What is the test for a request for special costs in the context of the Attorney General's decision not to defend the legality of federal legislation?

With respect of the appellant’s request for an order for special costs on a full indemnity basis whether the appeal is allowed or dismissed, as explained in Carter v. Canada (Attorney General), 2015 SCC 5, [2015] 1 S.C.R. 331, special costs are available only if the case involves “matters of public interest that are truly exceptional” (para. 140). In my view, this case does not reach this high standard. The determination of whether a law is ultra vires of the level of government that adopted it is fairly routine. While it is unusual that the Attorney General of Canada decided not to defend the legality of federal legislation, this situation is not sufficient to render the circumstances of the case “exceptional”. Given my conclusion on the first criteria, it is unnecessary to address the second requirement for special costs. IV. Disposition