Reasonableness Prevails, but It’s Starting to Look Like Correctness: Mason v. Canada

Key Takeaways

  1. Reasonableness remains the presumptive standard of review in all judicial review cases, and the exceptions are very limited.
  2. Even where the standard of review is reasonableness, there may be situations where only one outcome or decision is reasonable in the circumstances.
  3. Tribunals and decision makers’ reasons should expressly address every relevant argument that a party makes.
  4. The relevant legal constraints that an administrative decision must consider may be broader than previously thought.
  5. A court should not consider the statutory scheme or legal “lay of the land” before reviewing the reasons.


In 2019, the Supreme Court of Canada (the “Court”) released its much-awaited decision in Canada (Minister of Citizenship and Immigration) v. Vavilov.[1] Vavilov held that reasonableness will be the presumptive standard of review in all administrative law cases, unless the legislature intends otherwise or the rule of law requires correctness review. The Court’s recent decision in Mason v. Canada (Citizenship and Immigration)[2] aims to provide some clarification on what exceptions exist to the presumption of reasonableness review and how a reasonableness review should look.


Earl Mason and Seifeslam Dleiow were both charged with violent offences under the Criminal Code. Mason’s charges were eventually stayed because of delay, while Dleiow had some charges stayed and pled guilty to others.

Immigration officers alleged that both men were inadmissible to Canada under s. 34(1)(e) of the Immigration and Refugee Protection Act (“IRPA”),[3] which provides that “[a] permanent resident or a foreign national is inadmissible on security grounds for [...] engaging in acts of violence that would or might endanger the lives or safety of persons in Canada…”

Both men argued that s. 34(1)(e) relates only to national security and not to ordinary violent acts without a national security connection. The Immigration Appeal Division disagreed, concluding that inadmissibility under s. 34(1)(e) does not require a link to national security, but relates to “security in the broader sense” of protecting Canadians from acts of violence.

On judicial review, the Federal Court overturned the decisions, but certified the question as one of “general importance” for review by the Federal Court of Appeal (“FCA”). The FCA reinstated the tribunal’s decision.

Decision and Analysis

Reasonableness Prevails

The Court held that a question will only be of central importance to the legal system – and therefore reviewable for correctness – if it affects other statutes, tribunals or institutions of government. The issue in this case was not a general question of central importance to the legal system as a whole, even though it was important to the interpretation of the IRPA and immigration law.

The Court also held that the Federal Court certifying a question as one of “general importance” under s. 74(d) of the IRPA does not change the standard of review from reasonableness to correctness. Similar provisions in other statutes would also not change the standard of review.


Mason confirms the trend that Vavilov started: correctness will very much be the exception for standards of review. Vavilov was meant to bring about consistency and predictability in choosing standards of review, with a strong presumption that the standard will be reasonableness. Mason held firm to this.

It is helpful to know that the “general questions of importance to the legal system as a whole” exception will not apply where the question is important only to one statute or governmental agency. It seems, based on Mason, that a decision will only get to correctness review under this exception where it will affect other statutes, tribunals or agencies.

Reviewing Courts Must Start With the Reasons, Not a “Lay of the Land”

In keeping with Vavilov’s emphasis on a “reasons-first” approach, the Court in Mason was critical of the FCA’s decision to conduct “a preliminary analysis” of the statutory regime to “understand the lay of the land” before examining the tribunal’s reasons. The Court cautioned that such an approach risks slipping into a correctness review.


This part of the decision may raise some eyebrows among lawyers and judges. After all, if the tribunal is required to consider the rest of the statute in interpreting a provision, how can a court review the decision without looking at the legislation and legal landscape?

The best way to understand this “reasons-first” emphasis might be that it’s more about order than methodology. Of course, a judge is going to consider the rest of the statute and relevant legislation, but Mason says they should only do so after looking at the reasons. Will this make a difference in the outcome? It’s hard to say, but it will be interesting to watch how this develops in future cases.

Reasons Must Account for All Relevant Arguments

The Court found that the tribunal failed to address relevant arguments that parties had made. Mason argued that the tribunal’s interpretation was absurd, since it made deportation more likely than if he had actually been convicted (which would fall under a different provision) and it could lead to deportation for any violent act, even a “schoolyard fight.”

The Court held that the FCA was wrong to have read the tribunal’s decision as implicitly responding to these arguments, reiterating the point from Vavilov that a reviewing court must not “substitute its own justification for the outcome.” It held that a reviewing court must look only to the reasons actually provided and should not assume that the tribunal has considered things not expressly discussed in the reasons.


The Court did not take a forgiving – or even particularly deferential – approach to reasonableness review in this case. Certainly, the fact that the tribunal was considering deportation meant that it had to provide more thorough reasons than other tribunals might need to in situations with lower stakes. Nevertheless, if a tribunal or decision maker wants to be upheld, even on reasonableness review, it is safest to expressly address every relevant argument in the reasons.

Only One Reasonable Interpretation May Remain

On the strength of its finding in Vavilov that, even in a reasonableness review, the relevant constraints may leave room for “only one reasonable interpretation of the provision at issue,” the Mason Court found that the only reasonable interpretation of s. 34(1)(e) was that the provision requires a connection to national security.


It may be counter-intuitive at first to think that reasonableness review, which has traditionally considered the “range of reasonable outcomes,” could mandate a single decision. After all, isn’t that just correctness review? It’s worth noting that the question in this case required a yes or no answer. In other contexts, where there’s a greater range of possible outcomes, it seems unlikely that a court would so willingly say that there can only be one reasonable answer. Still, this may bolster some challenges to administrative decisions that otherwise could only succeed on a correctness standard.

Please contact a member of our Litigation & Dispute Resolution Group for further updates and advice on judicial reviews and administrative law matters.

[1] 2019 SCC 65 [Vavilov].

[2] 2023 SCC 21 [Mason].

[3] SC 2001, c 27.