In Canada (Minister of Citizenship and Immigration) v. Vavilov, 2019 SCC 65, the Supreme Court of Canada, redefined the standard of reasonableness as it pertains to appellate review.
The Court stated:
[101] What makes a decision unreasonable? We find it conceptually useful here to consider two types of fundamental flaws. The first is a failure of rationality internal to the reasoning process. The second arises when a decision is in some respect untenable in light of the relevant factual and legal constraints that bear on it. There is however, no need for reviewing courts to categorize failures of reasonableness as belonging to one type or the other. Rather, we use these descriptions simply as a convenient way to discuss the types of issues that may show a decision to be unreasonable.
1) A Reasonable Decision Is Based on an Internally Coherent Reasoning
[102] To be reasonable, a decision must be based on reasoning that is both rational and logical. It follows that a failure in this respect may lead a reviewing court to conclude that a decision must be set aside. Reasonableness review is not a “line-by-line treasure hunt for error”: Irving Pulp & Paper, at para. 54, citing Newfoundland Nurses, at para. 14. However, the reviewing court must be able to trace the decision maker’s reasoning without encountering any fatal flaws in its overarching logic, and it must be satisfied that “there is [a] line of analysis within the given reasons that could reasonably lead the tribunal from the evidence before it to the conclusion at which it arrived”: Ryan, at para. 55; Southam, at para. 56. Reasons that “simply repeat statutory language, summarize arguments made, and then state a peremptory conclusion” will rarely assist a reviewing court in understanding the rationale underlying a decision and “are no substitute for statements of fact, analysis, inference and judgment”: R. A. Macdonald and D. Lametti, “Reasons for Decision in Administrative Law” (1990), 3 C.J.A.L.P. 123, at p. 139; see also Gonzalez v. Canada (Minister of Citizenship and Immigration), 2014 FC 750, 27 Imm. L.R. (4th) 151, at paras. 57-59.
[103] While, as we indicated earlier (at paras. 89-96), formal reasons should be read in light of the record and with due sensitivity to the administrative regime in which they were given, a decision will be unreasonable if the reasons for it, read holistically, fail to reveal a rational chain of analysis or if they reveal that the decision was based on an irrational chain of analysis: see Wright v. Nova Scotia (Human Rights Commission), 2017 NSSC 11, 23 Admin. L.R. (6th) 110; Southam, at para. 56. A decision will also be unreasonable where the conclusion reached cannot follow from the analysis undertaken (see Sangmo v. Canada (Citizenship and Immigration), 2016 FC 17, at para. 21 (CanLII)) or if the reasons read in conjunction with the record do not make it possible to understand the decision maker’s reasoning on a critical point (see Blas v. Canada (Citizenship and Immigration), 2014 FC 629, 26 Imm. L.R. (4th) 92, at paras. 54-66; Reid v. Criminal Injuries Compensation Board, 2015 ONSC 6578; Lloyd v. Canada (Attorney General), 2016 FCA 115, 2016 D.T.C. 5051; Taman v. Canada (Attorney General), 2017 FCA 1, [2017] 3 F.C.R. 520, at para. 47).
[104] Similarly, the internal rationality of a decision may be called into question if the reasons exhibit clear logical fallacies, such as circular reasoning, false dilemmas, unfounded generalizations or an absurd premise. This is not an invitation to hold administrative decision makers to the formalistic constraints and standards of academic logicians. However, a reviewing court must ultimately be satisfied that the decision maker’s reasoning “adds up”.
(2) A Reasonable Decision Is Justified in Light of the Legal and Factual Constraints That Bear on the Decision
[105] In addition to the need for internally coherent reasoning, a decision, to be reasonable, must be justified in relation to the constellation of law and facts that are relevant to the decision: Dunsmuir, at para. 47; Catalyst, at para. 13; Nor-Man Regional Health Authority, at para. 6. Elements of the legal and factual contexts of a decision operate as constraints on the decision maker in the exercise of its delegated powers.
[106] It is unnecessary to catalogue all of the legal or factual considerations that could constrain an administrative decision maker in a particular case. However, in the sections that follow, we discuss a number of elements that will generally be relevant in evaluating whether a given decision is reasonable, namely the governing statutory scheme; other relevant statutory or common law; the principles of statutory interpretation; the evidence before the decision maker and facts of which the decision maker may take notice; the submissions of the parties; the past practices and decisions of the administrative body; and the potential impact of the decision on the individual to whom it applies. These elements are not a checklist for conducting reasonableness review, and they may vary in significance depending on the context. They are offered merely to highlight some elements of the surrounding context that can cause a reviewing court to lose confidence in the outcome reached.
[107] A reviewing court may find that a decision is unreasonable when examined against these contextual considerations. These elements necessarily interact with one another: for example, a reasonable penalty for professional misconduct in a given case must be justified both with respect to the types of penalties prescribed by the relevant legislation and with respect to the nature of the underlying misconduct.
In light of the presumption of consistent expression, these points are now the legal considerations for reasonableness in all areas and levels of appellate review.
The Court stated:
[101] What makes a decision unreasonable? We find it conceptually useful here to consider two types of fundamental flaws. The first is a failure of rationality internal to the reasoning process. The second arises when a decision is in some respect untenable in light of the relevant factual and legal constraints that bear on it. There is however, no need for reviewing courts to categorize failures of reasonableness as belonging to one type or the other. Rather, we use these descriptions simply as a convenient way to discuss the types of issues that may show a decision to be unreasonable.
1) A Reasonable Decision Is Based on an Internally Coherent Reasoning
[102] To be reasonable, a decision must be based on reasoning that is both rational and logical. It follows that a failure in this respect may lead a reviewing court to conclude that a decision must be set aside. Reasonableness review is not a “line-by-line treasure hunt for error”: Irving Pulp & Paper, at para. 54, citing Newfoundland Nurses, at para. 14. However, the reviewing court must be able to trace the decision maker’s reasoning without encountering any fatal flaws in its overarching logic, and it must be satisfied that “there is [a] line of analysis within the given reasons that could reasonably lead the tribunal from the evidence before it to the conclusion at which it arrived”: Ryan, at para. 55; Southam, at para. 56. Reasons that “simply repeat statutory language, summarize arguments made, and then state a peremptory conclusion” will rarely assist a reviewing court in understanding the rationale underlying a decision and “are no substitute for statements of fact, analysis, inference and judgment”: R. A. Macdonald and D. Lametti, “Reasons for Decision in Administrative Law” (1990), 3 C.J.A.L.P. 123, at p. 139; see also Gonzalez v. Canada (Minister of Citizenship and Immigration), 2014 FC 750, 27 Imm. L.R. (4th) 151, at paras. 57-59.
[103] While, as we indicated earlier (at paras. 89-96), formal reasons should be read in light of the record and with due sensitivity to the administrative regime in which they were given, a decision will be unreasonable if the reasons for it, read holistically, fail to reveal a rational chain of analysis or if they reveal that the decision was based on an irrational chain of analysis: see Wright v. Nova Scotia (Human Rights Commission), 2017 NSSC 11, 23 Admin. L.R. (6th) 110; Southam, at para. 56. A decision will also be unreasonable where the conclusion reached cannot follow from the analysis undertaken (see Sangmo v. Canada (Citizenship and Immigration), 2016 FC 17, at para. 21 (CanLII)) or if the reasons read in conjunction with the record do not make it possible to understand the decision maker’s reasoning on a critical point (see Blas v. Canada (Citizenship and Immigration), 2014 FC 629, 26 Imm. L.R. (4th) 92, at paras. 54-66; Reid v. Criminal Injuries Compensation Board, 2015 ONSC 6578; Lloyd v. Canada (Attorney General), 2016 FCA 115, 2016 D.T.C. 5051; Taman v. Canada (Attorney General), 2017 FCA 1, [2017] 3 F.C.R. 520, at para. 47).
[104] Similarly, the internal rationality of a decision may be called into question if the reasons exhibit clear logical fallacies, such as circular reasoning, false dilemmas, unfounded generalizations or an absurd premise. This is not an invitation to hold administrative decision makers to the formalistic constraints and standards of academic logicians. However, a reviewing court must ultimately be satisfied that the decision maker’s reasoning “adds up”.
(2) A Reasonable Decision Is Justified in Light of the Legal and Factual Constraints That Bear on the Decision
[105] In addition to the need for internally coherent reasoning, a decision, to be reasonable, must be justified in relation to the constellation of law and facts that are relevant to the decision: Dunsmuir, at para. 47; Catalyst, at para. 13; Nor-Man Regional Health Authority, at para. 6. Elements of the legal and factual contexts of a decision operate as constraints on the decision maker in the exercise of its delegated powers.
[106] It is unnecessary to catalogue all of the legal or factual considerations that could constrain an administrative decision maker in a particular case. However, in the sections that follow, we discuss a number of elements that will generally be relevant in evaluating whether a given decision is reasonable, namely the governing statutory scheme; other relevant statutory or common law; the principles of statutory interpretation; the evidence before the decision maker and facts of which the decision maker may take notice; the submissions of the parties; the past practices and decisions of the administrative body; and the potential impact of the decision on the individual to whom it applies. These elements are not a checklist for conducting reasonableness review, and they may vary in significance depending on the context. They are offered merely to highlight some elements of the surrounding context that can cause a reviewing court to lose confidence in the outcome reached.
[107] A reviewing court may find that a decision is unreasonable when examined against these contextual considerations. These elements necessarily interact with one another: for example, a reasonable penalty for professional misconduct in a given case must be justified both with respect to the types of penalties prescribed by the relevant legislation and with respect to the nature of the underlying misconduct.
In light of the presumption of consistent expression, these points are now the legal considerations for reasonableness in all areas and levels of appellate review.