Substantive legitimate expectation and whether detrimental reliance is required (Re Finucane)

In Re Finucane's Application [2019] UKSC 7, Lord Kerr reviewed the authorities, including R v North and East Devon Health Authority, ex p Coughlan, which recognised that a lawful promise may induce a legitimate expectation of a substantive benefit, so that frustrating it may be so unfair as to amount to an abuse of power. Lord Kerr deduced that where a clear and unambiguous undertaking has been given, the authority will not be allowed to depart from it unless it is shown to be fair to do so, with the court as the arbiter of fairness. Whether the change frustrates reliance is relevant to fairness, but detriment is not a prerequisite of a substantive legitimate expectation claim. The claimant must prove a promise that was clear, unambiguous and devoid of relevant qualification. Here the council's unqualified letter to a small, identified group meets that test, and the weak justification makes a successful claim realistic.

Why A is wrong: Lord Kerr held that detriment is not a prerequisite of a substantive legitimate expectation claim, though reliance bears on fairness.

Why B is wrong: Coughlan and Finucane recognise that a promise may found a substantive, not merely procedural, legitimate expectation.

Why C is wrong: An authority may depart from a promise where the court considers it fair to do so, for example because of an overriding public interest.

Why E is wrong: For a substantive expectation the court judges fairness for itself; it is not confined to Wednesbury irrationality review.