Salvesen v Riddell  UKSC 22 is interesting and significant for all sorts of reasons, not least because the UK Supreme Court ruled part of an Act of the Scottish Parliament to be unlawful—that is, outside Holyrood’s competence—on the ground that it conflicted with the European Convention on Human Rights. The facts of the case and the legal issues raised by it are well summarized in the press release that accompanied the judgment, and I will not repeat them here.
However, the most interesting aspect of the case (to me) is what may at first appear to be an obscure remedial point – but which in fact raises some quite fundamental questions. Having decided that the relevant provision of the Act was incompatible with the ECHR, the Court went on to suspend the effect of its judgment, in order to allow time for the legislation to be amended. In doing so, it relied upon s 102 of the Scotland Act 1998, which says:
(1) This section applies where any court or tribunal decides that—
(a) an Act of the Scottish Parliament or any provision of such an Act is not within the legislative competence of the Parliament, or
(b) a member of the Scottish Executive does not have the power to make, confirm or approve a provision of subordinate legislation that he has purported to make, confirm or approve.
(2) The court or tribunal may make an order—
(a) removing or limiting any retrospective effect of the decision, or
(b) suspending the effect of the decision for any period and on any conditions to allow the defect to be corrected.
There are, of course, good practical reasons why this may be necessary. But a question arises about the relationship between a particular provision such as s 102 and the general theory of invalidity in public law. The normal principle, affirmed very clearly by a majority of the Supreme Court in Ahmed v HM Treasury (No 2)  UKSC 5, is that secondary legislation which is ultra vires is without legal effect. The majority therefore refused to suspend a quashing order in respect of such legislation because, as Lord Phillips put it:
The effect of suspending the operation of the order of the court would be, or might be, to give the … impression … that, during the period of suspension of the quashing orders, the provisions to be quashed would remain in force … This court should not lend itself to a procedure that is designed to obfuscate the effect of its judgment.
In other words, quashing unlawful measures merely demonstrates—but does not procure—their invalidity. They are invalid because they are unlawful, not because they have been quashed. The obvious question is: why does this not apply with equal force to ultra vires legislation enacted by the Scottish Parliament? The fact that that Parliament enacts “primary” legislation is neither here nor there: like a UK minister enacting subordinate legislation, the Scottish Parliament has limited authority that is circumscribed by an empowering enactment (viz the Scotland Act 1998). A possible answer is that s 102 implicitly displaces the normal constitutional principle whereby unlawful acts are void whether or not quashed, making the suspension of the court’s decision relevant in Salvesen in a way that it could not have been in Ahmed (No 2).
Another explanation, however, may be found in the fact that Lord Hope, who gave the leading judgment in Salvesen, dissented in Ahmed (No 2), arguing that the risk of obfuscation identified by Lord Phillips, writing for the majority, should not be considered decisive. Instead, Lord Hope was in favour of balancing the advantages and disadvantages (including obfuscation) of suspending the quashing order, and concluded in Ahmed (No 2) that the former outweighed the latter.
But a difficulty nevertheless remains. Lord Hope says in Salvesen that he is “suspend[ing] the effect of the decision that [the relevant provision] is not law”. This, though, merely begs the question: what is the effect of that decision? If its effect is merely clarificatory, then suspending it changes not the legal position but merely its presentation. And this, in turn, raises questions about what would happen if a party refused to proceed on the basis that the unlawful measure was still to be treated as being in force. Could, for instance, another court, in a subsequent case, properly apply a law that had been found to be unlawful by the Supreme Court – even if the latter had “suspended” the “effect” of its decision so holding? It is a shame that the Supreme Court failed to address this fundamental point, which goes to the legal status of unlawful legislation and to the underlying theory of invalidity in public law.