1 Referred to as ‘external judicial decisions’ or ‘external precedent’.

2 A. Cassese, ‘The Influence of the European Court of Human Rights on International Criminal Tribunals – Some Methodological Remarks’, in M. Bergsmo (ed.) Human Rights and Criminal Justice For the Downtrodden: Essays in Honour of Asbjorn Eide (2003), 26.

3 The elements of this appraisal are discussed below.

4 Only judgments delivered by 18 May 2012 have been included (this date was chosen to be inclusive of the SCSL's Taylor Trial Judgment). The article provides only a limited number of representative examples from this analysis. A full list of judgments is available on record with the author.

5 The paper does not cover external judicial decisions used in relation to rules of procedure and evidence and sentencing because of the tribunal-specific and sui generis nature of these rules. See Stahn, C. and van den Herik, L., ‘“Fragmentation”, Diversification and “3D” Legal Pluralism: International Criminal Law as the Jack-in-the-Box’, in van den Herik, L. and Stahn, C. (eds.), The Diversification and Fragmentation of International Criminal Law (2012), 78–79Google Scholar. It is acknowledged, however, that in some cases the line between substance and procedure may be difficult to draw and ‘[w]hile textbooks commonly contain separate sections dealing with substantive and procedural law, respectively, the question of where the dividing line lies, and how they are connected, is usually neglected’: see Nollkaemper, A., ‘International Adjudication of Global Public Goods: The Intersection of Substance and Procedure’, (2012) 23 EJIL 769, at 771CrossRefGoogle Scholar.

6 Romano, C. P. R., ‘Deciphering the Grammar of the International Jurisprudential Dialogue’, (2009) 41 J Int’L L & Pol 755, at 758Google Scholar. See also Slaughter, A. M., ‘A Global Community of Courts’, (2003) 44 Harv Int’l L J 191Google Scholar, at 194.

7 For instance, Anderson maintains that ‘[j]udges have a duty to administer justice in the particular case, while keeping in mind the coherence of the legal system as a whole’: see Anderson, D., ‘The “Disordered Medley” of International Tribunals And the Coherence of International Law’, in Kaikobad, K. H. and Bohlander, M. (eds.), International Law and Power: Perspectives on Legal Order and Justice: Essays in Honour of Colin Warbrick (2009), 397Google Scholar.

8 The Report by the International Law Commission (‘ILC’) on the Fragmentation of International Law examines the conflict between the Nicaragua and Tadić decisions under the heading ‘Fragmentation through Conflicting Interpretations of General Law’ and states, inter alia, ‘[t]he contrast between Nicaragua and Tadic is an example of a normative conflict between an earlier and a later interpretation of a rule of general international law’: see Report of the Study Group of the International Law Commission, Fragmentation of International Law: Difficulties Arising from the Diversification and Expansion of International Law (finalized by Martti Koskenniemi), UNGA 58th session, Doc. No. A/CN.4/L.682 (13 April 2006), at paras. 49–50. See also Acquaviva, G., ‘Aiding and Abetting International Crimes and the Value of Judicial Consistency: Reflections Prompted by the Perisic, Taylor and Sainovic verdicts’, (2014) 3 Questions of International Law 3Google Scholar, at 4.

9 See Fitzmaurice, G. G., ‘Some Problems Regarding the Formal Sources of International Law’, in Koskenniemi, M., Sources of International Law (2000), 153 at 171Google Scholar.

10 See Nollkaemper, A., ‘Decisions of National Courts as Sources of International Law: An Analysis of the Practice of the ICTY’, in Boas, G. and Schabas, W. (eds.), International Criminal Law Developments in the Case Law of the ICTY (2003), 277Google Scholar.

11 Prosecutor v. Zoran Kupreškić, Mirjan Kupreškić, Vlatko Kupreškić, Drago Josipović, Dragan Papić, Vladimir Šantić, also known as ‘Vlado’, Judgment, Case No. IT-95–16-T, 14 January 2000, at para. 542. Emphasis added. Significantly, however, this paper diverges from the Kupreškić et al. holding in that it requires such appraisals to be made express in the judgment.

12 Oxford English Dictionary Online, ‘Definition of appraise’, <http://www.oed.com/view/Entry/9774?redirectedFrom=appraise#eid> (accessed 5 January 2015).

13 An example of such a local idiosyncrasy, taken from a different branch of international law, relates to the ICJ's Nicaragua case and the US reservation to the jurisdiction of the Court. As Bianchi observes, ‘[t]he Connelly reservation, attached by the US to the unilateral declaration of acceptance of the Court's jurisdiction, prevented the Court from applying the [UN] Charter to the case at hand. Therefore, in order to decide the case on the merit, the Court was compelled to find rules of customary international law applicable to the conduct of the United States, regardless of the UN Charter provisions’: see A. Bianchi, ‘The International Regulation of the Use of Force: The Politics of the Interpretive Method’ in L. van den Herik and N. Schrijver (eds.), Counter-Terrorism Strategies In a Fragmented International Legal Order: Meeting the Challenges (2013), 296. In this case, the US reservation may be characterized as a local idiosyncrasy which influenced the applicable law in Nicaragua. Indeed, Bianchi postulates that ‘the ICJ's findings might have been prompted by the need to circumvent the difficulty posed by the Connelly reservation to the jurisdiction of the Court’: see ibid.

14 Cassese, A.et al., International Criminal Law: Cases & Commentary (2011), 13Google Scholar.

15 Cassese, A., International Criminal Law (2008), 8Google Scholar. See also Safferling, C. J. M. and Büngener, L., International Criminal Procedure (2012), 25CrossRefGoogle Scholar.

16 See Cassese et al., supra note 14, at 1.

17 Prosecutor v. Milorad Krnojelac, Judgment, Case No. IT-97–25-T, 15 March 2002, at para. 181.

18 Cassese notes that when the ad hoc tribunals had reached a stage when a copious case law had been developed, in some cases, it no longer remained necessary for the tribunals to discuss the applicable law at great length and they confined themselves to citing previous case law without necessarily undertaking a detailed analysis. See A. Cassese, ‘Black Letter Lawyering v. Constructive Interpretation: The Vasiljević Case’, (2004) 2 JICL 265, at 265.

19 Elsewhere, this author has examined the approaches of judges to external precedent through the direct and indirect lenses. That analysis focused on whether judges relied on the legal findings or conclusions of particular external judicial decisions directly (the direct approach) or whether they borrowed from such decisions the reviews of state practice and opinio juris in the context of custom or, in the context of general principles, the surveys of national jurisdictions (the indirect approach). That analysis thus has a different focus from the present enterprise. See Zammit Borda, A., ‘The Direct and Indirect Approaches to Precedent in International Criminal Courts and Tribunals’, (2013) 14 MJIL 608–42Google Scholar.

20 For a notable exception, see Cassese, supra note 2, at 19.

21 Ibid., at 21.

22 Ibid., at 21–22.

23 See Zammit Borda, supra note 19, at 612.

24 For instance, in his celebrated dissent in Erdemović, Judge Li appeared to depart from the traditional view of judicial decisions as subsidiary means under Art. 38(1)(d) of the ICJ Statute. He ‘took the position that legal norms might be inferred from case law, including national case law, and that the criteria for doing so were distinct from the identification of rules of customary law or general principles of law’: see Nollkaemper, supra note 10, at 290. See also Zammit Borda, A., ‘The Use of Precedent as Subsidiary Means and Sources of International Criminal Law’, (2013) 18 Tilburg Law Review 65, at 75CrossRefGoogle Scholar.

25 For a discussion of judicial decisions under Art. 38(1)(d) of the ICJ Statute, see Borda, A. Zammit, ‘A Formal Approach to Article 38(1)(d) of the ICJ Statute from the Perspective of the International Criminal Courts and Tribunals’, (2013) 24 EJIL 649CrossRefGoogle Scholar, at 649. It is noted that ‘[j]udicial decisions used as evidences of customary international law are more intimately connected with the law-creating processes, and their consideration under Article 38(1)(d) risks muddying the distinction between law-creating processes and law-determining agencies. As such, they are more appropriately considered under Art. 38(1)(b), rather than Art. 38(1)(d). The same reasoning applies to all judicial decisions used as material sources of rules of international law, such as judicial decisions used in identifying (or negating) general principles of law’, ibid., at 657.

26 Kupreškić et al. Trial Judgment, supra note 11, at para. 540.

27 Prosecutor v. Édouard Karemera, Athieu Ngirumpatse, Joseph Nzirorera, Decision on Interlocutory Appeal Regarding Witness Proofing, Case No. ICTR-98–44-AR73.8, 11 May 2007, at para. 7.

28 Kaing Guek Eav alias ‘Duch’, Appeal Judgment, Case No. 001/18–07–2007-ECCC/SC, 3 February 2012, at para. 97.

29 The distinction between binding force and persuasive value of external precedent, particularly when viewed in binary terms, has been challenged. Jacob, for instance, makes the point that ‘a crude binary understanding of a case's normativity (‘binding or not’) belies the complexity of the reasoning processes accompanying the practical application of precedents’: see Jacob, M., ‘Precedents: Lawmaking Through International Adjudication’, (2011) 12 German Law Journal 1005, at 1015–16Google Scholar.

30 Prosecutor v. Issa Hassan Sesay, Morris Kallon, Augustine Gbao, Judgment, Case No. SCSL-04–15-T, 2 March 2009, at para. 295.

31 See Acquaviva, supra note 8, at 13.

32 Prosecutor v. Thomas Lubanga Dyilo, Judgment pursuant to Article 74 of the Statute, Case No. ICC-01/04–01/06, 14 March 2012, at para. 603.

33 Nerlich considers that the basis for using external precedent when interpreting the Rome Statute and its subsidiary instruments may be found ‘in a broader conception of the context in which these instruments have to be interpreted, and in the purpose underlying Article 31(3)(c) of the Vienna Convention’: see Nerlich, V., ‘The Status of ICTY and ICTR Precedent in Proceedings Before the ICC’, in Stahn, C. and Sluiter, G., The Emerging Practice of the International Criminal Court (2009), 320Google Scholar.

34 See Acquaviva, supra note 8, at 8.

35 Dixon, R. and Khan, K. A. A., Archbold on International Criminal Courts: Practice, Procedure and Evidence (2009), 171 (para. 5–56)Google Scholar. Schabas considers that ‘the text of [Art. 21(s) of the Rome Statute] clearly applies only to case law of the Court, but surely cannot be taken as depriving the Court of the authority to consider principles and rules of law derived from the case law of other judicial bodies. There are too many examples of references to the case law of the ad hoc tribunals and human rights courts like the European Court of Human Rights for such an a contrario interpretation of Article 21(2) to be entertained’: see Schabas, W., The International Criminal Court: A Commentary on the Rome Statute (2010), 396CrossRefGoogle Scholar.

36 Nerlich however continues, ‘but it does exist and if used in full awareness of its weakness, it may well make for a better understanding of the provisions that the ICC has to apply’: see Nerlich, supra note 33, at 320.

37 Bohlander and Findlay, for instance, find that, in the ICTY decisions they analysed, common law sources had been used more frequently than civil law sources and they argue that more emphasis should be placed on the ‘legal-methodological integrity’ of the selection process: see M. Bohlander and M. J. Findlay, ‘The Use of Domestic Sources as a Basis for International Criminal Law Principles’, (2002) The Global Community Yearbook of International Law and Jurisprudence 2, at 7.

38 Ibid., at 12.

39 McCormick proceeds to characterize the universe of citable decisions an ‘uneven playing field’: see McCormick, P., ‘The Evolution of Co-ordinate Precedential Authority in Canada: Interprovincial Citations of Judicial Authority 1922–92’, (1994) 32 Osgoode Hall Law Journal 271, at 282Google Scholar.

40 McCormick, P., ‘Judicial Authority and the Provincial Courts of Appeal: A Statistical Investigation of Citation Practices’ (1993–1994) 22 Manitoba Law Journal 286, at 297–8Google Scholar.

41 The Trial of Otto Ohlendorf et al., in Trials of War Criminals before the Nürnberg Military Tribunals under Control Council Law No. 10, (U.S. Govt Printing Office, Washington D.C., 1950), vol. IV (‘the Einsatzgruppen case’).

42 Prosecutor v. Dragen Erdemović, Judgment, Case No. IT-96–22-A, 7 October 1997, at para. 27 (Separate And Dissenting Opinion Of Judge Cassese).

43 Ibid., at para. 53 (Joint Separate Opinion of Judge McDonald and Judge Vohrah).

44 Ibid., at para. 54 (Joint Separate Opinion of Judge McDonald and Judge Vohrah).

45 See Von Lewinski (called von Manstein), British Military Court at Hamburg (Germany), 19 December 1949, in 16 Annual Dig. and Reports of Public International Law Cases 509, 521 (1949), cited in Prosecutor v. Radislav Krstić, Judgment, Case No. IT-98–33-T, 2 August 2001, at para. 526.

46 Krstić Trial Judgment, ibid., at para. 526 (fn. 1178).

47 Ibid.

48 Ibid., at para. 577.

49 Federal Constitutional Court, 2 BvR 1290/99, 12 December 2000, para. (III)(4)(a)(aa).

50 Krstić Trial Judgment, supra note 45, at para. 580.

51 Prosecutor v. Vidoje Blagojević, Dragan Jokić, Judgment, Case No. IT-02–60-T, 17 January 2005, at para. 665.

52 Ibid., at para. 664.

53 Prosecutor v. Vidoje Blagojević, Dragan Jokić, Judgement, Case No. IT-02–60-A, 9 May 2007, at para. 123.

54 Hunt, D., ‘The International Criminal Court: High Hopes, ‘Creative Ambiguity’ and an Unfortunate Mistrust in International Judges’, (2004) 2 JICL 56, at 67Google Scholar.

55 Hunt observes that ‘[n]o such requirement of policy exists in current international criminal law’: see ibid., at 64–65.

56 Ibid., at 64.

57 Prosecutor v. Dragoljub Kunarac, Radomir Kovac and Zoran Vukovic, Judgment, Case No. IT-96–23–23/1-A, 12 June 2002, at para. 98 (fn. 114).

58 Duxbury, N., The Nature and Authority of Precedent (2008), 99CrossRefGoogle Scholar.

59 Hunt, supra note 54, at 60–61.

60 Art. 10 provides that ‘Nothing in this Part shall be interpreted as limiting or prejudicing in any way existing or developing rules of international law for purposes other than this Statute.’ Art. 21 (Applicable Law) refers to the various sources to which the Court may have recourse and refers, inter alia, to general principles of law and those principles and rules of law ‘as interpreted in its previous decisions’. See also Hunt, supra note 54, at 60–61 (fn. 22).

61 Art. 22(2) of the Rome Statute.

62 For instance, in case of ambiguity with respect to the definition of a crime, this should be interpreted in favour of the person being investigated, prosecuted or convicted (see Art. 22(2) of the Rome Statute).

63 Nerlich, supra note 33, at 317.

64 On the complex relationship between the Rome Statute and customary international law, Grover observes that ‘[o]n balance, it is submitted that states parties should be presumed to have intended that Articles 6, 7, and 8 [of the Rome Statute], to the extent possible and without violating the principle of legality, be interpreted in light of relevant and applicable law as it existed when the crime is alleged to have been committed . . . Further, Articles 10 and 22(3) [of the RS] contemplate custom evolving and Article 21(2) [RS] renders custom and treaty law authoritative interpretive aids. In interpreting Articles 6, 7, and 8 in light of relevant and applicable law which exists at the time the alleged crime was committed, Article 22 serves as a reminder that, where the Rome Statute cannot be reconciled with subsequent law, the definitions of crimes in Articles 6, 7, and 8 prevail’: see Grover, L., ‘A Call to Arms: Fundamental Dilemmas Confronting the Interpretation of Crimes in the Rome Statute of the International Criminal Court’, (2010) 21 EJIL 543CrossRefGoogle Scholar, at 581–2.

65 Cryer, R.et al., An Introduction to International Criminal Law and Procedure (2010), 12CrossRefGoogle Scholar. In Čelebići, the judges at the trial chamber noted that in any national legal system, legal notions are ‘utilised in a specific legal context and are attributed their own specific connotations by the jurisprudence of that system’: Prosecutor v. Zejnil Delalic, Zdravko Mucic also known as ‘Pavo’, Hazim Delic, Esad Landzo also known as ‘Zenga’, Judgment, Case No. IT-96–21-T, 16 November 1998, at para. 431.

66 Attorney General of Israel v. Adolf Eichmann 36 ILR 5, Jerusalem District Court (12 December 1961).

67 Prosecutor v. Jean-Paul Akayesu, Judgment, Case No. ICTR-96–4-T, 2 September 1998, at para. 503.

68 Ibid.

69 Schabas, W., ‘Judicial Activism and the Crime of Genocide’, in Darcy, S. and Powderly, J. (eds.), Judicial Creativity at the International Criminal Tribunals (2010), 64Google Scholar.

70 For instance, it has been pointed out that ‘to proscribe the murder of Jews as a crime against Jews carries the dangerous implication that it is not a crime against non Jews. [. . .T]o define a crime in terms of the religion or nationality of the victim, instead of the nature of the criminal act, is wholly out of keeping with the needs of the times and trend of modern law’: see T. Taylor, ‘Large Questions in the Eichmann Case’, New York Times Magazine, 22 January 1961. Kittrie notes that although ‘[t]he explanation has been offered, in partial answer to this argument, that in referring to “crimes against the Jewish people” the Israeli law was merely classifying the object of the crime, similar to the way a statute book may divide offenses according to whether they are “crimes against property” or “crimes against a person” . . . Yet the question remains whether such differentiation between the objects of international crimes serves a valid purpose and is at all necessary’. See N. K. Kittrie, ‘A Post Mortem of the Eichmann Case. The Lessons for International Law’, (1964) 55 Journal of Criminal Law, Criminology, and Police Science, at 24–25.

71 Fédération Nationale Des Déportés et Internés Résistants et Patriotes and Others v. Barbie, ‘Arrêt’, French Court of Cassation (Criminal Chamber), International Law Reports, vol. 78 (1985).

72 See the reference in Prosecutor v. Mile Mrksić, Miroslav Radić, Veselin Šljivančanin, Judgment, Case No. IT-95–13/1-T, 27 September 2007, at para. 450.

73 Prosecutor v. Dusko Tadić aka ‘Dule’, Judgment, Case No. IT-94–1-T, 7 May 1997, at para. 641.

74 Ibid., at para. 642.

75 Ibid.

76 Ibid., at para. 643.

77 Prosecutor v. Tihomir Blaškić, Judgment, Case No. IT-95–14-T, 3 March 2000, at para. 212.

78 Kupreškić et al. Trial Judgment, supra note 11, at para. 548.

79 Ibid.

80 See Sadat, L. N., ‘The Nuremberg Paradox’, (2010) 58 Am J Comp L 151, at 180CrossRefGoogle Scholar.

81 This interpretation was affirmed in a judgment of the Court of Cassation of 3 June 1988. Moreover, Sadat argues that the French Court of Cassation interpreted Art. 6(c) of the Nuremberg Charter (on crimes against humanity) in order to permit Barbie's trial in France, while at the same time limiting the Nuremberg Charter's application to any crimes outside the World War II context, thus potentially shielding democratic states from criminal liability. See ibid., at 181.

82 See, inter alia, Prosecutor v. Tihomir Blaškić, Judgment, Case No. IT-95–14-A, 9 July 2004, at para. 113; Prosecutor v. Dario Kordić and Mario Čerkez, Judgment, Case No. IT-95–14/2-A, 17 December 2004, at para. 97; and Prosecutor v. Stanislav Galić, Judgment, Case No. IT-98–29-A, 30 November 2006, at para. 144.

83 Transcript of Prosecutor v. Mile Mrksić, Miroslav Radić, Veselin Šljivančanin, Review of the Indictment Pursuant to Rule 61 of the Rules of Procedure and Evidence (Mrksić (Vukovar) Rule 61 Decision), Case No. IT-95–13-I, 3 April 1996.

84 Mrksić et al. Trial Judgment, supra note 72, at para. 481.

85 Ibid., at paras. 479–81.

86 Ibid., at paras. 483–4.

87 Prosecutor v. Paul Bisengimana, Judgment, Case No. ICTR-00–60-T, 13 April 2006, at para. 49.

88 Ibid., at para. 9.

89 Prosecutor v. Anto Furundžija, Judgment, Case No. IT-95–17/1-T, 10 December 1998, at para. 160.

90 Ibid., at paras. 159–62.

91 Ibid.

92 Prosecutor v. Dragoljub Kunarac, Radomir Kovac, and Zoran Vukovic, Judgment, Case No. IT-96–23-T& IT-96–23/1-T, 22 February 2001, at paras. 470–71. Emphasis added.

93 Krstić Trial Judgment, supra note 45, at para. 601.

94 The Prosecutor v. Athanase Seromba, Judgment, Case No. ICTR-2001–66-I, 13 December 2006, at para. 302.

95 It should be noted that, in this case, the trial chamber also referred to the internal decision of The Prosecutor v. Clément Kayishema and Obed Ruzindana, Judgment, Case No. ICTR-95–1-A, 1 June 2001, at para. 187.

96 The Prosecutor v. Athanase Seromba, Judgment, Case No. ICTR-2001–66-A, 12 March 2008, at para. 161.

97 Kaing Guek Eav alias Duch, Judgment, Case No. 001/18–07–2007/ECCC/TC, 26 July 2010, at para. 361.

98 Kaing Guek Eav alias ‘Duch’, Appeal Judgment, Case No. 001/18–07–2007-ECCC/SC, ECCC Supreme Court Chamber, 3 February 2012, at para. 178.

99 Ibid., at para. 180.

100 Cassese, supra note 2, at 22.

101 See Kunarac et al. Trial Judgment, supra note 92, at paras. 470–71.