Introduction
The constitution of the United Kingdom is often described as being built upon two fundamental pillars: parliamentary sovereignty and the rule of law. Parliamentary sovereignty, in its traditional sense, posits that Parliament has the ultimate and unlimited power to create or repeal any law. The rule of law, by contrast, insists that all, including the government itself, are subject to the law and that law should possess certain qualities, such as clarity, predictability, and fairness. The question of whether the rule of law is subordinate to parliamentary sovereignty addresses the very heart of the UK's constitutional arrangements. This essay will argue that while the orthodox constitutional position holds that the rule of law is indeed subordinate to the supreme power of Parliament, this view has been significantly challenged by modern judicial thinking. The relationship is now better understood as a complex and tense partnership, but one in which parliamentary sovereignty, for now, retains its ultimate legal primacy.
The Orthodox View: Parliamentary Sovereignty as the Ultimate Principle
The traditional doctrine of parliamentary sovereignty was most famously articulated by A.V. Dicey, who defined it with three key features: Parliament has the power to make or unmake any law whatsoever; no person or body is recognised by the law of England as having a right to override or set aside the legislation of Parliament; and the right or power of Parliament extends to every person and matter within the territory (Dicey, 1959). This 'continuing' sovereignty means that no Parliament can bind its successors.
Under this orthodox model, the rule of law is a principle of political morality that may guide and influence Parliament but cannot legally constrain it. If Parliament were to pass an Act that was retrospective in effect, targeted specific individuals, or removed access to the courts, the judiciary would be constitutionally bound to apply it. The courts’ role is to interpret and apply the will of Parliament as expressed in statute, not to question the validity of that statute based on principles like justice or fairness. The classic judicial expression of this deference can be seen in British Railways Board v Pickin [1974] AC 765. In this case, the House of Lords refused to investigate allegations that a private Act of Parliament had been passed based on a misleading preamble, affirming the 'enrolled bill rule' which states that once an Act is on the statute book, the courts cannot question its validity or the process by which it was made. Lord Reid stated that the courts have no power to disregard an Act of Parliament, "whether it be public or private, nor even to examine proceedings in Parliament in order to determine whether the passing of an Act was obtained by irregularity or fraud". This case clearly demonstrates the subordination of judicial inquiry, a key component of the rule of law, to the absolute authority of a statute passed by Parliament.
The Challenge from the Rule of Law
In recent decades, this orthodox view has been subject to increasing scrutiny and challenge, primarily from the judiciary. This challenge has been fuelled by a shift towards a more ‘substantive’ conception of the rule of law, which goes beyond mere formal legality. A formal or ‘thin’ view of the rule of law requires only that laws are properly enacted and that government acts according to law. In contrast, a ‘substantive’ or ‘thick’ view, as championed by theorists like T.R.S. Allan and exemplified in the work of Lord Bingham, argues that the rule of law also requires the law to protect fundamental human rights (Allan, 2003; Bingham, 2010). If the rule of law has this substantive content, it creates a potential conflict with a Parliament that could, in theory, legislate to abolish such rights.
Judges have developed interpretive principles that give practical effect to this more robust view of the rule of law. A key tool is the principle of legality, articulated by Lord Hoffmann in R v Secretary of State for the Home Department, ex parte Simms [2000] 2 AC 115. He stated that "fundamental rights cannot be overridden by general or ambiguous words" and that in the absence of express language or necessary implication to the contrary, "the courts therefore presume that even the most general words were intended to be subject to the basic rights of the individual". This principle does not deny parliamentary sovereignty; it presumes that Parliament does not intend to legislate contrary to fundamental rights and requires Parliament to be explicit if it wishes to do so. While it preserves Parliament's ultimate power, it places a significant political and procedural hurdle in the way of infringing the rule of law, forcing Parliament to confront the consequences of its actions directly.
The most direct judicial challenge to the absolute supremacy of Parliament came in the case of R (Jackson) v Attorney General [2005] UKHL 56. While the case was concerned with the legality of the Parliament Act 1949, several of the Law Lords made powerful obiter dicta comments on the relationship between parliamentary sovereignty and the rule of law. Lord Steyn suggested that the traditional Diceyan view of absolute sovereignty was "out of place in the modern United Kingdom" and that "in exceptional circumstances involving an attempt to abolish judicial review or the ordinary role of the courts, the… Supreme Court may have to consider whether this is a constitutional fundamental which even a sovereign Parliament acting at the behest of a complaisant House of Commons cannot abolish". Even more forcefully, Lord Hope declared that "parliamentary sovereignty is no longer, if it ever was, absolute… The rule of law enforced by the courts is the ultimate controlling factor on which our constitution is based". These statements suggest a radical possibility: that the courts might, in an extreme case, refuse to apply an Act of Parliament that fundamentally undermines the rule of law, thereby asserting that the rule of law is not subordinate, but is in fact a more fundamental principle than parliamentary sovereignty itself.
A Contested Relationship in Practice
Despite the powerful rhetoric in Jackson, the constitutional reality remains that no UK court has ever struck down a piece of primary legislation on the grounds that it violates the rule of law. The judicial position remains one of exercising restraint and relying on powerful interpretive strategies rather than direct confrontation. The Human Rights Act 1998 (HRA) is a prime example of this balanced approach. The HRA incorporates the European Convention on Human Rights into domestic law and, under section 3, requires courts to read and give effect to primary legislation in a way that is compatible with Convention rights "so far as it is possible to do so". This has led to some radical interpretations of statutes, as seen in Ghaidan v Godin-Mendoza [2004] UKHL 30. However, the HRA was carefully drafted to preserve parliamentary sovereignty. Where a compatible interpretation is not possible, the higher courts may issue a 'declaration of incompatibility' under section 4. Such a declaration has no legal effect on the validity of the statute; it is a signal to Parliament, which may then choose to amend the law (or not). The long-running political and legal saga over prisoner voting, following the decision in Hirst v United Kingdom (No 2) (2005) 42 EHRR 41, demonstrates that Parliament can and does resist pressure to change laws even when they are found to be incompatible with rights principles, reinforcing its ultimate legislative authority.
Therefore, the modern relationship appears to be a political dialogue rather than a fixed hierarchy. The courts use the rule of law as a standard to interpret legislation and hold the executive to account, as seen in cases like Anisminic Ltd v Foreign Compensation Commission [1969] 2 AC 147, where the House of Lords interpreted an ouster clause narrowly to protect access to the courts. The judiciary signals its commitment to fundamental principles, warning Parliament of the constitutional dangers of overstepping. However, the 'nuclear option' contemplated in Jackson remains untested. The courts continue to operate on the assumption that Parliament is the senior partner in the constitutional relationship, even if they are more willing than ever to question its instructions.
Conclusion
In conclusion, the question of whether the rule of law is subordinate to parliamentary sovereignty does not have a simple answer. The orthodox Diceyan doctrine, supported by cases like Pickin, clearly places parliamentary sovereignty as the supreme legal fact of the constitution, making the rule of law legally subordinate. However, this view no longer reflects the complexity of the modern constitution. Through the development of the principle of legality and the powerful judicial warnings issued in Jackson, the judiciary has asserted a more co-equal role for the rule of law, arguing it is a fundamental principle that may even limit the power of Parliament.
Nevertheless, in practice, this challenge has not yet translated into a reversal of the hierarchy. The structure of the Human Rights Act 1998 and the absence of any case where a court has invalidated an Act of Parliament confirm that legal sovereignty still resides with Parliament. The relationship is now best seen not as one of simple subordination, but as one of constitutional tension and dialogue. The rule of law acts as a powerful interpretive presumption and a significant political constraint on Parliament. But until a court takes the final, revolutionary step of refusing to apply an unambiguous statute, the legal position remains that the rule of law, while fundamental, is ultimately subordinate to a sovereign Parliament.
References
Allan, T.R.S. (2003) Constitutional Justice: A Liberal Theory of the Rule of Law. Oxford University Press.
Bingham, T. (2010) The Rule of Law. Allen Lane.
Dicey, A.V. (1959) An Introduction to the Study of the Law of the Constitution. 10th edn. Macmillan.
Anisminic Ltd v Foreign Compensation Commission [1969] 2 AC 147.
British Railways Board v Pickin [1974] AC 765.
Ghaidan v Godin-Mendoza [2004] UKHL 30.
Hirst v United Kingdom (No 2) (2005) 42 EHRR 41.
Human Rights Act 1998.
R (Jackson) v Attorney General [2005] UKHL 56.
R v Secretary of State for the Home Department, ex parte Simms [2000] 2 AC 115.
