Abstract The primary mandate of international adjudicators (such as Judges of the International Court of Justice and members of investor-State arbitral tribunals) is to settle the legal dispute presented to them in a given case. They have scope to decide scientific questions only in the course of settling those disputes. Many cases involving scientific issues do not call for findings of scientific facts by adjudicators. In those cases that do call for findings of scientific facts, however, the methodology of judicial assessment is not peculiar to scientific facts. Regardless of whether the facts at issue are scientific in nature, adjudicators rarely base their conclusions on direct evidence, relying instead on second-order indicators. These second-order indicators are well-suited to the evaluation of evidence adduced through party-appointed experts, but are of more limited use when a court or tribunal appoints its own expert. 1. INTRODUCTION Experts participate in international adjudication1 in a variety of ways, most commonly as party-appointed experts and, less frequently, as court-appointed experts.2 Although experts speak to many different subjects, these remarks focus on evidence adduced through the involvement of experts in the natural sciences, which I shall call ‘expert scientific evidence’. I wish to explore this question: How should adjudicators approach the assessment of expert scientific evidence? The scholarly writings of one of the organizers of this symposium, Professor Makane Mbengue, suggest a two-part answer to this question. First, Professor Mbengue calls for more robust scientific fact-finding by international courts and tribunals (ICTs), asserting that: international adjudication [c]ould constitute a new promised land for scientific fact-finding…3 Second, Professor Mbengue urges greater use of court-appointed scientific experts: It is indisputable — not to say evident — that international courts and tribunals would benefit by resorting more systematically to the ‘assistance of experts’ when confronted with issues of scientific fact-finding.4 Professor Mbengue and a colleague criticize the ICJ in particular for skirting difficult questions of scientific evidence.5 Their dissatisfaction echoes the more general observation that the ICJ often avoids resolving difficult questions of fact.6 I certainly understand why some observers are disappointed when the decision of the ICJ or another ICT does not resolve a scientific controversy. And I accept, to a degree, both of Professor Mbengue’s propositions: some cases before ICTs do call for scientific fact-finding and there are circumstances in which court-appointed experts can assist adjudicators in fact-finding. However, taking into account the context in which ICTs are confronted with expert scientific evidence (which I depict as concentric rings in the figure below), I conclude that increased scientific fact-finding by ICTs should not be an objective in its own right. I also suggest some caution regarding court-appointed scientific experts. I begin by positing (2.A.) that the primary mandate of adjudicators is to settle legal disputes, and then observe (2.B.) that many cases involving disputed scientific assertions do not call for a finding on scientific facts. Thereafter, I turn to the methodology of fact-finding that ICTs use, pointing out (2.C.a) that, in cases having nothing to do with science, adjudicators often base evidentiary conclusions on second-order indicators. They use similar second-order indicators to evaluate scientific evidence presented by party-appointed experts (2.C.ii), but those indicators do not translate well to the evaluation of evidence presented by court-appointed experts (2.C.iii). 2. THE CONTEXT FOR CONSIDERATION OF EXPERT SCIENTIFIC EVIDENCE A. The Mandate of Adjudicators When we evaluate the way in which ICTs assimilate expert scientific evidence, we must bear in mind the mandate of each ICT. To this end, drawing on the work of Yuval Shany, we can seek to identify the goals for which each form of international dispute settlement was established.7 I offer summary observations about the goals of the ICJ contentious case jurisdiction8 and investor-State arbitration. As to the ICJ’s contentious case jurisdiction, it appears that the primary goal of the drafters of the United Nations Charter and the Statute of the International Court of Justice was the settlement of legal disputes between States.9 The history of the Convention on the Settlement of Investment Disputes between States and Nationals of Other States (the ICSID Convention) reveals a similar goal for investor-State arbitration—to provide a forum for the settlement of disputes between host States and investors.10 Bearing in mind that the ICJ is accountable not only to disputing States but also the entire membership of the United Nations and that its proceedings and its decisions are available to the public, we can identify two additional goals for the Court—that its decisions would develop international law and would influence the behaviour of States not parties to a particular case.11 However, the ICJ has no mandate to pursue these two goals other than in the course of deciding contentious cases and rendering advisory opinions. It is unlikely that the drafters of the ICSID Convention had in mind the goals of law-development and of influencing the conduct of non-parties when they set out a mechanism for investor-State arbitration, which has traditionally functioned with a presumption that arbitral awards will remain confidential.12 The emergence of investment jurisprudence is one of the reasons for more recent calls for greater transparency. Did the mandate providers establish fact-finding as a goal of ICJ contentious case jurisdiction or of investor-State arbitration? I doubt it. Of course, both the ICJ and investor-State arbitral tribunals find facts, but they do so in pursuit of the primary goal for which they were established—the settlement of disputes. I agree with one of my former colleagues that ‘[t]he task of the Court … is to decide disputes of fact which have to be resolved in determining whether a party to the proceeding has breached its legal obligations.’13 Accordingly, adjudicators have a mandate to engage in scientific fact-finding when settlement of the legal dispute between the parties calls for the resolution of scientific facts. B. Framing the Question Presented to Adjudicators in a Case Some cases call for a judicial decision regarding disputed scientific evidence. For example, an allegation that one State has caused significant transboundary harm to another State requires adjudicators to weigh evidence on such issues as the extent of environmental harm and causation.14 In many cases involving scientific facts, however, the legal dispute to be decided by the adjudicators does not require resolution of the underlying scientific uncertainty. Suppose, for example, that an investor initiates arbitration, claiming that there was no scientific basis for the respondent State’s ban on use of a chemical and that the ban violates the respondent State’s fair and equitable treatment obligation. The respondent State disagrees, asserting that the chemical was banned because it poses an environmental or health risk. Allegations of this sort often appear in investor-State arbitration, as illustrated by Methanex Corporation v United States15 and Chemtura v Canada.16 In Chemtura v Canada, the investor, which produced a pesticide used to treat seeds, alleged that Canada’s phase-out of the use of the pesticide violated the fair and equitable treatment and expropriation obligations of the North American Free Trade Agreement (NAFTA). The Tribunal made clear that its task was not to determine whether certain uses of this pesticide were dangerous.17 It considered instead whether Canada’s process of reviewing the use of the pesticide was undertaken pursuant to the mandate of the reviewing regulatory agency and in implementation of Canada’s obligations under environmental treaties or was instead driven by trade concerns (as the investor claimed).18 To this end, the Tribunal examined the manner in which Canada had launched and conducted its review of the pesticide, relying on testimony of Canadian officials involved the review. It found that the evidence did not show bad faith or disingenuous conduct on the part of Canada and that the review of the pesticide was undertaken pursuant to the mandate of the reviewing agency and as a result of Canada’s international obligations. It concluded that Canada had met its obligations under NAFTA.19 In cases like Chemtura, courts and tribunals decide the case without passing judgment on the underlying scientific questions, eg, the risk posed by a particular substance. Such decisions may disappoint observers who wish for a clearer conclusion regarding the underlying scientific facts, but the adjudicators are addressing the question presented by the dispute before them, in a manner that is faithful to their mandate. C. Methodology of fact-finding (i) In General Professors d’Aspremont and Mbengue have stated that ‘scientific fact-finding enunciates “probabilities” while traditional fact-finding methods validate “veracities”’.20 I believe that this distinction is overstated. The assessment of evidence often takes place under conditions of uncertainty, as is reflected in one widely used formulation of a standard of proof—‘the balance of probabilities’.21 An allegation that a respondent State bears international responsibility for alleged violations of human rights law, for example, can rarely be evaluated by direct assessment of concrete evidence. Instead, such cases require adjudicators to weigh probabilities in order to form conclusions on difficult questions such as an alleged perpetrator’s intent or purpose and the extent of the State’s control over the conduct of that person. The difficulty of reaching conclusions about disputed questions of fact leads adjudicators to assess evidence using techniques that have been called ‘second-order indicators’.22 For example, adjudicators frequently identify those facts on which the parties agree, and proceed on the basis of party agreement.23 When a party admits facts that are unfavourable to it, adjudicators treat those facts as established without further inquiry.24 Adjudicators give particular weight to statements that are adverse to the party with which the person making the statement is associated.25 When adjudicators examine the testimony of a witness, they employ a variety of second-order indicators. For example, the ICJ: considers whether a witness is disinterested, giving greater weight to testimony of someone who has nothing to gain or to lose, as well as to statements against interest (Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, Judgment, I.C.J. Reports 1986, pp. 42–43, para. 69). The Court distinguishes between facts within the witness’s personal knowledge, on the one hand, and speculation or repetition of information learned from others (sometimes called ‘hearsay’) on the other hand (ibid., p. 42, para. 68). The Court gives particular weight to statements that are contemporaneous with the events at issue (Territorial and Maritime Dispute between Nicaragua and Honduras in the Caribbean Sea (Nicaragua v. Honduras), Judgment, I.C.J. Reports 2007 (II), p. 731, para. 244).26 ICTs draw inferences to fill gaps in direct evidence.27 Negative inferences have particular significance when a respondent State can be expected to possess information that it fails to produce. For example, when the respondent State failed to produce any evidence to support its claim that it had informed an individual of the reasons for his arrest and expulsion, the ICJ drew negative inferences.28 When investor-State tribunals apply the International Bar Association Rules on the Taking of Evidence in International Arbitration (2010) (IBA Rules), a party’s failure to produce documents can lead to an inference that is adverse to that party.29 Bearing in mind the overall importance of second-order indicators in the resolution of difficult questions of evidence, I turn to the methodology that applies to scientific evidence adduced through experts. (ii) Scientific Evidence Presented by Party-Appointed Experts When adjudicators evaluate scientific evidence presented by party-appointed experts, they make extensive use of the same kinds of second-order indicators that they use to evaluate other kinds of evidence. I review some of the second-order indicators used in relation to party-appointed experts and then turn to the evaluation of evidence presented by court-appointed experts. Adjudicators apply second-order indicators to evaluate the reliability and credibility of a party-appointed expert, much as they do with fact witnesses. Both the expert and the appointing party can be expected to establish the expert’s independence, qualifications and areas of expertise,30 and opposing counsel inevitably look for opportunities to erode the adjudicators’ confidence in the other party’s expert. Other second-order indicators contribute to the evaluation of the evidence adduced by party-appointed experts. Adjudicators seek to narrow the factual dispute by identifying points on which party-appointed experts agree.31 The importance of agreement between experts is illustrated by the IBA Rules, widely applied in investor-State arbitration, pursuant to which a tribunal may require the parties’ experts to record their points of agreement and disagreement.32 Adjudicators also give particular weight to opinions of an expert that are adverse to the party that appointed the expert.33 The unexplained failure to present scientific evidence can lead to an adverse inference. When the ICJ rejected Nicaragua’s claim that Costa Rica’s construction of a road had caused substantial environmental harm to Nicaragua, the Court pointed out that Nicaragua had not produced direct evidence in support of certain assertions, relying only on modelling and estimates by its experts.34 Courts also take into account a party’s failure to refute the evidence of the other party’s expert.35 An important second-order indicator of the reliability of expert scientific evidence is the methodology used by an expert. Under the IBA Rules,36 the report of a party-appointed expert must include ‘a description of the methods, evidence and information used’ in reaching conclusions. ‘One of the key qualities required for any technical assertion to be deemed compatible with scientific methodology is that it be independently verifiable or susceptible to peer review’.37 Each party typically seeks to undermine the scientific conclusions advanced by the other party by pointing to what it regards as methodological errors of the other party’s experts, criticizing, for example, ‘the care with which [the] analysis was conducted, its completeness, the accuracy of the data used, and the clarity and coherence of the conclusions drawn from such data’.38 Second-order indicators such as those noted here often determine the conclusions of an ICT on disputed scientific facts. In addition, when adjudicators state their conclusions on difficult questions of fact, whether scientific or not, the burden of proof plays an important role. Instead of stating directly that a particular fact did or did not occur, adjudicators typically conclude that a party has ‘failed to provide sufficient evidence’ of an alleged fact39 or has not proven those facts.40 (iii) Scientific Evidence Presented by Court-Appointed Experts The second-order indicators that are used in relation to party-appointed experts do not operate in the same manner when adjudicators assess evidence presented by a court-appointed expert. As with party-appointed experts, the adjudicators can consider the indicators related to the independence and expertise of the expert. However, they can be expected to consider these indicators most carefully prior to appointing the expert, taking into account party views. Moreover, although adjudicators are not bound by the conclusions of the experts they appoint, they are likely to invoke second-order indicators only to lend credence to the conclusions of an expert appointed by them. Their tendency will be to avoid the conclusion that an expert appointed by them made methodological errors. The parties might also refrain from challenging the conclusions of an expert chosen by an ICT, for fear that this would be interpreted as a challenge to the authority of the ICT itself. Under these circumstances, all participants in the proceedings may feel constrained to accept the court-appointed expert’s findings as definitive, which could determine the outcome in the case. 3. CONCLUSION Taken as a whole, the mandate of international institutions does not come close to matching the range of powers and functions assigned to the organs of States. These limitations can lead to disappointment about the inability of international law and institutions to solve pressing problems. The limited mandate of international courts and tribunals is one reason (although not the only reason) why their decisions are seen at times as missed opportunities to fill gaps in international governance, whether through an authoritative decision on disputed facts or through the development of international law.41 However, these opportunities are only available to an international court or tribunal in the course of settling the dispute presented to it. That is why, when an ICT is confronted with a case raising scientific controversies, it must consider with particular care the framing of the legal dispute presented to it and the extent to which that dispute calls for decisions on scientific evidence. Adjudicators also need a clear appreciation of the dispute that is presented in a case in order to decide whether to appoint an expert. If the dispute calls for a decision on scientific evidence and there are reasons to doubt the adequacy of evidence presented by the parties (including through their experts), appointment of an expert may be warranted. The dispute, as framed by the adjudicators, informs both the necessary areas of expertise and the terms of reference to be given to the expert. Prior to appointing an expert, adjudicators must follow procedures that allow for party input, thus stemming later criticism of an expert’s independence or expertise or of the terms of reference. They must also consider whether they are prepared to temper their reliance on second-order indicators such as the expert’s methodology, placing themselves instead in a situation in which they ‘cannot fail to give great weight’ to the opinion of the expert appointed by them.42 Footnotes 1 For convenience, I use the terms ‘adjudication’ and ‘court’ to refer not only to international courts, but also to international arbitration and other mechanisms for the binding settlement of a dispute to which at least one party is a State. I use the term ‘adjudicator’ to refer to the international decision-makers (eg, judges, arbitrators). 2 In the International Court of Justice (ICJ), Court appointment of an expert is to take place ‘after hearing the parties’, who are to be given an opportunity to comment on expert reports (Rules of Court, art 67). However, the Court has at times consulted experts without engaging the parties, a practice that has raised justifiable concerns. The Court’s Statute (art 30, para 2) also permits the Court to engage ‘assessors’ who may participate (without a vote) in the Court’s deliberations, although the Court has never done so. See generally Giorgio Gaja, ‘Assessing Expert Evidence in the ICJ’, (2016) 15 The Law and Practice of International Courts and Tribunals 409. 3 Makane Moïse Mbengue, ‘International Courts and Tribunals as Fact-Finders: The Case of Scientific Fact-Finding in International Adjudication’ (2011) 34 Loyola LA Int’l & Comp L Rev 53, 67. 4 ibid 53, 75. 5 Jean d’Aspremont and Makane Moïse Mbengue, ‘Strategies of Engagement with Scientific Fact-Finding’ (2014) 5 JIDS 240, 252–6. The authors do not mince words, stating that the ICJ ‘has constantly been stifling scientific issues by hiding behind legal reasoning and using legal rationality to shield itself from scientific controversies’. ibid, 252. 6 See eg Thomas M Franck, ‘Fact-Finding in the ICJ’ in Richard B Lillich (ed), Fact-Finding Before International Tribunals (Transnational Publishers 1992) 21. 7 See Yuval Shany, Assessing the Effectiveness of International Courts (OUP 2014). Professor Shany has suggested that we evaluate the effectiveness of various international courts and tribunals with reference to the goals of the ‘mandate providers’ who established a particular form of international adjudication. He recognizes that the effectiveness of an ICT can also be evaluated with reference to goals other than those of the mandate providers (ibid, 6, 23–25). 8 I focus here on contentious cases before the ICJ, although, of course, the Court has the additional mandate to render advisory opinions. 9 See Shany (n 7) 166; Malcom N Shaw, Rosenne’s Law and Practice of the International Court: 1920–2015 (5th edn, Brill Nijhoff 2016), vol I, 165. 10 See Aron Broches, ‘The Convention on the Settlement of Investment Disputes Between States and Nationals of Other States’ (1972) 136 Recueil des cours 337, 342–50. 11 Joan E Donoghue, ‘The Effectiveness of the International Court of Justice’ (2014) ASIL Proceedings 114, 116. See also Shany (n 7) 166–8. 12 ICSID Convention art 48(5). 13 Pulp Mills on the River Uruguay (Argentina v Uruguay) (Merits)  ICJ Rep 14, Separate Opinion of Judge Keith 121, . 14 See eg Pulp Mills, ibid; Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) and Construction of a Road in Costa Rica along the San Juan River (Nicaragua v Costa Rica)  (II) ICJ Rep 665. 15 Methanex Corporation v United States of America (Final Award on Jurisdiction and Merits, 3 August 2005, ad hoc UNCITRAL Tribunal under NAFTA Ch 11), available at www.italaw.com. 16 Chemtura Corporation v Government of Canada (Award, 2 August 2010, ad hoc UNCITRAL Tribunal under NAFTA Ch 11) <www.italaw.com> accessed 13 April 2018. 17 ibid, . 18 ibid, . 19 ibid, –, . 20 d’Aspremont and Mbengue (n 5) 246. 21 Consistent with traditions in civil law jurisdictions, the ICJ has not explicitly adopted a generallyapplicable standard of proof. However, the Court’s reasoning suggests that, in general, it reaches conclusions based on the balance of probabilities. See Pulp Mills (n 14), Separate Opinion of Judge Greenwood 221, –. 22 See Oren Perez, ‘Judicial Strategies for Reviewing Conflicting Expert Evidence: Biases, Heuristics, and Higher-Order Evidence’ (2016) 64 Am J Comp L 75, 78, distinguishing between the direct assessment of evidence and the use of second-order indicators and Evan Bell, ‘Judicial Assessment of Expert Evidence’ (2010) 2 Judicial Studies Institute Journal 55 (describing techniques used by British judges to evaluate expert evidence). 23 Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Croatia v Serbia) (Merits)  (I) ICJ Rep 1, , –. 24 See eg Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits)  ICJ Rep 13, ; Genocide (Croatia v Serbia) (n 23) , , and . 25 Nicaragua v United States of America, ibid . 26 Genocide (Croatia v Serbia) (n 23), Declaration of Judge Donoghue 390, ; see also the Judgment –. 27 Corfu Channel Case (UK v Albania) (Merits)  ICJ Rep 1, 18. 28 Ahmadou Sadio Diallo (Republic of Guinea v Democratic Republic of the Congo),  ICJ Rep 638,  and . 29 IBA Rules, art 9(5). 30 ibid, art 5(2). 31 See eg Whaling in the Antarctic (Australia v Japan: New Zealand Intervening)  ICJ Rep 225, , , ; Certain Activities and Construction of a Road (n 14)  and . 32 IBA Rules (n 29), art 5(4). 33 Australia v Japan (n 31) , , . 34 Certain Activities and Construction of a Road (n 14)  and . 35 Australia v Japan (n 31) . 36 IBA Rules (n 29), art 5(2)(e). 37 Nigel Blackaby and Alex Wilbraham, ‘Practical Issues Relating to the Use of Expert Evidence in Investment Treaty Arbitration’ (2016) 31 ICSID Review 655, 660. 38 Pulp Mills (n 13) . 39 Genocide (Croatia v Serbia) (n 23) . 40 Certain Activities and Construction of a Road (n 14) , , . 41 See eg Diane Desierto, ‘Evidence but not Empiricism? Environmental Impact Assessments at the International Court of Justice in Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua) and Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v. Costa Rica)’ (EJIL: Talk! 26 February 2016) <https://www.ejiltalk.org/evidence-but-not-empiricism-environmental-impact-assessments-at-the-international-court-of-justice-in-certain-activities-carried-out-by-nicaragua-in-the-border-area-costa-rica-v-nicaragua-and-con/> accessed 7 November 2017; Marko Milanovic, ‘On the Entirely Predictable Outcome of Croatia v. Serbia’ (EJIL: Talk! 6 February 2015) <https://www.ejiltalk.org/on-the-entirely-predictable-outcome-of-croatia-v-serbia/> accessed 7 November 2017. 42 Corfu Channel (n 27) 21. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: email@example.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
Journal of International Dispute Settlement – Oxford University Press
Published: Apr 20, 2018
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