A breach of procedural fairness will generally result in a reviewing tribunal or court remitting the matter back for reconsideration.
There is, however, an extremely narrow exception to this known as the Mobil Oil principle. In Mobil Oil, the Supreme Court of Canada decided not to send a case back for redetermination because the matter that would have been the subject of redetermination was not the subject of the remedies sought, and it was determined to be impractical to send it back. The reason was that the Court had already decided on cross appeal, and that the plaintiffs would thus necessarily lose upon redetermination.
The Mobil Oil principle is thus that while ordinarily an apparent futility of remedy will not bar its recognition, there are cases in which no relief will be offered in the face of breached administrative law principles, such as those which have an inevitable answer. Where a tribunal must decide according to law, it may be justifiable to disregard a breach of natural justice where the demerits of the claim are such that it would in any case be hopeless.
As noted in Persuaid v. Canada, the principle is not that a reviewing tribunal or court can refuse to send a case back because it supposes that the case would be found to be futile. Rather, it may only do so where the remedy sought would not be relevant in the context of the matter presently before the Court. If the remedy sought by the applicant is precisely the remedy affected by the lack of natural justice and procedural fairness, then the reviewing panel or judge should not presume what the result would be nor should it prejudge a case as hopeless.