In the matter of an application by Geraldine Finucane for Judicial Review (Northern Ireland) (2019) UKSC 7 considers substantive legitimate expectation from paragraph 55. Lord Kerr on behalf of the Supreme Court concluded:-
“62. From these authorities it can be deduced that where a clear and unambiguous undertaking has been made, the authority giving the undertaking will not be allowed to depart from it unless it is shown that it is fair to do so. The court is the arbiter of fairness in this context. And a matter sounding on the question of fairness is whether the alteration in policy frustrates any reliance which the person or group has placed on it. This is quite different, in my opinion, from saying that it is a prerequisite of a substantive legitimate expectation claim that the person relying on it must show that he or she has suffered a detriment.”
“64. The onus of establishing that a sufficiently clear and unambiguous promise or undertaking, sufficient to give rise to a legitimate expectation, is cast on the party claiming it …”
“70. … it is unnecessary for me in this case to decide whether it is a requirement that there be a reciprocal undertaking by the person or group to whom the promise is made or that they should suffer a detriment in order to sustain a claim for substantive legitimate expectation. But, if it had been necessary to decide that point, I would have concluded that it was not.”
“72. I would disagree with any suggestion that it must be shown that the applicant suffered a detriment before maintaining a claim for frustration of legitimate expectation for a fundamental reason. A recurring theme of many of the judgments in this field is that the substantive legitimate expectation principle is underpinned by the requirements of good administration. It cannot conduce to good standards of administration to permit public authorities to resile at whim from undertakings which they give simply because the person or group to whom such promises were made are unable to demonstrate a tangible disadvantage. Since the matter does not arise, however, it is better that the point be addressed in a future case when it is truly in issue.”
“76. Where political issues overtake a promise or undertaking given by government, and where contemporary considerations impel a different course, provided a bona fide decision is taken on genuine policy grounds not to adhere to the original undertaking, it will be difficult for a person who holds a legitimate expectation to enforce compliance with it.”
Lord Carnwath added observations at paragraphs 156-160.