In 2813127 Ontario Inc. v. His Majesty the King (Div Court, 2023) the Divisional Court directly addressed an issue that I have found elusive of attention, that of the standard of review of a purely legal (here, statutory) issue under the JR 'reasonableness' standard from Vavilov:
 The court charged with a reasonableness review must defer to any reasonable interpretation of the legislation, even if other reasonable interpretations may exist. Judicial deference in such instances is itself a principle of modern statutory interpretation. (McLean v. British Columbia, 2013 SCC 67 at para 40; Vavilov, at para. 235.)
The result is apparently that 'reasonableness' is one over-riding standard for all of: legal issues, issues of mixed fact and law, and issues of fact.
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