[2024] UKUT 00281 (IAC)

Where a rule permits, but does not require, consideration of certain matters, as in R (Khatun) and others v London Borough of Newham [2004] EWCA Civ 55, a useful related assessment is that proposed by Schiemann J in R v Nottingham City Council ex parte Costello (1989) 21 HLR 301. The court should establish what material was before the decision-maker and should only strike down a decision by the decision-maker not to make further enquiries, if no reasonable decision-maker in possession of that material could suppose that its enquiries were sufficient.

In considering the application of section 31(2A)of the Senior Courts Act 1981, the Court of Appeal confirmed in R (Plan B Earth) v Secretary of State for Transport [2020] EWCA Civ 214, at §§272 and 273 that first, the matter is not simply one of discretion, but rather becomes one of duty provided the statutory criteria are satisfied. This is subject to a discretion vested in the court nevertheless to grant a remedy on grounds of “exceptional public interest”. Secondly, the outcome does not inevitably have to be the same; it will suffice if it is merely “highly likely”. Thirdly, it does not have to be shown that the outcome would have been exactly the same; it will suffice that it is highly likely that the outcome would not have been “substantially different” for the claimant. That is different from the test for the materiality of an error of law in a statutory appeal, as confirmed in ASO (Iraq) v SSHD [2023] EWCA Civ 1282 at §43, namely whether any rational Tribunal would have been bound to come to the same decision on the evidence before the Tribunal.