What is the standard of review of a decision of a statutory tribunal?

The leading authority on determining the standard of review of a decision of a statutory tribunal is the majority judgment in Dunsmuir v. New Brunswick, 2008 SCC 9, [2008] S.C.J. No. 9. The majority, per Bastarache and Lebel JJ., set out two standards of review: reasonableness, where some level of deference is called for, and correctness, where no deference is required. The majority summarized the relevant process and considerations in determining the standard of review at paras. 62 and 64: In summary, the process of judicial review involves two steps. First, courts ascertain whether the jurisprudence has already determined in a satisfactory manner the degree of deference to be accorded with regard to a particular category of question. Second, where the first inquiry proves unfruitful, courts must proceed to an analysis of the factors making it possible to identify the proper standard of review. .... The analysis must be contextual. As mentioned above, it is dependent on the application of a number of relevant factors, including: (1) the presence or absence of a privative clause; (2) the purpose of the tribunal as determined by interpretation of enabling legislation; (3) the nature of the question at issue, and; (4) the expertise of the tribunal. In many cases, it will not be necessary to consider all of the factors, as some of them may be determinative in the application of the reasonableness standard in a specific case.