The Stakes of the Unwritten Constitutional Norms and Principles Debate in the UK

In the UK’s ‘uncodified’ constitution, there is little debate about the existence and importance of unwritten constitutional norms and principles. However, there is deep contestation over the content of, and relationship between, these principles, as well as the role they can legitimately play in a democratic constitutional order. For instance, while there is wide acceptance that the principles of parliamentary sovereignty (or supremacy) and the rule of law underpin the UK’s constitution, questions arise about their meaning(s) and relative normative weight. Further questions arise about the descriptive accuracy or normative purchase of ascendant/less well-established principles such as the separation of powers, as well as the sharpness of any distinction between political norms – like conventions – and legal principles enforceable by courts.

Unwritten principles serve several important purposes in the UK’s constitution. For example, they provide guardrails for judicial interpretation of legislation, and they form or give rise to substantive rules about the limits of legislative, judicial and executive power. Many of these rules and norms are represented in written form, but they are distinguished from written norms because their legitimacy and scope are not derived from the text(s) in which they appear.

With a growing body of research in this area, it is worth considering why these issues matter, and what is at stake. This post considers two issues which it argues can only be properly understood once regard is paid to the unwritten principles and norms in the UK’s constitution: the limits of Westminster’s legislative power, and the nature of the UK’s territorial constitution. In so doing, it demonstrates that unwritten constitutional norms and principles illuminate the relationship between written and unwritten constitutionalism, and between legal and political norms.

Determining The Limits of Legislative Power

The vexed issue of the limits – if any – of Westminster’s legislative power can only be understood by reference to unwritten constitutional norms and principles. Although parliamentary sovereignty’s continuing importance within the UK’s constitution has been frequently affirmed by the Supreme Court, the scope and meaning of that principle, as well as its interaction with other constitutional principles, remains hotly contested. Recent case law, especially emerging from the UK’s departure from the EU, has highlighted disputes over whether more formal conceptions of parliamentary supremacy compare preferably with functional or facilitative understandings of the principle. While the formal understanding secures the validity of legislation once it is enacted, the facilitative understanding addresses – and protects – the conditions under which Westminster’s parliamentary powers are exercised. As such, the latter understanding can be, and has been, used to restrain government action that undermines the conditions that enable Parliament to perform its constitutional functions. For example, in 2019, Parliament, poised to extend the period of negotiations between the EU and the UK on the terms of its withdrawal, was prorogued for five weeks on the advice of the then Prime Minister Boris Johnson. Following a legal challenge, the Supreme Court ruled in Miller, Cherry (2019) that this prorogation was unlawful because it violated the constitutional principles of parliamentary sovereignty and parliamentary accountability.

This more substantive conception of parliamentary sovereignty, however, has been criticized as an unorthodox expansion of the principle without foundation in precedent. Moreover, in a critique that highlights the unsettled boundaries between the legal and political constitution, the court’s reliance on the norm of ministerial accountability to parliament has been described as the conversion of  a constitutional convention – a political norm – into a legal principle (Finnis, 2019). Accordingly, the sharpness of the distinction between political norms and their legal counterparts, and whether they rest on shared constitutional foundations, is also a point of disagreement in the literature.

The sovereignty principle therefore appears to facilitate a broad and strongly normative reading of Westminster’s legislative power. However, traditionally, it is the other of the ‘twin pillars’ of the constitution – the rule of law – that might serve to counterbalance the breadth of Westminster’s legislative power. However, this is a principle whose meaning and breadth are also deeply contested, including familiar longstanding contestation over whether to adopt thinner (formal) conceptions or thicker (substantive) conceptions of the rule of law.

The rule of law principle serves a variety of purposes in the context of Westminster’s legislative power. First, rather than the rule of law being necessarily antithetical to parliamentary sovereignty, it serves to apply fundamental constitutional values to legislation, particularly through the principle of legality (ex p Pierson (2015)). This interpretive principle requires that legislation be given meaning through the lens provided by the rule of law. This means that a reading of legislation that is inconsistent with the rule of law, fundamental rights or principles will only be possible if express, clear words are used.  Accordingly, the effect of statutes that purport to limit judicial review of government decisions – a key vehicle through which the rule of law is operationalized – can be curtailed through judicial interpretation (Privacy International (2019)).

The principle of legality thereby protects fundamental rights and principles from incidental (or accidental) incursion, while maintaining parliamentary sovereignty by formally allowing Parliament to override those rights and norms if it expresses its intention to do so with sufficient clarity. However, though this formulation appears to reconcile parliamentary sovereignty with the rule of law, its application in some cases has prompted critics of strong judicial power to argue that these kinds of judicial decisions encroach upon Parliament’s legislative power, and inappropriately convert political questions into legal ones (Ekins and Gee, 2017).  The scope and normative force of unwritten principles clearly overlaps with – and profoundly impacts – debates about the role and power of the courts, and their interaction with the political actors.

Second, as vividly revealed in commentary and dicta in the UK’s highest courts which countenance substantive restrictions upon Parliament’s supremacy, the rule of law may also play a role in determining the limits of Westminster’s legislative power. Such an extraordinary judicial response is posited as a reaction to hypothetical exceptional circumstances in which Parliament seeks to ‘subvert’ a core rule of law requirement by abolishing judicial review, or severely undermining the rule of law by excluding an area of the law from judicial review. Despite the orthodox view that parliamentary supremacy means that courts cannot invalidate Acts of Parliament and certainly cannot do so by appeal to constitutional principles, in Jackson v AG (2005) and AXA v Lord Advocate (2011), several judges suggested that in extreme circumstances, judges may prevent Parliament from subverting principles such as the rule of law. Most recently in the 2019 Privacy International decision Lord Carnwath (with whom two other judges agreed) provocatively stated:

I see a strong case for holding that, consistently with the rule of law, binding effect cannot be given to a clause which purports wholly to exclude the supervisory jurisdiction of the High Court to review a decision of an inferior court or tribunal, whether for excess or abuse of jurisdiction, or error of law. In all cases, regardless of the words used, it should remain ultimately a matter for the court to determine the extent to which such a clause should be upheld, …and to determine the level of scrutiny required by the rule of law. [144]

Recent cases in the High Court and Court of Appeal have indicated that reasoning of this kind is only likely to be engaged when, in a courts’ view, a piece of legislation represents a particularly egregious, and irreconcilable, infringement of the rule of law. A question dominating current discourse is whether the UK Government’s attempts to remove asylum seekers to Rwanda meet that threshold. The Supreme Court found the government’s policy unlawful on the ground that asylum seekers sent to Rwanda faced a real risk of refoulement and that, consequently, Rwanda was not a safe country.  The Government’s retort in the form of the Safety of Rwanda Bill, seeks to effectively overturn the effect of the UKSC decision. The critique of the Bill, in both the legislature and the academic commentary, has been firmly and expressly rooted in the Bill’s implications for unwritten constitutional principles, primarily the rule of law and separation of powers. The Bill challenges the rule of law firstly by requiring courts to treat Rwanda as a safe country and barring courts from reviewing or appealing decisions to remove a person to Rwanda on grounds that Rwanda is not a safe country and, secondly, by authorising a breach of the UK’s international legal obligations. The Bill brings to a head simmering debates over the the extent to which Westminster’s sovereignty allows it to legislate freely, the capacity of unwritten principles (and which ones) to condition that power, and the locus of institutional authority to enforce these principles.

The full scope and limits of Westminster’s legislative power can only be accurately recognised when unwritten norms and principles are properly acknowledged. Even where these principles are reflected in writing, such as legislative references to the rule of law and parliamentary sovereignty, these texts cannot exhaustively define, provide for the interaction between, or method of enforcement for, such abstract fundamental constitutional principles. Only unwritten constitutional norms and principles can supply those intertextual connections and inform how these norms fit within the constitutional landscape.

The Territorial Constitution

In the UK, significant legislative power can be exercised not only by Westminster, but also by legislatures in Wales, Scotland and Northern Ireland as part of the UK’s devolution framework. Much of this framework is the product of legislation, but not all; some important parts of the system are only partially codified or are the products of practice. The dynamics of devolution demonstrates that it is not possible, and certainly not unproblematic, to treat the codified components of the constitution as exhaustive or wholly insulated from the unwritten elements of the constitution and the assumptions that underpin it.

For example, some of the limits on devolved legislative power are implied into the framework by the courts (through the vehicle of the principle of legality), rather than being expressly provided by its texts. Further, some statutory provisions only partially reflect deeper constitutional norms and principles. Section 28(8) of the Scotland Act 1998 is an illustrative example – it provides that ‘the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the consent of the Scottish Parliament’. The majority in Miller I noted that this amounted to ‘legislative recognition of [a] convention’, which was also ‘embodied’ in other texts, and which emerged to protect the legislative competence of the devolved legislatures. However, the Court also recognized that the devolved institutions had, in practice, interpreted that convention in wider terms than reflected in section 28, passing consent motions not only when the UK Parliament intended to legislate in devolved areas, but also when it sought to amend devolved lawmaking powers. However, despite this, the Court was not prepared to accept that the convention had wider constitutional potency than the provision itself recognised and to which the Court could give any meaningful effect, even short of enforcement. This narrow approach arguably fails to recognise that practice and institutional behaviour are important determinants of the meaning and purchase of conventions such as this one, whose normative source (and force) are the product of political consensus.

It has been argued that the Court’s narrow interpretation of s 28(8) may have undermined the ‘constitutional security’ of the devolved nations, and weakened the convention the provision purports to reflect. However, the Supreme Court’s recent jurisprudence on devolution has kept to this narrow approach, with similar results. In the Allister case, for example, the Supreme Court was faced with the interaction between the EU (Withdrawal) Act 2018 and existing legislation governing the territorial constitution. Although, pursuant to the constitutional statutes doctrine, the language required for one statute to override parts of another has been held to turn, to some extent, on the constitutional norms embodied by either, the Court here considered that this kind of analysis had been rendered ‘academic’, adopting instead a ‘mechanical’ approach which considered that the meaning of, and interaction between, the relevant texts could be determined without reference to the normative weight, or constitutional character, of those texts. This approach does not adequately recognise that even those parts of the constitution­­­­­ – like devolution – that are largely products of legislation can nonetheless reflect deeper principles which, if the constitutional order is to possess meaningful normative richness, require recognition in judicial interpretation.

Conclusion: Legitimacy and Constitutional Democracy

In the UK’s uncodified constitution, the prominence of unwritten constitutional norms and principles can easily be asserted. Indeed, it is neither accurate nor useful to consider statutory provisions – or other texts – as exhaustive accounts of the UK’s constitutional rules, principles and norms. However, as these principles are put to more substantive purposes, in cases like Miller II and Privacy International, questions arise about the legitimacy of courts relying on norms which do not find meaningful expression in democratically endorsed sources of the constitution. It might be for this reason that the courts have arguably recently taken a ‘mechanical’, ‘deferential’ turn. However, doing so risks hollowing out a constitutional order in which unwritten norms clearly play an important role, even if there are debates about their substance and relationships.