This was a case involving illegal immigrants who claimed LE based on representations etc. Facts are unimportant. Crucial is Laws LJ’s approach (with which the other two Lord Justices agreed).
Laws LJ (NB these comments are obiter): He wants ‘proportionality’ to become a separate head of public law challenge. ‘A public body's promise or practice as to future conduct may only be denied, and thus the standard I have expressed may only be departed from, in circumstances where to do so is the public body's legal duty, or is otherwise, to use a now familiar vocabulary, a proportionate response (of which the court is the judge, or the last judge) having regard to a legitimate aim pursued by the
public body in the public interest. The principle that good administration
requires public authorities to be held to their promises would be undermined
if the law did not insist that any failure or refusal to comply is objectively
justified as a proportionate measure in the circumstances.’ He used this because “abuse of power”, as the court asserted as the basis for upholding substantive LE in category 3 in Coughlan, is not itself a standard of review. He went on to say that “Proportionality will be judged, as it is generally to be judged, by the respective force of the competing interests arising in this case. Thus where the representation relied on amounts to an unambiguous promise; where there is detrimental reliance, where the promise is made to an individual or a specific group; these are instances where denial of the expectation is likely to be harder to justify as a proportionate factor…This approach makes no distinction between procedural and substantive expectations. Nor should it. The dichotomy between procedure and substance has nothing to say about the reach of the duty of good administration.”
This is a much better, clearer approach. Proportionality is a clearer standard of review than that set out in Coughlan and avoids the problems of categorisation. Also it refuses to engage in the strange distinctions between procedural and substantive LE.