What is the standard of review for an administrative decision-maker exercising statutory discretion?

Because the subject of this application is a decision made by an administrative decision-maker exercising a statutory discretion, a pragmatic and functional analysis must be undertaken to establish the appropriate standard of review; see Sketchley v. Canada (Attorney General), 2005 FCA 404. Four factors must be considered: the presence or absence of a privative clause; the expertise of the tribunal; the statutory purpose; and the nature of the question.