Administrative - Stare Decisis. Perrin v. Canadian Union of Public Employees
In Perrin v. Canadian Union of Public Employees (Fed CA, 2023) the Federal Court of Appeal considered a JR of a CIRB [Canada Industrial Relations Board] 'duty of fair representation' (s.37 of the Canada Labour Code) decision, here regarding COVID vaccination policy which the union did not grieve:
 The applicants alleged in their complaint that the Union breached its duty by refusing to file a policy grievance challenging Air Canada’s mandatory vaccination policy. The applicants are a group of flight attendants, pursers and service directors employed with Air Canada. Ms. Perrin was mandated to bring the complaint on their behalf.. Ottawa Airport Professional Aviation Fire Fighters Association v. Ottawa Macdonald-Cartier International Airport Authority
 In its decision, the Board found that since the factual considerations and legal arguments raised in the complaint were substantially similar to those reviewed and addressed in its recently issued decision Ingrid Watson v. Canadian Union of Public Employees, 2022 CIRB 1002 [Watson], it could rely on its analysis and rationale. In Watson, it had concluded that the Union had not breached its duty of fair representation when it refused to file a policy grievance with respect to Air Canada’s mandatory vaccination policy. The Board’s decision has since been upheld by this Court in Watson v. Canadian Union of Public Employees, 2023 FCA 48 [Watson FCA].
 ... Moreover, contrary to the applicants’ assertion, the Board did examine the Union’s conduct. It found that the Union had communicated regularly with its membership regarding the implementation of the policy, and that it had turned its mind to the issues raised by the members, including those who disapproved of the policy for various reasons. The Board was not required to refer to every document in the record, to respond to every argument or to make an explicit finding on each element leading to its conclusion (Vavilov at paras. 91, 128; Newfoundland and Labrador Nurses’ Union v. Newfoundland and Labrador (Treasury Board), 2011 SCC 62 at para. 16). There is no basis for concluding that the Board ignored evidence or that it failed to grapple with any of the issues raised by the applicants.
In Ottawa Airport Professional Aviation Fire Fighters Association v. Ottawa Macdonald-Cartier International Airport Authority (Div Court, 2022) the Divisional Court clarifies to limited scope of the doctrine that administrative law is exempt from stare decisis:
 An arbitrator is not bound by stare decisis. However, the Supreme Court of Canada stated in Vavilov that a decision may be unreasonable if it is inconsistent with prior decisions of the administrative tribunal, and that inconsistency is not explained and justified by the decision-maker. As the Court stated (at para. 131):. National Grocers Co. Ltd. V. United Food and Commercial Workers Union, Local 1000A
... a decision that departs from longstanding practices or established internal decisions will be reasonable if that departure is justified, thereby reducing the risk of arbitrariness, which would undermine public confidence in administrative decision makers and in the justice system as a whole.
In National Grocers Co. Ltd. V. United Food and Commercial Workers Union, Local 1000A (Div Court, 2022) the Divisional Court considers the implications of the administrative exemption from the doctrine of stare decisis:
 The reviewing court does not conduct a de novo analysis to determine the “correct” interpretation of the disputed provision: Vavilov, at para. 116. The Supreme Court has acknowledged the legitimacy of multiple reasonable interpretations of statutory language, especially in cases where “the statutory language is less than crystal clear”: British Columbia (Securities Commission) v. McLean, 2013 SCC 67,  3 S.C.R. 895 at para. 37. In the course of reviewing a decision, however, it may become clear that the interplay of text, context and purpose leaves room only for a single reasonable interpretation which is at odds with the interpretation given by the decision maker, or that the decision maker’s interpretation falls outside a range of reasonable outcomes, based on the facts and the law: Vavilov, at para. 124.. Peters First Nation v. Engstrom
In Peters First Nation v. Engstrom (Fed CA, 2021) the Federal Court of Appeal cited how the SCC had undertaken to make it clear when there was only one possible statutory interpretation - given the Vavilov JR 'reasonableness' standard's potential for multiple such interpretations:
 The Supreme Court has consistently held there will be circumstances where the ordinary tools of statutory interpretation will make it clear that there is only one reasonable interpretation (see, e.g., Vavilov at para. 124; Wilson v. Atomic Energy of Canada Ltd., 2016 SCC 29,  1 S.C.R. 770 at para. 35; Canada (Canadian Human Rights Commission) v. Canada (Attorney General), 2011 SCC 53,  3 S.C.R. 471 at para. 64; McLean v. British Columbia (Securities Commission), 2013 SCC 67,  3 S.C.R. 895 at para. 38). This Court, and other appellate courts across Canada have also recognized that reasonableness encompasses situations where there is only one possible interpretation (see, e.g., Nova Tube Inc./Nova Steel Inc. v. Conares Metal Supply Ltd., 2019 FCA 52, 2019 CarswellNat 14755 at para. 61; English v. Richmond (City), 2021 BCCA 442, 2021 CarswellBC 3665 at para. 120; Ontario Nurses’ Association v. Participating Nursing Homes, 2021 ONCA 148, 154 O.R. (3d) 225 at para. 84).. Canada (Attorney General) v. Burke
 For the reasons outlined above, the term "“natural child”" can only have one reasonable meaning. This is not a term for which there is a range of reasonable outcomes.
In Canada (Attorney General) v. Burke (Fed CA, 2022) the Federal Court of Appeal considered an administrative stare decisis (which in this case is also a standard of review (SOR) for judicial review issue), with what I suspect is frustration with the Vavilov doctrine of (seemingly) allowing varying legal interpretations as legitimate (SS: see italics, which are mine). The case reflected a sharp difference in statutory interpretation in the Old Age Security system (an issue which Vavilov requires to be assessed on a 'reasonableness' SOR):
V. Standard of Review. Tang v. Human Rights Tribunal of Ontario
 The standard of review applicable to decisions of the Appeal Division is that of reasonableness: Canada (Attorney General) v. Redman, 2020 FCA 209 at para. 12; Cameron v. Canada (Attorney General), 2018 FCA 100 at para. 3. This includes decisions involving questions of statutory interpretation: Canada (Minister of Citizenship and Immigration) v. Vavilov, 2019 SCC 65, at para. 115.
 This is the case even where there has been persistent discord on questions of law in an administrative body’s decisions: Vavilov, above at paras. 72, 129. Where, however, a decision maker departs from longstanding practices or established internal authority, it bears the justificatory burden of explaining that departure in its reasons. If the decision maker does not satisfy this burden, the decision will be unreasonable: Vavilov, above at para. 131.
 That said, it would be antithetical to the rule of law and would lead to legal incoherence if the meaning of a law was to depend on the identity of the individual decision maker. Rather than considering this to be a situation where the correctness standard of review ought to be applied, however, the Supreme Court stated that the more robust form of reasonableness review described in Vavilov is capable of guarding against threats to the rule of law: Vavilov, above at para. 72.
 In reviewing the interpretation of statutory provisions by administrative tribunals, the reviewing court does not undertake its own, de novo analysis of the question. Nor does it ask itself what the correct interpretation of the legislation should be. Instead, as is the case where a reviewing court is applying the reasonableness standard to questions of fact, discretion or policy, the Court must examine the administrative decision as a whole, including the reasons provided by the decision maker and the outcome that was reached, in order to determine whether the decision was reasonable: Vavilov, above at paras. 75, 83 and 116.
 In so doing, the reviewing court must focus on the decision maker’s interpretation, keeping in mind that there may be more than one reasonable interpretation of legislation available to an administrative decision maker, based on the text, context and purpose of the legislation: Canada (Minister of Citizenship and Immigration) v. Mason, 2021 FCA 156 at paras. 16, 18.
 That said, the decision maker’s interpretation of a statutory provision must be consistent with the text, context and purpose of the provision in question. A decision maker cannot adopt an interpretation it knows to be inferior, even if it is plausible, because the interpretation in question appears to be both available and expedient. The decision maker’s responsibility is to discern meaning and legislative intent, and not to "“reverse-engineer”" its analysis in order to achieve a desired outcome: Vavilov, above at paras. 120, 121.
In Tang v. Human Rights Tribunal of Ontario (Div Ct, 2021) the Divisional Court noted that different legal tests in administrative proceedings was the price we paid for the judicial review 'reasonableness' standard of review:
 As noted by the Supreme Court of Canada in Domtar Inc. v. Quebec (Commission d’appel en matière de lesions preofessionnelles), 1993 CanLII 106 (SCC),  2 SCR 756, a lack of unanimity is the price to pay for the decision-making freedom and independence given to members of these tribunals and that recognizing the existence of a conflict in decisions as an independent basis for judicial review would constitute a serious undermining of that freedom and independence. In Canada (Minister of Citizenship and Immigration) v. Vavilov, 2019 SCC 65, the court affirmed Domtar but added that when a decision maker departs from longstanding practices or established internal authority, it must explain that departure in its reasons and that a failure to do so may render the decision unreasonable.. Mammoet Canada Eastern Ltd. v. International Union of Operating Engineers
In Mammoet Canada Eastern Ltd. v. International Union of Operating Engineers (Div Court, 2022) the Divisional Court applies the administrative 'stare decisis' doctrine from Vavilov, here reviewing a labour arbitrator decision:
 The application of a reasonableness standard of review implicitly recognises that there may be more than one reasonable interpretation of an agreement. . Municipal Property Assessment Corporation v. Claireville Holdings Limited
 To adapt what was said by the Court of Appeal in RBC Dominion Securities, at para. 36, in rejecting its proposed interpretation, the Vice-Chair did not, as the applicant alleges, fail to apply proper contract interpretation principles; rather, he applied the principles, just not in the manner proposed by the applicant.
In Municipal Property Assessment Corporation v. Claireville Holdings Limited (Div Court, 2022) the Divisional Court stated the odd implications of the Vavilov doctrine allowing different tribunal reasoning to apply in different administrative cases:
The Issue of Conflicting Decisions
 MPAC argues that the Board made a third legal error when it determined that the member in Loblaw Properties erred by not following Toronto Airways.
 In my view, this is not a question of law. As noted in Vavilov, administrative decision makers are not bound by their previous decisions in the same sense that courts are bound by stare decisis. The Board’s comments on the merits of the decision in Loblaw Properties were to explain why it preferred the methodology of arriving at a property’s current value as explained in Toronto Airways. It is not a legal error to have done so.