Lewis J in R (Lupepe) v SSHD (2017) EWHC 2690 (Admin) considers (paragraphs 48/49) the principle that it is unreasonable, in the public law sense, to disagree with a factual conclusion of an adjudicator who has heard the evidence unless the adjudicator’s conclusion is itself unlawful as a matter of public law (or unless fresh material has become available since the hearing). An illustration of the principle is the decision of the Court of Appeal in R v Warwickshire County Council ex p Powergen (1996) 97 LGR 617 where the Court of Appeal held that a highway authority could not depart from the decision of a planning inspector on a planning appeal that a particular development did not give rise to highway safety issues and it could not act on the basis that the proposed development would create highway dangers.
Lewis J also considered (paragraphs 61-66 inclusive) the position with respect to unpublished policies and (paragraphs 67-69 inclusive) procedural fairness (opportunity to make representations). The law governing the application of unpublished policies was considered by the Supreme Court in R (Lumba) v Secretary of State for the Home Department (JUSTICE intervening) [2012] 1 AC 245. The Supreme Court concluded that what must be published “is that which a person who is affected by a policy needs to know in order to make informed and meaningful representations to the decision-maker before a decision is made”. Where there is a policy in existence, and its provisions are material to the exercise of a discretion in a particular case, those provisions must be made public.