In what circumstances would it be inequitable to order a faithless fiduciary to disgorge all profits?

There may well be circumstances where it would be inequitable to order a faithless fiduciary to disgorge all profits. Equity seeks what is fair and what is fair should be determined with flexibility, not by means of hard and fast rules. For that reason, I would not endorse an inflexible rule that full disgorgement of all profits must be ordered in all cases, but nor would I speculate on the sorts of reasons that may justify something less than full disgorgement. I note that Australian courts have grappled with the circumstances in which full disgorgement ought to be made and whether there should be a rebuttable presumption that full disgorgement is appropriate: see e.g. Warman International Ltd v. Dwyer, [1995] HCA 18, at paras. 33-35. I decline to decide these questions today, as counsel for the Appellants failed to address either point.