The question of whether a legitimate expectation has arisen will depend on a number of factors. This is particularly true of substantive legitimate expectation, where the threshold that the claimant must satisfy is especially high. The factors that the Court will consider include:
- whether the promise was clear and unequivocal.
- whether the decision-maker had the power to make the promise (see R v North and East Devon Health Authority ex p Coughlan  QB 123). If not, it is unlikely that a claim for legitimate expectation will succeed, although there are exceptions where human rights are engaged.
- whether the promise was made by a person with sufficient authority to commit the decision-maker to the proposed course of action (R (Bloggs 61) v Secretary of State for the Home Department  EWCA Civ 686).
- whether the person to whom the promise was made acted upon that promise and is in a worse position as a result of those actions (R v Secretary of State for Education and Employment Ex p. Begbie  1 WLR 1115).
Where the Court is satisfied that a legitimate expectation has arisen, it may still allow the decision-maker to go back on its word (i.e. to defeat the legitimate expectation) where there is an overriding public interest in allowing the public authority to do so.