Parliamentary Practice’ (2003) 13 Italian Y Int L 265, 287.

89 For a comprehensive survey see JM Sorel, ‘Commentaire de l'Article 31’, in O Corten/P Klein (eds), Les Conventions de Vienne sur le droit des traités— Commentaire article par article (Bruylant, Bruxelles, 2006); W Karl, Völkerrechtlicher Vertrag und nachfolgende Praxis (Springer, Berlin, 1983); see also G Nolte, ‘Treaties over time, in particular: subsequent practice and subsequent agreement’, Report of the International Law Commission on its Sixtieth Session (2008), UN Doc. A/63/10, Annex A.

90 The National Security Strategy of the United States of America, September 2002, available at <> accessed 20 September 2008.

91 Cf Military and Paramilitary Activities in and Against Nicaragua (n 20) para 208.

92 But see Dinstein, Y, ‘Customary International Law and Treaties’ (2006) 322 Recueil des Cours de l'Académie de Droit International 243, 276277, who focuses on States which practise a ‘double standard’, ie carrying out conduct in one manner and urging another State to pursue an altogether different path in parallel circumstances, ibid. This situation is arguably different from the one we are discussing.

93 For an overview on this discussion see AE Roberts, ‘Traditional and Modern Approaches to Customary International Law: A Reconciliation’ (2001) 95 AJIL 757; A Seibert-Fohr, ‘Unity and Diversity in the Formation and Relevance of Customary International Law—Modern Concepts of Customary International Law as a Manifestation of a Value-Based International Order’, in A Zimmermann/R Hofmann (eds), Unity and Diversity in International Law (Duncker & Humblot, Berlin, 2006) 257.

94 And it is the simultaneous character of statement and practice which distinguishes our case from the one in which a State first contributes practice to the development of new customary law or to the interpretation of a treaty and subsequently changes its position in order to rid itself from its previous practice. While the scenarios of subsequent practice and statements can also arise in situations of complicity, they are not our main interest.

95 W Karl, ‘Protest’, in R Bernhardt (ed), Encyclopedia of Public International Law, Vol III (Elsevier, Amsterdam, 1997) 1157, 1158; IC MacGibbon, ‘Some Observations on the Part of Protest in International Law’, (1953) 30 BYIL 293, 312; I Breutz, Der Protest im Völkerrecht (Duncker & Humblot, Berlin, 1997) 108.

96 Island of Palmas Case (The Netherlands v United States of America) (1928), 2 RIAA, 829, 839; on this arbitration see DE Khan, ‘Max Huber as Arbitrator: The Palmas (Miangas) Case and Other Arbitrations’ (2007) 18 EJIL 145, 158.

97 A D'Amato, The Concept of Custom in International Law (Cornell University Press, Ithaca, 1971) 98.

98 Fisheries Case (United Kingdom v Norway), (Judgment) (1951) [1951] ICJ Rep 1951, 116, 191; for a similar position concerning, however, a dispute over title to territory see The Minquiers and Ecrehos Case (France v United Kingdom) (Judgment) (1953) [1953] ICJ rep 1953, 47, ind. op. of Judge Carneiros, ibid 85.

99 MH Mendelson, ‘The Formation of Customary International Law’ (1998) 272; Recueil des Cours de l'Académie de Droit International 155, 205; a great variety of scholarly writings discusses the impact of protest without referring to the problem of ‘paper protests’; see, eg M Akehurst, ‘Custom as a Source of International Law’, (1974–1975) 47 BYIL 1, 38; K Wolfke, Custom in Present International Law (2nd edn, Nijhoff, Dordrecht, 1993), 56; MS McDougal, ‘The Hydrogen Bomb Tests and the International Law of the Sea’ (1955) 49 AJIL 356, 357; IC MacGibbon, ‘Customary International Law and Acquiescence’ (1957) 33 BYIL 115, 118; I Breutz (n 95) 127–128.

100 The Case of the S.S. Lotus (France v Turkey) (Judgment) (1927) Series A, No. 10, 29.

101 M Akehurst (n 99) 41.

102 It has been pointed out that to neglect the importance of statements and protests for the development of customary rules means to deprive less powerful States of influence as they are most likely not able to contribute material practice, see M Byers, Custom, Power and the Power of Rules (CUP, Cambridge, 1999) 134; B Stern, ‘La coutume au cœur du droit international’, in: Mélanges offerts à Paul Reuter (Pedone, Paris, 1981) 479.

103 JP Müller/T Cottier, ‘Acquiescence’, in Rudolf Bernhardt (ed), Encyclopedia of Public International Law, Vol I (Elsevier, Amsterdam, 1992) 14–16.

104 Case Concerning Delimitation of the Maritime Boundary in the Gulf of Maine Area (Canada v United States of America) (Judgment) (1984) ICJ Rep 246, para 130.

105 Case Concerning the Temple of Preah Vihear (Cambodia v Thailand) (Judgment, Merits) (1962) [1962] ICJ Rep 6, sep. op. Judge Alfaro, ibid 39, 40.

106 M Akehurst (n 99) 39.

107 Gulf of Maine (n 104) para 130.

108 ibid; see also H Das, ‘L'Estoppel et l'Acquiescement: Assimilations Pragmatiques et Divergences Conceptuelles’ (1997) 30 RBDI 607, 608; MN Shaw, International Law (5th edn, CUP, Cambridge, 2003) 439 and M Koskenniemi, From Apology to Utopia—The Structure of International Legal Argument (Reissue, CUP, Cambridge, 2005) 356 who also has difficulties in identifying substantial differences and seems to argue that one and the same situation can be characterised by both acquiescence and estoppel.

109 See Temple of Preah Vihear (n 105), sep. op. Judge Fitzmaurice, 61 who emphasizes the theoretical distinctiveness of the two principles.

110 JP Müller/T Cottier, ‘Estoppel’, in Rudolf Bernhard (ed), Encyclopedia of Public International Law, Vol. II (Elsevier, Amsterdam, 1995) 116; Brownlie has pointed out that estoppel is regarded with great caution in domestic legal systems and that the principle has no particularly coherent image in international law, see I Brownlie, Principles of Public International Law (6th edn, OUP, Oxford, 2003) 616; see also PCW Chan, ‘Acquiescence/Estoppel in International Boundaries: Temple of Preah Vihear Revisited’ (2004) 3 Chinese J Int L 421, 439.

111 North Sea Continental Shelf Cases (Federal Republic of Germany v. Denmark; Federal Republic of Germany v The Netherlands) (Judgment) (1969) [1969] ICJ Rep 4, para 30.

112 As to common law systems see AT von Meeren in International Encyclopedia of Comparative Law, Volume VII—Contracts in General, Chapter 9: The Formation of Contracts, (Mohr Siebeck, Tübingen et al, 1992) 15, who discusses the principle with reference to the German doctrine of the factual entrance into treaties. The principle of protestatio facto contraria non valet is not mentioned in the leading treatise on English contract law: Sir G Treitel, The Law of Contract (11th edn, Sweet & Maxwell, London, 1999). For an isolated account in Anglo-American scholarship see N L, ‘The Theory of Implied Contracts’ (1856) 4 The American Law Register, 321, 325 referring to the case of Walker v The York and Midland Railway Company, 2 E. & B. 750. Common law systems seem to deal with this issue by way of various emanations of the principle of estoppel. For an overview on the various meanings of estoppel see G Spencer Bower/Sir A Kingcome Turner, The Law Relating to Estoppel by Representation (2nd edn, Butterworth, London, 1966) especially at 3, 12, 261 and 332.

113 See for Italy the sceptical account of R Giampetraglia, Protestatio contra factum non valet. Fondamenta, Rilevanzi, Limiti (Liguori, Naples, 2000); for France see PY Gautier, ‘Le non-vouloir dans les documents non-contractuels: où la Cour de Cassation perd une occasion d'appliquer l'adage “Protetatio non valet contra actum”’ (2001); Rev Trim Dr Civ 904 (commenting on an unreported decision of the 3rd Civil Chamber of the Cour de Cassation of 21 March 2001).

114 Article 1.8: ‘A party cannot act inconsistenly with an understanding it has caused the other party to have and upon which that other party reasonably has acted in reliance to its detriment’ in Unidroit (ed), Unidroit Principles of International Commercial Contracts (Unidroit, Rome, 2004).

115 PY Gautier (n 113) 905–906 with further references to French literature.

116 For vigorous criticism see H Köhler, ‘Kritik der Regel “protestatio facto contraria non valet”’ (1981) JZ 464; this interpretation is widely supported, see only D Medicus, Bürgerliches Recht (20th edn, Heymanns, Köln, 2004) 134–135; EA Kramer, Vorbemerkung zu §§ 116–124 BGB, para 40, in Münchener Kommentar zum Bürgerlichen Gesetzbuch (5th edn, CH Beck, München, 2006); for the opposite view which favours a broader scope of application see K Larenz/M Wolf, Allgemeiner Teil des Bürgerlichen Rechts (9th edn, CH Beck, München 2004) 580 and R Bork, Allgemeiner Teil des Bürgerlichen Gesetzbuchs (Mohr Siebeck, Tübingen, 2001) 274.

117 H Köhler (n 116) 464.

118 PY Gautier (n 113) 905.

119 ibid.

120 North Sea Continental Shelf Cases (n 111) diss. op. Judge Tanaka, 176; for a discussion on opinio iuris see with further references R Kolb, ‘Selected Problems in the Theory of Customary International Law’ (2003) 50 NILR 119, 123.

121 North Sea Continental Shelf Cases (n 111) para 77.

122 M Akehurst (n 99) 31; I Brownlie (n 110) 8; MN Shaw (n 108) 80; for further references S Yee, ‘The News that Opinio Juris ‘Is Not a Necessary Element of Customary [International] Law’ Is Greatly Exaggerated' (2000) 43 GYIL 227.

123 North Sea Continental Shelf Cases (n 111) para 77.

124 MH Mendelson (n 99) 290.

125 H Lauterpacht, ‘Sovereignty over Submarine Areas’ (1950) 27 BYIL 376, 395–396.

126 H Lauterpacht, The Development of International Law by the International Court (Stevens, London, 1958) 380; this is widely supported today, see eg G Dahm/J Delbrück/R Wolfrum, Völkerrecht (2nd edn, de Gruyter, Berlin, 1989) 60; PM Dupuy, Droit international public (8th edn, Dalloz, Paris, 2006) 338; P Malanczuk, Akehurst's Modern Introduction to International Law (7th edn, Routledge, London, 1997) 44; V Lowe (n 16) 40, 51; as well as Gulf of Maine Case (n 104) para 111.

127 Cf Y Dinstein (n 92) 276.

128 Military and Paramilitary Activities in and Against Nicaragua (n 20) para 186.

129 ibid para 207 et seq.

130 Fisheries Jurisdiction Case (United Kingdom of Great Britain and Northern Ireland v Iceland) (Judgment, Merits) (1974) [1974] ICJ Rep 3, and Fisheries Jurisdiction Case (Federal Republic of Germany v Iceland) (Judgment, Merits) (1974) [1974] ICJ Rep 175.

131 G Scelle, Précis de droit des gens – Principes et systématique, Tome I: Introduction – Le milieu intersocial (Recueil Sirey, Paris, 1932) 43; for authors exploring this idea see W Schiffer, The Legal Community of Mankind (Columbia UP, New York 1954) 264; MS McDougal (n 99) 357; A Verdross/B Simma, Universelles Völkerrecht (3rd edn, Duncker & Humblot, Berlin, 1984) MN. 46; A Cassese, ‘Remarks on Scelle's theory of ‘Role Splitting’ (dédoublement fonctionnel) in International Law' 1 (1990) EJIL 210; A Fischer-Lescano, Globalverfassung. Die Geltungsbegründung der Menschenrechte (Velbrück, Weilerswirst, 2005) 102, 160; for a historical account see M Koskenniemi, The Gentler Civilizer of Nations. The Rise and Fall of International Law 18701960 (CUP, Cambridge, 2002) 333–338.

132 G Scelle, ‘Le phénomène juridique du dédoublement fonctionnel’, in W Schätzel/HJ Schlochauer (eds), Rechtsfragen der internationalen Organisation. Festschrift für Hans Wehberg (Klostermann, Frankfurt/M. 1956) 324, 334–335.

133 B Fassbender, ‘The United Nations Charter As Constitution of the International Community’ (1997) 36 Col J Trans L 529, 567–568; and already H Wiebringhaus, Das Gesetz der funktionellen Verdoppelung: Beitrag zu einer universalistischen Theorie des Internationalprivat- und Völkerrechts (2nd edn, West-Ost-Verlag, Saarbrücken, 1955) 30–31.

134 Other examples for which the theory of dédoublement fonctionnel is still valid are given by A Cassese (n 131) 227: eg the possibility of countermeasures by not directly affected States or the increasing role played by national courts in the enforcement of international law, for an activist view on the latter question see A Fischer-Lescano (n 131) 102, 160.

135 MG Kohen, ‘US Use of Force After the Cold War’, in M Byers/G Nolte (eds), United States Hegemony and the Foundation of International Law (CUP, Cambridge, 2003) 197, 224.

136 O Corten, ‘The Controversies Over the Customary Prohibition on the Use of Force: A Methodological Debate’ (2005) 16 EJIL 803, 818.

137 Opinion of the Venice Commission (n 36) para 54.

138 See above notes 7 & 8.

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