Imagine that a prerogative Order in Council is enacted and that it's incompatible with an ECHR right that covers the same ground as a common law constitutional right. The quotations beneath affirm that the Order in Council can't be quashed on the basis of its incompatibility with the Convention right—but could it be quashed on the ground of its incompatibility with the common law constitutional right?
My question is above. The following is optional to read.
Three further points should be noted regarding the distinction between primary and subordinate legislation.
First, the HRA adopts, in one particularly significant respect, an unusually broad definition of primary legislation. Section 21(1) states that, for the purposes of the HRA, Orders in Council enacted under the royal prerogative are to be treated as primary, not subordinate, legislation. 85 The practical effect of this is that such prerogative legislation cannot be quashed if found incompatible with Convention rights. It can, however, like an Act of Parliament, be the subject of a declaration of incompatibility under s 4.
Categorising prerogative Orders in Council as primary legislation for HRA purposes is anomalous.86 For present purposes, it is unnecessary to get bogged down in the semantics of ‘primary’ and ‘subordinate’ legislation.87 The key point is that the general constitutional position of prerogative Orders in Council is inconsistent with that which they occupy in relation to the HRA. Orders in Council are not the constitutional equals of Acts of Parliament: the former, unlike the latter, can usually be quashed if they are unlawful. The normal principles of judicial review therefore apply: if, for example, a prerogative Order in Council is unreasonable, or made for an improper purpose, or adopted in breach of a legitimate expectation, it can be set aside by the courts. Any doubt that may have existed on this point was put to rest by the House of Lords in Bancoult (No 2).88
This position is entirely correct in principle. In constitutional theory, prerogative Orders in Council are acts of the Crown alone (meaning the executive), not of the Crown-in-Parliament. Orders in Council are therefore not cloaked by the doctrine of parliamentary sovereignty. Also, in constitutional practice, the prerogative is merely a tool in the hands of the executive. There is therefore no good reason why its exercise should be immune from judicial review—and every reason why it should be. Against this background, it is highly dubious that while the courts can quash prerogative Orders in Council if they fall foul of the normal principles of judicial review, they cannot do so if they contravene the Convention rights.
85 See further Chapter 5, section 4.3.
86 Pontin and Billings, ‘Prerogative Powers and the Human Rights Act: Elevating the Status of Orders in Council’  PL 21.
87 See generally McHarg, ‘What is Delegated Legislation?’  PL 539.
88 R (Bancoult) v Secretary of State for Foreign and Commonwealth Affairs (No 2)  UKHL 61,  1 AC 453.
Mark Elliott, Public Law 2020 4 edn, p 790.