Most of the time, when administrative lawyers speak of "deference" they have in mind a standard of review which either gives weight to the conclusions of the administrative decision-maker (epistemic deference) or carves out a space for the administrative decision-maker which a reviewing court will not enter unless the decision is, for example, "unreasonable", or "patently unreasonable", or "so unreasonable that no reasonable person would have reached it" (doctrinal deference). And of course where the standard is correctness, no deference is due and the reviewing court can substitute its judgement for that of the administrative decision-maker.*
Recently, in Re: Sound v. Fitness Industry Council of Canada, 2014 FCA 48, Evans J.A. wrote of the importance of giving weight (epistemic deference) to procedural choices made by administrative decision-makers:
Evans J.A.'s formulation is especially useful because it reminds us that the choice of standards of review is not exhausted by a binary one between correctness and reasonableness. Moreover, epistemic deference is much closer to David Dyzenhaus's "deference as respect", a label which is often used without proper understanding of the underlying concept. And Evans J.A. is not the first Canadian appellate judge to recognize the value of epistemic deference. Recall the 2001 formulation of Lambert J.A. in Northwood v. Forest Practices Board, 2001 BCCA 141: In short, whether an agency’s procedural arrangements, general or specific, comply with the duty of fairness is for a reviewing court to decide on the correctness standard, but in making that determination it must be respectful of the agency’s choices. It is thus appropriate for a reviewing court to give weight to the manner in which an agency has sought to balance maximum participation on the one hand, and efficient and effective decision-making on the other. In recognition of the agency’s expertise, a degree of deference to an administrator’s procedural choice may be particularly important when the procedural model of the agency under review differs significantly from the judicial model with which courts are most familiar.
On this approach, the reviewing court retains the final word, but will be influenced by the weight it gives to the views of the administrative decision-maker. Epistemic deference need not be limited to the task of judicial review; it may be the most appropriate means of conducting internal appellate review. [T]he standard called “correctness” cannot be a rigid one...Indeed judges often feel that they are not right or wrong, correct or incorrect, in a particular case. Rather, they form opinions. Almost all arguments about statutory interpretation in this Court, and indeed arguments about many other questions, consist of reasoned thinking supporting one view or the other. In the end, the judges tend not to say that one argument is correct and the other incorrect. They say that they adopt, accept, or prefer one argument to the other and give their opinions accordingly. So, in the end, it is possible to give one argument greater weight than another in deciding which to prefer. If an argument is made that deference on the interpretation of the statute should be given to those who are experts in its functioning, that does not mean that the standard of “correctness” is being abandoned. What it means is that deference is being given through acceptance of one of the arguments, which, in turn, may decide the balance between the competing arguments, in relation to applying the standard of “correctness”. In such a situation, neither of the competing arguments need be categorized as “wrong”, but only one of them is preferred. That one, but not the other one, then meets the standard of “correctness”. And that argument may be supported by, among other points, a degree of deference to the opinion of the tribunal whose jurisdiction is in issue.
It is notable that Evans J.A. made his comments in the context of procedural fairness (and concluded that procedural fairness was breached in the instant case). The giving of "weight" to administrative decision-makers may calm the fears of those who are anxious that deference to procedural determinations will undermine procedural fairness.
* Some radicals might say that correctness can never truly be the standard of review because the interpretive context is always shaped by the initial conclusions of the administrative decision-maker, such that is impossible for a reviewing court to substitute judgement entirely. This may be true, though its importance lies in the realm of practice rather than that of doctrine.