What is the scope of discretion of the Commissioner's discretion in dealing with allegations of fraud and corruption?

In finding that the Commissioner is entitled to a very broad margin of appreciation in this case, I do not suggest for a moment that he is anything close to immune from review. His discretion is not absolute or untrammelled. Even the broadest grant of statutory power must be exercised in good faith, in accordance with the purposes of the provision, the governing statute and the Constitution: In public regulation of this sort there is no such thing as absolute and untrammelled “discretion”, that is that action can be taken on any ground or for any reason that can be suggested to the mind of the administrator; no legislative Act can, without express language, be taken to contemplate an unlimited arbitrary power exercisable for any purpose, however capricious or irrelevant, regardless of the nature or purpose of the statute. Fraud and cor­ruption in the Commission may not be mentioned in such statutes but they are always implied as exceptions. “Discretion” necessarily implies good faith in discharging public duty; there is always a perspective within which a statute is intended to operate; and any clear departure from its lines or objects is just as objectionable as fraud or corruption. (Roncarelli v. Duplessis, 1959 CanLII 50 (SCC), [1959] S.C.R. 121 at page 140, 16 D.L.R. (2d) 689.)