Public International Law (PUIL). 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. Entertainment Software Assoc. v. Society Composers
 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.
In Entertainment Software Assoc. v. Society Composers (Fed CA, 2020) the Federal Court of Appeal considered a judicial review application where the new s.2.4(1.1) 'making available' of the Copyright Act was at issue. This provision makes it a 'communication of a work' under the Act (for which a SOCAN tariff was payable) to "allow() a member of the public to have access to it from a place and at a time individually chosen by that member of the public". As much of public internet use of copyrighted material is of this nature, the case was quite significant.
An important issue was how international law [here, the WIPO Copyright Treaty] can influence the interpretation of domestic law, an issue with which the Court [Stratas JA] took the oppourtunity to vent it's spleen:
 The respondents defend this approach, urging that we apply the Supreme Court’s decision in Office of the Children’s Lawyer v. Balev, 2018 SCC 16,  1 S.C.R. 398. They submit that, for all practical purposes, Balev makes the Treaty binding in Canadian law. Thus, they submit, the Board’s methodology—interpreting article 8 of the Treaty and then assuming that subsection 2.4(1.1) implemented that interpretation wholesale—was sound. . R v McSween
 Balev says no such thing. In Balev, the Supreme Court considered provincial legislation that adopted and incorporated, explicitly, wholesale and without modification, the Convention on the Civil Aspects of International Child Abduction. Thus, in that case, the statutory interpretation exercise required the Court to interpret the Convention itself. That is different from the case at bar where subsection 2.4(1.1) does not explicitly adopt or incorporate article 8 of the Treaty wholesale and without modification.
 Just because Canadian domestic legislation is enacted against the backdrop of a treaty that Canada has signed and just because the preamble to legislation, as here, suggests that it is aimed at implementing a treaty, it cannot be assumed that Parliament has adopted the treaty wholesale, no more and no less. Parliament, in fact, may have whittled down the provisions of the treaty or may have extended them. Indeed, it may have done something completely different.
 The Board’s decision and many of the submissions supporting it suffer from a misunderstanding of the relationship between Canadian domestic law and international law.
(a) The proper interrelationship between international law and domestic law
 When developing a legal argument, some members of the legal academy, the Bar, administrative decision-makers and the judiciary invoke international law—or sometimes just the vibe of it—because they see it as always relevant, persuasive and binding. Others see it as a make-weight, hoping to sway the impressionable with its grand provenance and sometimes broad acceptance. Still others see it as a supply of preferred values and ideological standards, handy ammunition to fire in support of a cause. In a courtroom ruled by doctrine, these are misuses of international law.
 Too often these days, we see these misuses. International law enters legal debates before courts and administrative decision-makers only in specific, defined ways that are consistent with settled doctrine and our constitutional framework: Gitxaala Nation v. Canada, 2015 FCA 73.
 It is true that some treaties and conventions have been signed by many, some of them most significant. And it is true that prohibitive rules of customary international law do form part of our common law: see R. v. Hape, 2007 SCC 26,  2 S.C.R. 292 at para. 39 and Nevsun Resources Ltd. v. Araya, 2020 SCC 5, 443 D.L.R. (4th) 183. But domestic law—such as a statute, regulation or order in council—that says something different always prevails. For this reason, when domestic law and international law both potentially bear upon a legal problem, one must always start by discerning the authentic meaning of the domestic law.
 Let us not forget why domestic law prevails. In the territory of Canada, the Constitution of Canada is supreme: Constitution Act, 1982, s. 52. Under that Constitution, elected representatives in the federal Parliament and the provincial legislatures have the exclusive right to make laws: sections 91-95 of the Constitution Act, 1867; Canada (Attorney General) v. Northern Inter-Tribal Health Authority Inc., 2020 FCA 63 at para. 31; Williams at para. 49; Canada (Citizenship and Immigration) v. Ishaq, 2015 FCA 151,  1 F.C.R. 686 at para. 26. Under our Constitution, the power to make laws is not vested in anyone else and certainly not the unelected functionaries abroad who draft and settle upon international instruments. Unless legislative power has been properly delegated to the executive, even it does not have the power to make laws: Williams at para. 49: R (Miller) v. Secretary of State for Exiting the European Union,  UKSC 5,  2 W.L.R. 583 at paras. 40-46. Aside from the exceptional power to make laws under the Crown prerogative, a power explicitly preserved by section 9 of the Constitution Act, 1867, we are subject only to legislation passed by those we elect and anyone exercising legislative powers validly delegated to them (see, e.g., Hodge v. The Queen (1883), 9 App. Cas. 117). To be sovereign and autonomous within our territory and to live in a democratic state is to be ruled by laws made by the people we elect.
 For this fundamental reason, international instruments cannot become Canadian law without domestic legislative action. Put another way, international instruments are not self-executing in Canadian domestic law. They must be incorporated into Canadian domestic law by legislation that adopts the international instrument in whole or in part or enacts standards borrowed from or related to that instrument: Capital Cities Comm. v. C.R.T.C., 1977 CanLII 12 (SCC),  2 S.C.R. 141, 81 D.L.R. (3d) 609 at 171-172 S.C.R.; Baker v. Canada (Minister of Citizenship and Immigration), 1999 CanLII 699 (SCC),  2 S.C.R. 817, 174 D.L.R. (4th) 193; and many others. If Parliament decides not to adopt a particular international instrument, that instrument does not become binding domestic law: Ordon Estate v. Grail, 1998 CanLII 771 (SCC),  3 S.C.R. 437, 166 D.L.R. (4th) 193 at para. 137. Those who want it to be binding law have only one recourse: they must persuade some politicians to make it so.
 Sometimes international instruments prompt legislation or influence its terms in whole or in part. Thus, international instruments can play an important role in legislative interpretation, legitimately entering into the analysis of the text, context and purpose of legislation. But this is no result-oriented free-for-all where anything goes: they enter the analysis, but only in specific ways for specific purposes.
 Sometimes the text of a legislative provision explicitly adopts the international instrument wholesale. In such a case, there is no doubt and so the task of legislative interpretation boils down to interpreting the international instrument. Balev is that sort of case.
 Sometimes the text of a legislative provision is ambiguous but international law may have influenced its purpose or context. In such a case, the relevant international instrument should be examined as part of the overall task of discerning the authentic meaning of the legislation. In this context, ambiguity means that the provision is "“reasonably capable of more than one meaning”", has "“two or more plausible readings, each equally in accordance with the intentions of the statute”" or "“the words are ambiguous enough to induce two people to spend good money in backing two opposing views as to their meaning”": Bell ExpressVu at paras. 29-30; Westminster Bank Ltd. v. Zang,  A.C. 182 (H.L.) at 222; CanadianOxy Chemicals Ltd. v. Canada (Attorney General), 1999 CanLII 680 (SCC),  1 S.C.R. 743, 171 D.L.R. (4th) 733 at para. 14; John Willis, "“Statute Interpretation in a Nutshell”" (1938), 16 Can. Bar Rev. 1 at 4-5.
 Sometimes the text of a provision seems clear but there is international law surrounding the subject-matter of the provision. In such a case, one should still examine the international law to see whether there are latent ambiguities in the legislative text to be resolved and, if so, to use it alongside other elements of context and purpose to resolve the latent ambiguity: National Corn Growers Assn. v. Canada (Import Tribunal), 1990 CanLII 49 (SCC),  2 S.C.R. 1324, 74 D.L.R. (4th) 449; Baker; Canada v. Seaboard Lumber Sales Co., 1995 CanLII 3604 (FCA),  3 F.C. 113, 184 N.R. 364 (C.A.); Pembina County Water Resource District v. Manitoba (Government), 2017 FCA 92, 409 D.L.R. (4th) 719. This is nothing more than a particular application of the general rule that even where the legislative text is clear, the context and purpose of the legislation nevertheless must be examined in order to see whether there are latent ambiguities that must be resolved: ATCO Gas & Pipelines Ltd. v. Alberta (Energy & Utilities Board), 2006 SCC 4,  1 S.C.R. 140 at para. 48; Montréal (City) v. 2952-1366 Québec Inc., 2005 SCC 62,  3 S.C.R. 141 at para. 10; see also CIBC World Markets Inc. v. Canada, 2019 FCA 147 at para. 27 and Hillier at para. 24.
 If, after interpreting the domestic legislation in this way, the Court concludes that the legislation is clear and has no patent or latent ambiguities, the Court must give it its authentic meaning and apply it. This must be done even if it conflicts with international law: Németh v. Canada (Justice), 2010 SCC 56,  3 S.C.R. 281 at para. 35; Hape at para. 54; Schreiber v. Canada (Attorney General), 2002 SCC 62,  3 S.C.R. 269 at para. 50; Tapambwa v. Minister of Citizenship and Immigration, 2019 FCA 34, 69 Imm. L.R. (4th) 297; Gitxaala Nation (2015) at para. 16. Given our constitutional arrangements, international law cannot be used to displace or amend the authentic meaning of domestic legislation.
 The consideration of international law in legislative interpretation, like legislative interpretation itself, must be done in a neutral, non-results-oriented, non-tendentious way: Williams at paras. 46, 48; Hillier at para. 26; Sharif at para. 51.
 The foregoing principles apply to administrative decision-makers as well as courts. Like courts, administrative decision-makers must interpret legislation by examining its text, context and purpose: Vavilov at paras. 120-121. As discussed above, under that method, international law enters into the analysis only in certain ways.
 But administrative decision-makers, such as the Board, are different from courts in that they have no inherent or plenary jurisdiction. They have only the powers granted to them explicitly or implicitly by legislation and they must apply only the explicit and implicit standards contained in the legislation that binds them: Chandler v. Alberta Association of Architects, 1989 CanLII 41 (SCC),  2 S.C.R. 848, 62 D.L.R. (4th) 577; Tranchemontagne v. Ontario (Director, Disability Support Program), 2006 SCC 14,  1 S.C.R. 513 at para. 16; Chrysler Canada Ltd. v. Canada (Competition Tribunal), 1992 CanLII 68 (SCC),  2 S.C.R. 394, 92 D.L.R. (4th) 609. Those standards may incorporate international law or allow, even implicitly, international law to be taken into account. As well, unless modified by, inconsistent with or precluded by legislation, rules of customary international law form part of Canadian common law and can be considered by administrative decision-makers in the exercise of their discretion: Vavilov at para. 114; Baker; Hape at para. 39; Nevsun.
 In defence of the Board’s decision, some of the respondents have urged upon us the presumption that domestic legislation conforms with international law. It is true that certain cases speak of a "“presumption of conformity”": see, e.g., Vavilov at para. 182; Hape; GreCon Dimter Inc. v. J.R. Normand Inc., 2005 SCC 46,  2 S.C.R. 401 at paras. 39ff.; Kazemi Estate v. Islamic Republic of Iran, 2014 SCC 62,  3 S.C.R. 176. But the word "“presumption”" can lead some dangerously off track.
 Domestic legislation is presumed to conform with a relevant treaty, just as benefits legislation is presumed to be ameliorative and all legislation should be given a large and liberal interpretation, but the focus, as always, must be on what the legislator actually did in its legislation: Hillier at paras. 37-38. As always, that requires a rigorous, dispassionate and objective search for the authentic meaning of the legislation by analyzing its text, context and purpose.
 Properly seen, the presumption requires the Court and administrative decision-makers to take into account any relevant international law as part of the context surrounding the enactment of legislation, as explained above, unless the legislation is clear to the contrary: B010 v. Canada (Citizenship and Immigration), 2015 SCC 58,  3 S.C.R. 704. But the presumption does not permit those interpreting domestic legislation to leap to the conclusion, without analysis, that its authentic meaning is the same as some international law. Nor does it permit them to twist or amend the authentic meaning of domestic law to make it accord with international law. These would be steps too far: something forbidden under our constitutional arrangements and fundamental orderings.
 Seen in this way, the presence of international law is not an invitation for us to depart from the normal, accepted method of interpreting legislation; rather, in certain, defined circumstances, international law is appropriately considered as part of that method.
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.