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There has, justifiably, been much debate about the implications of the judgments of the Supreme Court of the United Kingdom in R (Jackson) v Attorney General  UKHL 56,  AC 262 and AXA General Insurance Ltd v The Scottish Ministers  UKSC 46,  3 WLR 871. What is perhaps the most constitutionally significant aspect of these judgments is the court’s professed residual power to review legislation on common law grounds. The term ‘residual power’ is the coinage used by Lord Reed in a seminar conducted at Balliol College, Oxford, on May 2, 2012. The very labelling of the power as residual is significant because it evokes questions about the source of the power and the frequency with which it be deployed. The label ‘residual’ suggests that the power is not to be located in the text of a statute. This is rather basic, but is of course, one source of controversy surrounding the very assertion of this residual power. The fact that it is not located in a statutory text raises questions as to the democratic legitimacy of the power; it also heightens concerns about the scope of such a power and about the wisdom of permitting judges to delineate the scope of that power. Beyond the question of legitimacy lie further questions about the implications of the judgments in Jackson and AXA with respect to the definition and application of the purported residual power to review legislation. I will first distinguish the residual powers asserted by judges in the two cases, discuss whether the vagueness of the residual powers poses a problem, and end with a note on the precedential impact of the judgments.
1. The Purported Residual Powers of the Court
Two residual categories have been identified by the Law Lords in these two cases. The first of these is ‘exceptional circumstances review’ as outlined by Lord Steyn in Jackson and Lord Hope in AXA. This category of review may arise where a statute violates the rule of law and the court is required to invalidate the statute because of its duty to protect the rule of law. The second is where review can be justified on the principle of legality as outlined by Lord Reed in AXA. The latter branch of residual power is potentially more limited than the former in at least two senses. It is conceptually more limited in that, though Lord Reed invokes the rule of law in support of this power, it is based more specifically on the principle of legality. For Lord Reed, then, the court’s residual power to invalidate legislation rests on the presumption of legality, which ‘means not only that Parliament cannot itself override fundamental rights or the rule of law by general or ambiguous words, but also that it cannot confer on another body, by general or ambiguous words, the power to do so.’ This is a restatement of the principle of legality as articulated by Lord Steyn in Reg. v. Secretary of State for the Home Department, Ex parte Pierson  AC 539 and Lords Steyn and Hoffmann in R v Secretary of State for the Home Department, ex p Simms  2 AC 115. Secondly, legality-based power is of more limited scope in its applicability. Insofar as it allows courts to disapply or invalidate legislation, it appears to only be applicable to subordinate legislatures because Lord Reed’s reasoning on the principle of legality is that Parliament cannot, by general or ambiguous words, confer on another body the power to override fundamental rights or the rule of law [152-153]. The principle is therefore quite potent as applied to legislation of a subordinate legislature because it would allow the court to invalidate a statute or statutory provision as outwith the powers of that legislative body. As applied to a sovereign Parliament such as the UK Parliament, the principle allows for (creative) interpretation of Acts of Parliament but not outright judicial rejection of such legislation. By contrast, the power identified by Lord Steyn in Jackson and Lord Hope in AXA has the potential to be much broader, encompassing the potential for review of legislation enacted by the UK Parliament.
2. Vagueness: Problem? What Problem?
Commentators have rightly indicated that the residual categories (particularly ‘exceptional circumstances’ review based on the rule of law) suffer from a vagueness problem. The vagueness arises in at least two areas. The first is the lack of clarity as to what constitutes ‘exceptional circumstances’. This in turn raises questions as to the rule of law values which would have to be threatened and as to degree of threat to such values which would provoke the court’s intervention. The second area of vagueness is that it is unclear what action or intervention such a threat might provoke from the courts. Will the court’s intervention appear in the form of extremely creative (re)interpretation of statute, disapplication of a statute in a particular case or invalidation of a statute? The vagueness inherent in the exceptional circumstances category may be defended on the ground that as a residual power, there must be uncertainty in its formulation. Yet, it is not entirely convincing that a residual category must necessarily be vague. A residual power could be formulated to permit the court’s intervention only in circumstances where legislation seeks to abolish judicial review, thereby interfering with access to the courts. This was one of the examples given by Lord Steyn in Jackson  and it is conceivable that exceptional circumstances review could be limited to exceptional possibility. The problem is that Lord Steyn did not limit the circumstances to such cases nor did he provide a definite indication of the scope of ‘exceptional circumstances’. It is arguable that the judges have quite deliberately left the category vague in order to allow flexibility for the court to develop the category as it sees fit and to craft what it deems to be an appropriate response to circumstances it has not, and perhaps could not have foreseen. Perhaps more importantly, Lord Reed in the seminar at Balliol College, took the view that it was ‘not a problem’ that the content of the ‘rule of law’ and ‘fundamental rights’ which underlie both categories of residual power are vague. In his view, this may encourage authorities to be more careful. This argument in defence of the vagueness of the scope of the residual powers emphasizes the inter-institutional dialogue that is at play in AXA and Jackson.
3. Inter-Institutional Dialogue and Setting Precedents
It has been accurately observed that some of the obiter dicta in Jackson were a direct response to the proposed Asylum and Immigration (Treatment of Claimants etc.) Bill, which would have sought to oust judicial review of decisions of the court, even where those decisions were alleged to be in breach of natural justice. One could therefore be tempted to relegate these judicial pronouncements to the realm of inter-institutional dialogue and as mere warning shots directed at the government and Parliament. This, however, does not mean that we must not take the judges seriously. AXA is proof of the need to take the assertion of residual powers of the court seriously and of the need to debate the practical implications of the purported residual powers of the courts and to interrogate the normative justification for such powers. It is true that the actual judgment in AXA was limited to finding that the Supreme Court had power to review Acts of the Scottish Parliament on the common law grounds identified by the judges, however, this in itself is a significant development which was based, in part, on the dicta in Jackson regarding the power to review Acts of the UK Parliament. Further, Lord Hope’s judgment in AXA, with which the other Law Lords concurred, stated that ‘[t]he question whether the principle of the sovereignty of the United Kingdom Parliament is absolute or may be subject to limitation in exceptional circumstances is still under discussion.’  Out of inter-institutional dialogue, the roots of dramatic precedent may spring up. We should not discount the role of persuasive precedent in developing the law, particularly the ‘uncharted territory’ of constitutional law which arose for discussion in these two cases.
It remains to be seen exactly how these judgments will affect the development of constitutional theory and practice. The issues raised in this piece, and others that have been discussed elsewhere, must be addressed. The judgments are, at least, one step in grappling with the tension that may arise between parliamentary sovereignty and other constitutional principles.
Se-shauna Wheatle is a DPhil Candidate at Balliol College, and Lecturer in Law, Exeter College, University of Oxford.