Simon's Megalomaniacal Legal Resources

Public International Law - Proving International Law

. International Air Transport Association v. Canada (Transportation Agency)

In International Air Transport Association v. Canada (Transportation Agency) (SCC, 2024) the Supreme Court of Canada dismissed an appeal, here involving "the vires of the Air Passenger Protection Regulations, SOR/2019-150 (“Regulations”) [SS: under the 'Canada Transportation Act'], and the nature and scope of the “exclusivity principle” set out in Article 29 of the 1999 Convention for the Unification of Certain Rules for International Carriage by Air" [SS: the 'Montreal Convention'].

Here the court engages in a useful consideration of expert evidence doctrine (Mohan/necessity), and foreign and international law (as the object of the evidence inquiry):

[68] Justice de Montigny noted that the case law has not been consistent in its treatment of expert evidence regarding international law. Some appellate courts have taken judicial notice of international law (see Turp v. Canada (Foreign Affairs), 2018 FCA 133, [2019] 1 F.C.R. 198) or have otherwise considered questions of customary and conventional international law without recourse to expert evidence (e.g., Suresh v. Canada (Minister of Citizenship and Immigration), 2002 SCC 1, [2002] 1 S.C.R. 3 (considering peremptory norms of international law); Yugraneft Corp., at paras. 19 and 21 (considering the Convention on the Recognition and Enforcement of Foreign Arbitral Awards, Can. T.S. 1986 No. 43)). However, on at least two occasions, courts have admitted expert evidence on questions of international law (Holding Tusculum B.V. v. S.A. Louis Dreyfus & Cie, 2006 QCCS 2827, at para. 16 (CanLII); Fédération des travailleurs du Québec (FTQ - Construction) v. Procureure générale du Québec, 2018 QCCS 4548, at para. 20 (CanLII)).

[69] The appellants, the Attorney General and the Federal Court of Appeal have sought clarification on this issue. I agree that such clarification is timely.

(1) Mohan Governs Expert Evidence on Questions of International Law

[70] The appellants and the Attorney General are, for the most part, ad idem that the Mohan framework be used to determine the admissibility of the expert evidence. The appellants submit that “[e]xpert evidence is necessary when it is likely to provide information outside the judge’s experience and knowledge” (A.F., at para. 107). The appellants submit that it may be “necessary for a court to receive expert evidence where the normative content of international law is unsettled, controversial or emerging” (para. 111). They further argue that Canadian judges may find it difficult to ascertain the content of international law because it implicates practice in foreign states, making expert evidence important in this context. The Attorney General agrees that Mohan governs, but argues that expert evidence on a legal issue before the court is inadmissible as such expert evidence would usurp the court’s role. Justice de Montigny, in weighing these arguments, noted that whether “international law [should] be treated as a question of fact” is “a vexed question” (C.A. reasons, at para. 46).

[71] While some courts of first instance deal infrequently with international law, others do so with more regularity. For example, the Federal Court often encounters international legal issues due to the nature of its jurisdiction. The approach of some courts of first instance to expert evidence has been described as “inconsistent, and often under-reasoned” (G. van Ert, Recent Federal Courts decisions on expert evidence of international law, December 31, 2018 (online); see also G. van Ert, “The Admissibility of International Legal Evidence” (2005), 84 Can. Bar Rev. 31). As a result, clarification of how to determine the admissibility of expert evidence, when such is necessary, may be beneficial.

[72] The test from Mohan should be applied in the context of international law as it is in other circumstances where expert evidence is sought to be admitted. Under the Mohan test, expert evidence is admissible when it is “necessary in the sense that it provides information ‘which is likely to be outside the experience and knowledge of a judge . . .’” (p. 23, quoting R. v. Abbey, 1982 CanLII 25 (SCC), [1982] 2 S.C.R. 24). The test is as follows: At the first stage, judges must consider the threshold requirements of admissibility set out in Mohan. There are four threshold requirements: “. . . (1) relevance; (2) necessity in assisting the trier of fact; (3) absence of an exclusionary rule; and (4) a properly qualified expert . . .” (White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23, [2015] 2 S.C.R. 182, at para. 19, citing Mohan, at pp. 20-25). At the second stage — the discretionary “gatekeeping” stage — judges must balance the potential risks and benefits of admitting the evidence and determine whether the benefits outweigh the risks. Mohan’s “basic structure for the law relating to the admissibility of expert opinion evidence” is applicable in a wide range of contexts outside the experience of judges (White Burgess, at para. 19). See, for example, Masterpiece Inc. v. Alavida Lifestyles Inc., 2011 SCC 27, [2011] 2 S.C.R. 387, at para. 75 (intellectual property); Clayson-Martin v. Martin, 2015 ONCA 596, 127 O.R. (3d) 1 (medical reports); and R. v. Abdullahi, 2021 ONCA 82, 399 C.C.C. (3d) 397, at para. 34 (linguistics and translation).

[73] As with areas of the law such as those noted above, from time to time difficult and contentious questions of international law will arise where judges will be assisted in carrying out their functions by appropriate expert evidence. Questions of conventional international law may require judges to have regard to questions of fact that are susceptible to expert evidence including, inter alia, foreign law (in applying a treaty, for example), state practice in a treaty’s application, or the authentic text of a treaty in a foreign language (see G. van Ert, Using International Law in Canadian Courts (2nd ed. 2008), at pp. 57 and 63). Similarly, in the context of customary international law, “alleged customs may be contested and require proof” (p. 67). Mohan is sufficiently flexible to enable courts to admit expert evidence on such questions, where it is needed for a court to carry out its functions.

[74] To summarize, then, the appropriate framework is the following. Where expert evidence satisfies Mohan’s criteria, it may be considered. Otherwise, judges should proceed as they would for any other question of law — that is, on the basis of the submissions of the parties before the court and authorities on which they rely.

[75] This Court on various occasions has considered the meaning of treaties without recourse to expert evidence, including in Thibodeau and Yugraneft Corp. Looking to the principles of treaty interpretation codified in the Vienna Convention, and undertaking an examination of the text, object, and purpose of a treaty, is within the capacity of Canadian courts.

[76] In Suresh, this Court considered the peremptory norm of international law regarding the prohibition of torture; this required the Court to have regard to international conventions which Canada has ratified and to jus cogens norms of international law. The Court had recourse to academic texts, foreign jurisprudence, as well as the submissions of parties and interveners. These sources sufficed for the Court to consider the status of the prohibition against torture as a matter of international law.

[77] Though the Court did not rely on Mohan in these cases, its approach to dealing with questions of international law without recourse to expert evidence is consistent with Mohan’s suggestion that “[i]f on the proven facts a judge or jury can form their own conclusions without help, then the opinion of an expert is unnecessary” (p. 24).

[78] Finally, I note that evidence law jurisprudence establishes a number of cautionary rules that apply with equal force in the context of expert evidence sought to be admitted regarding international law. First, as noted in Quebec (Attorney General) v. Canada, 2008 FC 713, 359 F.T.R. 1, aff’d 2009 FCA 361, 400 N.R. 323, aff’d 2011 SCC 11, [2011] 1 S.C.R. 368, the role of an expert is “only to assist the court in assessing complex and technical facts. It must never be forgotten that, ultimately, it is the court that must decide questions of law” (para. 161). Furthermore, “[e]xpert opinions will be rendered inadmissible when they are nothing more than the reworking of the argument of counsel participating in the case” (Surrey Credit Union v. Willson (1990), 1990 CanLII 1983 (BC SC), 45 B.C.L.R. (2d) 310 (S.C.), at p. 315).

[79] In applying Mohan, the admissibility of expert evidence is within the court’s discretion so long as the threshold requirements of admissibility are satisfied. Given the variety of contexts in which expert evidence is sought to be adduced on questions of international law, the admissibility of such evidence is best left as a matter of judicial discretion rather than being subject to a fixed and invariable rule.

. International Air Transport Association v. Canada (Transportation Agency)

In International Air Transport Association v. Canada (Transportation Agency) (Fed CA, 2020) the Federal Court of Appeal considered the treatment of international law in Canadian courts:

[14] It is settled law that questions of foreign law are treated as questions of fact, and as such, require proof through the evidence of properly qualified experts. However, the law appears to be somewhat less settled when it comes to the need for expert evidence addressing questions of international law.

[15] This Court commented on the use of expert witnesses to prove matters of international law in Turp v. Canada (Foreign Affairs), 2018 FCA 133, [2019] 1 F.C.R. 198. The Court stated that, in its view, parties do not need to file expert reports to prove international law, as international law is a matter of which Canadian judges can take judicial notice: Turp, at paras. 82-89. See also the cases cited in Turp: The Ship "“North”" v. The King, 1906 CanLII 80 (SCC), [1906] 37 S.C.R. 385, 26 C.L.T. 380; Jose Pereira E Hijos, S.A. v. Canada (Attorney General), 1996 CanLII 4098 (FC), [1997] 2 F.C. 84, (1996), 126 F.T.R. 167 (T.D.); Lord Advocate's Reference No. 1, [2001] ScotHC 15 (BAILII), [2001] S.L.T. 507.

[16] The Court was, however, clear that its comments in Turp were made in obiter, as the parties had not raised the evidentiary issue, and that its comments should thus not be taken to be a definitive ruling on the question.

[17] The Federal Court has also come to a similar conclusion to that reached in Turp with respect to the need for expert evidence regarding issues of international law: Pan American World Airways v. The Queen, 1979 CanLII 2790, 96 D.L.R. (3d) 267, at 274-275 (aff’d without comment on this issue 1980 CanLII 2610 (FCA), [1981] 2 S.C.R. 565 (SCC)).

[18] Indeed, in a series of articles, Gib van Ert argues persuasively that, in contrast to questions of foreign law (which are uniformly treated as questions of fact), matters of public international law are questions of law and as such do not require proof: Gib van Ert," “Recent Federal Court Decisions on Expert Evidence of International Law” "(31 December 2018) online (blog): Gib van Ert ; "“The Reception of International Law in Canada: Three Ways We Might Go Wrong”", (2018) in Centre for International Governance Innovation in Canada in International Law at 150 and Beyond, Paper No. 2; "“The Admissibility of International Legal Evidence"” (2005) 84 Can Bar Rev.

[19] That said, van Ert acknowledges that Canadian courts have been uneven in their evidentiary approach to international legal issues: van Ert, “Three Ways We Might Go Wrong”, above at 6. He cites examples of a contrary approach being taken, including in Bouzari v. Iran (Islamic Republic), [2002] O.J. No. 1624, [2002] O.T.C. 297 (Ont. S.C.J.), aff’d 2004 CanLII 871 (ON CA), 71 O.R. (3d) 675 (Ont. C.A.) and Amaratunga v. Northwest Atlantic Fisheries Organization, 2011 NSCA 73, [2011] N.S.J. No. 453. I note the Federal Court also commented on the unsettled nature of the law on this point in Boily v. Canada, 2017 FC 1021, [2017] F.C.J. No. 1275 at paras. 25, 27-31.

[20] The appellants have also identified cases where a contrary view has been taken of the evidentiary issue, including Holding Tusculum B.V. c. S.A. Louis Dreyfus & Cie, 2006 QCCS 2827, [2006] Q.J. No. 4878. In that case, the Quebec Superior Court dismissed a motion to strike expert reports with respect to international arbitration law that raised arguments similar to those advanced here: paras. 4, 9-10. The disputed evidence was subsequently relied on by the Court in its decision on the merits: Holding Tusculum, b.v. c. Louis Dreyfus, s.a.s. (SA Louis Dreyfus & Cie.), 2008 QCCS 5904, [2008] Q.J. No. 15012.

[21] There have also been a number of cases where expert evidence with respect to international law (including the meaning of treaty obligations) has been accepted, apparently without objection to its admissibility: see, for example, Tracy v. Iranian Ministry of Information and Security, 2016 ONSC 3759, [2016] O.J. No. 3042 (Ont |S.C.J.), aff’d 2017 ONCA 549, leave to appeal to the Supreme Court of Canada ref’d [2017] S.C.C.A. No. 359.

[22] Similarly, in Najafi v. Canada (Public Safety and Emergency Preparedness), evidence of two international law experts as to the legality of the use of force in international law was adduced before the Federal Court, apparently without objection. That evidence informed the analysis of both the Federal Court and of this Court on appeal: 2013 FC 876, aff’d 2014 FCA 262, leave to appeal to the Supreme Court of Canada ref’d [2015] S.C.C.A. No. 2.

[23] A further example of this is found in Saskatchewan v. Saskatchewan Federation of Labour, 2012 SKQB 62. There, the Court of Queen’s Bench for Saskatchewan received expert evidence on Canada’s international treaty obligations with respect to labour relations and the right to strike: paras. 100 and 102. The matter was ultimately appealed to the Supreme Court of Canada. In her majority reasons, Justice Abella referred to the expert evidence on international law adduced by the Saskatchewan Union of Nurses, albeit without comment as to the admissibility of expert evidence on this issue: 2015 SCC 4, at para. 65.

[24] Indeed, as the appellants note, the Attorney General himself has adduced expert evidence with respect to international law issues in numerous cases: see cases listed at paras. 55-56 of the appellants’ memorandum of fact and law.

[25] The Attorney General notes that this Court has been prepared to strike inadmissible evidence at an early stage of the proceedings: Canada (Board of Internal Economy) v. Canada (Attorney General), 2017 FCA 43, [2017] F.C.J. No. 255 [Boulerice]. While the Court did find that the admissibility issue in Boulerice was better resolved at an early stage, this finding was based on the fact that the evidence in question was "“so clearly out of bounds ... that it ought to be stopped in its tracks”". The Court was further satisfied that there was "“simply no point in leaving it on the record, as it is so clearly inadmissible that there is no need to have a full record before coming to a final assessment of its merits”": at para. 30.

[26] What is apparent from the above review of the jurisprudence is that the evidentiary issue raised by the Attorney General’s motion to strike in this case is not as clear-cut as he contends. This suggests that it is preferable to leave the admissibility and necessity issues with respect to the evidence of the appellants’ expert witnesses to be determined by the panel assigned to hear this appeal.

[27] My finding in this regard is supported by the fact that this case is still at a very early stage. The parties have yet to file their memoranda of fact and law on the appeal, with the result that the issues raised by the appeal have yet to be fully fleshed out. The admissibility issues and the centrality of the disputed evidence to the ultimate issue or issues in this case are better determined once those issues have crystalized.

In addition, the court makes the following interesting observation on the role of international law in US courts:

[29] Dr. Dempsey was asked by the appellant, the International Air Transport Association, to provide his opinion on questions of American law relating to air passenger rights. In offering his opinion on these questions, Dr. Dempsey observed that the United States is a "“monist”" jurisdiction, meaning that, unlike the "“dualist”" system that we have in Canada insofar as international treaties are concerned, it is not necessary to enact domestic legislation to implement international treaties into American law. According to Dr. Dempsey, instruments such as the Montreal Convention are "“self-executing”", and are essentially deemed to be part of American law. The distinction between domestic law and international law is thus artificial in the American context, and that an opinion on the proper interpretation of international treaties, including the Montreal Convention, is an opinion on U.S. law.