Public International Law - Interpretation Issues. International Air Transport Association v. Canadian Transportation Agency
In International Air Transport Association v. Canadian Transportation Agency (Fed CA, 2022) the Federal Court of Appeal noted that Canadian legislation is presumed to be consistent with international law, including treaties and customary international law - unless there is 'clear language to the contrary':
 Relying on the presumptions of compliance with international law and of legislative coherence, the appellants submit that section 86.11 can and should be construed as only authorizing regulations that are consistent with Canada’s obligation under international law.. Brown v. Canada (Citizenship and Immigration)
 There is no doubt that Parliament must be presumed not to have intended to adopt legislation inconsistent with Canada’s international obligations under treaty or customary international law: see, for example, R. v. Appulonappa, 2015 SCC 59 (CanLII),  3 S.C.R. 754, 478 N.R. 3 at para. 40; Hape at paras. 53-54; R. Sullivan, The Construction of Statutes, 6th ed. (Markham, ON: LexisNexis, 2014), paras. 18.5-18.7 (Sullivan). The Supreme Court explicitly reiterated this principle in the context of the Montreal Convention: see Thibodeau at paras. 6 and 113. In the absence of clear language to the contrary, a statute must be construed as only authorizing subordinate legislation that is respectful of Canada’s international obligations.
 As mentioned earlier, it is a well established principle of statutory interpretation that legislation is presumed to be in conformity with Canada’s international obligations under treaty or customary international law. For that reason, courts will strive to avoid constructions of domestic law that would result in violation of those obligations, unless it is unavoidable. To come to that conclusion, the statute must demonstrate "“an unequivocal legislative intent to default on an international obligation”": Hape at para. 53.
 The Supreme Court expanded on the notion of conflicting legislation in Thibodeau, precisely in a context involving the Montreal Convention. In that case, the Supreme Court made it clear that a conflict will be found when two provisions are "“incapable of standing together”", and when "“the application of one law excludes the application of the other”": Thibodeau at paras. 94 and 96. The Court went on to say that overlapping provisions do not necessarily conflict, so long as they can both apply, unless there is evidence to the effect that one of the provisions was meant to provide an exhaustive declaration of the applicable law: Thibodeau at para. 98. Since interpretations which result in conflict should be eschewed as much as possible unless it is unavoidable, courts will be "“slow to find that broadly worded provisions were intended to be an exhaustive declaration of the applicable law where the result of that conclusion creates rather than avoids conflict”": Thibodeau at para. 99.
 Applying these principles, the majority in Thibodeau found that the Montreal Convention does not permit an award of damages for breach of language rights during international carriage by air, and that to hold otherwise would be both contrary to the text and purpose of that convention, and would be inconsistent with a "“strong international consensus”" concerning its scope and effect: Thibodeau at para. 6. Accordingly, the majority interpreted the general remedial power under subsection 77(4) of the Official Languages Act, R.S.C. 1985, c. 31 (the OLA), as not authorizing an award of damages so as to avoid a conflict that was not inescapable. The Supreme Court thereby confirmed the decision of this Court that there is no conflict between the two regimes, since a court must not award damages in circumstances to which the Montreal Convention applies when determining whether a remedy is "“appropriate and just”" under subsection 77(4) of the OLA.
 ... The case law is replete with clear statements that courts, when choosing among possible interpretations, must avoid an interpretation that would put Canada in breach of its international obligations: see Sullivan at § 18.6 and case law referred to.
In Brown v. Canada (Citizenship and Immigration) (Fed CA, 2020) the Federal Court of Appeal sets out the role of international law in the interpretation of Canadian law:
 There is a well-established presumption that, where possible, Canada’s domestic legislation should be interpreted to conform to international law (R. v. Hape, 2007 SCC 26,  2 S.C.R. 292 at para. 53 (Hape)). "“Where possible”" is a key qualifier (Entertainment Software Assoc. at paras. 76-92). Absent contrary indication, legislative provisions are also presumed to observe "“the values and principles of customary and conventional international law”" (Hape at para. 53; B010 v. Canada (Citizenship and Immigration), 2015 SCC 58,  3 S.C.R. 704 at para. 47; Sullivan on the Construction of Statutes at §18.6; see also de Guzman v. Canada (Minister of Citizenship and Immigration), 2005 FCA 436,  3 F.C.R. 655 at paras. 82–87 and Entertainment Software Assoc. at paras. 89-90).. R v McSween
 Therefore, both Canada’s international treaty obligations and the principles underlying international law can play a role in the interpretation of Canadian laws. This is reinforced by paragraph 3(3)(f) of the IRPA, which directs that the Act "“is to be construed and applied in a manner that […] complies with international human rights instruments to which Canada is signatory.”"
 There is, however, an important counterweight to these principles—the doctrine of Parliamentary supremacy. An unambiguous provision must be given effect even if it is contrary to Canada’s international obligations or international law (Németh v. Canada (Justice), 2010 SCC 56,  3 S.C.R. 281 at para. 35; Schreiber v. Canada (Attorney General), 2002 SCC 62,  3 S.C.R. 269 at para. 50; National Corn Growers Assn. v. Canada (Import Tribunal), 1990 CanLII 49 (SCC),  2 S.C.R. 1324, 74 D.L.R. (4th) 449 at 1371; Gitxaala Nation v. Canada, 2015 FCA 73 at para. 16; Hape at para. 54; and see generally the comprehensive discussion in Entertainment Software Assoc. at paras. 76-92).
In R v McSween (Ont CA, 2020) the Court of Appeal explained how Canadian domestic law applies it's international obligations:
 Canadian law is presumed to conform with Canada’s international obligations: R. v. Hape, 2007 SCC 26,  2 S.C.R. 292 at paras. 53-54; Sullivan, at § 18.5. As such, international law can help define the scope of Canadian domestic law. This was the case in Canadian Foundation for Children, Youth, and the Law v. Canada (Attorney General), 2004 SCC 4,  1 S.C.R. 76, where, at paras. 31-33, McLachlin C.J.C. looked to Canada’s international treaty obligations to determine with further precision the definition of what is “reasonable in the circumstances” under s. 43 of the Criminal Code.. Office of the Children’s Lawyer v. Balev
In Office of the Children’s Lawyer v. Balev (SCC, 2018) the Supreme Court of Canada canvassed the Canadian interpretation of international treaties [at paras 36-74 these treaty principles are applied to the Hague Convention]:
B. Principles of Treaty Interpretation
 The Hague Convention is implemented in Ontario by s. 46(2) of the Children’s Law Reform Act, R.S.O. 1990, c. C.12. Since the purpose of that section is to implement the underlying convention, this Court must adopt an interpretation consistent with Canada’s obligations under it: see Pushpanathan v. Canada (Minister of Citizenship and Immigration), 1998 CanLII 778 (SCC),  1 S.C.R. 982, at para. 51.
 Canada is a party to the Vienna Convention on the Law of Treaties, Can. T.S. 1980 No. 37 (“Vienna Convention”), which provides that “[a] treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose”: Article 31(1); see also Crown Forest Industries Ltd. v. Canada, 1995 CanLII 103 (SCC),  2 S.C.R. 802, at para. 22. These international principles generally parallel the domestic approach to statutory interpretation: see R. Sullivan, Statutory Interpretation (3rd ed. 2016), at p. 279.
 A clear purpose of multilateral treaties is to harmonize parties’ domestic laws around agreed-upon rules, practices, and principles. The Hague Convention was intended to establish procedures common to all the contracting states that would ensure the prompt return of children: see preamble. The objective of multilateral treaty making “would be seriously weakened if the courts of every country interpreted [the treaty at issue] without any regard to how it was being interpreted and applied elsewhere”: Connaught Laboratories Ltd. v. British Airways (2002), 2002 CanLII 4642 (ON SC), 61 O.R. (3d) 204 (S.C.J.), at para. 46. To avoid frustrating the harmonizing purpose behind the Hague Convention, domestic courts should give serious consideration to decisions by the courts of other contracting states on its meaning and application: see Vienna Convention, Article 31(3)(b); Thibodeau v. Air Canada, 2014 SCC 67,  3 S.C.R. 340, at para. 50; Stag Line, Limited v. Foscolo, Mango and Co.,  A.C. 328 (H.L.), at p. 350; Scruttons Ltd. v. Midland Silicones Ltd.,  A.C. 446 (H.L.), at p. 471; Air France v. Saks, 470 U.S. 392 (1985), at pp. 403-4; L.K. v. Director-General, Department of Community Services,  HCA 9, 237 C.L.R. 582, at para. 36.
 The parties before us raised two further interpretive issues. The first is whether the Hague Convention conflicts with the Convention on the Rights of the Child, Can. T.S. 1992 No. 3 (“CRC”). For present purposes, there is no conflict between the two conventions. Both conventions seek to protect the best interests of children — the one by deterring child abduction and promoting prompt resolution of custody disputes, and the other by ensuring that decision making focuses on the best interests of the child. Both conventions seek to protect the child’s identity and family relations. The Hague Convention does this by mandating the return of a child to the place of his or her habitual residence (Article 3) so that a custody determination may be made in that place — a place normally central to a child’s identity; Article 8 of the CRC rests on the same policy. Both conventions seek to prevent the illicit transfer and retention of children: see CRC, Article 11; United Nations Children’s Fund, Implementation Handbook for the Convention on the Rights of the Child (rev. 3rd ed. 2007), by R. Hodgkin and P. Newell, at pp. 143-47. And both conventions accept the principle that a child of sufficient maturity should have a say in where the child lives, as discussed below in connection with Article 13(2) of the Hague Convention.
 The second issue raised is whether the Hague Convention should be interpreted consistently with the Canadian Charter of Rights and Freedoms, and in particular the s. 6 guarantee of right of return and the s. 7 guarantee of liberty and security of person. The answer is no. The Charter cannot be used to interpret the Hague Convention or any international agreement: see Febles v. Canada (Citizenship and Immigration), 2014 SCC 68,  3 S.C.R. 431, at para. 64; Vienna Convention, Articles 27 and 31. In any event, when the Hague Convention is interpreted as set out in these reasons, no conflict with ss. 6 or 7 of the Charter is made out.