What is the standard of review for an employment tribunal case?

The majority in Dunsmuir advised that the approach to be taken in determining the appropriate standard of review involves two steps. The first is for the reviewing court to ascertain whether the degree of deference has been satisfactorily determined by the case law with respect to a particular category of question. If it has not, the court is then to take a contextual analysis of the four factors outlined in Pushpanathan v. Canada (Minister of Employment and Immigration), 1998 CanLII 778 (SCC), [1998] 1 S.C.R. 982, including: 1. the presence or absence of a privative clause or statutory right of appeal 2. the purpose of the legislation and the tribunal as determined by the interpretation of its enabling legislation 3. the nature of the question at issue 4. the expertise of the tribunal.