Appeals - Standard of Review (SOR) - Introduction
Note: First, a nomenclature point. For SOR purposes you can equate 'review' (as in SOR) with 'appeal', and vice-versa. While a primary procedural distinction exists between 'appeals' and 'judicial review', the term 'standard of review' applies to both. Be cautious though that the SOR for judicial review is, by it's nature, quite distinct for that for appeals.
Lament: 'Standards of review' are (pointlessly in my view) an essential aspect of contemporary appellate and judicial review law. The added complexity of this issue, especially in judicial reviews, greatly hinders legal accessibility to self-reppers and represented parties alike - all in a dubious claim to conserve judicial energy. I doubt that any judicial time and energy is saved thereby, and the entire 'standard of review' endeavour strikes me as a larger version of the equally pointless 'final versus interlocutory' distinction (which also ostensibly exists as a judicial energy-saving device). While some may argue that 'justiciability' is another reason for the 'standard of review' regime, such argument is arguably sound for judicial review only - not for the appeals we are considering here. In my mind, the only deference due in appeals is that for evidentiary credibility-findings, if in fact credibility is an issue in the case being appealed - which is less and less the case these days.
Introduction'Standards of review' (SOR) are all about deference - that is, the 'benefit of the doubt' that the appeal judge grants to the decision-maker whose decision is being examined in the appeal (ie. the lower court or administrative tribunal). It is essential to note that 'deference' - in the SOR world - means more than an reviewing court's respect for the lower decision-maker's credibility findings, it means (at least consideration of) deference for everything - ie. all aspects of the case: fact, law - and everything in between. This will become plainer to you the more familiar you get with judicial review.
If you read on more in this website, regarding judicial review and the recent (and essential) Vavilov (SCC, 2019) [para 37] case, you'll see that SOR has gotten a lot more complicated these days - but for most appeals it goes relatively simply like this ...
. Standard of Review for Errors of Law
Errors of law are decided on a 'correctness' standard of review. Simply, the appeal judge (actually, it's commonly a panel of judges) decides whether the lower decision-maker made the 'correct' legal decision.
That's no surprise. The law - and Canadians - want and expect the courts to identify and apply 'the law', and it's a unmentioned presumption that it's always the 'same law'. In fact, most people think that all issues should be decided that way: 'correctly', but that's not to be either. Wait til we get to the treatment of judicial review, many of you have a big surprise coming!
. Standards of Review for Errors of Fact
Considering issues of fact - especially if it involves (which classically it does) issues of credibility - are considered by appeal judge/s on the highly-deferential standard of review of 'palpable and overriding error' [Hydro-Québec v. Matta, 2020 SCC 37, at para. 33]:
“An error is palpable if it is plainly seen and if all the evidence need not be reconsidered to identify it, and is overriding if it has affected the result.” It is not in the nature of a “needle in the haystack, but of a beam in the eye.”. Standards of Review for Errors of Mixed Fact and Law
The same 'palpable and overriding error' standard applies to errors of 'mixed law and fact' - but only "where the legal principle is not readily extricable" [Vavilov, para 37]. This latter qualification is really just a caution to make sure that your 'error issue' is truly an irretrievably 'mixed' one.
. Caution: Statutory Standards of Review Take Precedence
If you read Vavilov, you will see how much the issue of justiciability (the power balance between the courts, and the executive/legislative governments) affects the ruling. As such a crucial caution is that when 'assigning' SORs to an issue, that statutory provisions that bear on the issue take precedence - and should be respected [Vavilov, para 37]:
"... should a legislature intend that a different standard of review apply in a statutory appeal, it is always free to make that intention known by prescribing the applicable standard through statute."