CODIFYING THE UK CONSTITUTION: WOULD IT IMPROVE THE EXISTING CONSTITUTIONAL FRAMEWORK?

Introduction

The UK constitution has traditionally remained uncodified existing across a range of political and legal sources rather than within a single authoritative text.[1] Codification is often defended on the grounds that it would enhance clarity strengthen the protection of individual rights and impose firmer legal limits on public power.[2] However critics argue that it would undermine parliamentary sovereignty, reduce constitutional flexibility and expand the role of the judiciary at the expense of democratic decision-making.[3] This article critically assesses whether codifying the UK constitution would represent an improvement on the existing framework. It argues that although codification offers benefits, including legal certainty and constitutional constraint these advantages are outweighed by the costs of reallocating constitutional authority away from Parliament towards the courts. The article will first examine the arguments in favour of codification before assessing the objections and critically evaluating whether the benefits justify such a constitutional transformation.

Arguments in Favour of Codification

Constitutional Clarity and Accessibility

A central argument in favour of codifying the UK constitution is that it would enhance clarity and accessibility. At present the UK’s constitutional rules are dispersed across a range of sources including statutes such as the Parliament Acts, judicial decisions, constitutional conventions and political practices.[4] This dispersion reflects a degree of flexibility but it can also make constitutional rules difficult to identify and understand with certainty[5]. While flexibility is often defended as a strength the accessibility of principles remains important to the rule of law because citizens should be able to understand the legal framework governing the exercise of public power.[6] As Dicey acknowledged the rule of law is associated with certainty and predictability; an uncodified constitution may risk falling of this ideal by making fundamental constitutional rules more difficult to identify. Codification by contrast would consolidate principles into a single authoritative text improving transparency and enabling citizens to better understand the framework within which they are governed. As Stanton and Prescott note accessibility is central to the rule of law echoing Lord Bingham’s emphasis on intelligibility.[7] However accessibility alone does not necessarily produce democratic participation. A constitution may be easier to locate without becoming more meaningful or understandable to the public. The argument for codification is therefore strongest where clarity is combined with mechanisms for accountability and enforcement.

Legal Certainty and Limits on Executive Power

Closely linked to this is the argument that codification would promote certainty and impose clearer limits on the exercise of public power. Codified constitutions typically define the scope of authority and the boundaries of institutional competence with greater precision. In the UK by contrast constitutional limits may derive from legislation, common law principles, conventions and the exercise of judgment.[8] This can generate uncertainty during periods of political conflict. The events surrounding Brexit illustrate the significance of these issues. In R (Miller) v Prime Minister (No 2) the Supreme Court considered whether the Prime Minister’s advice to prorogue Parliament was lawful. Concluded that the advice was unlawful because it frustrated or prevented Parliament from carrying out its constitutional functions without reasonable justification.[9] The case therefore demonstrates that an uncodified constitution does not leave power entirely unconstrained; rather courts may develop and enforce constitutional principles through the common law.[10]

Protection of Fundamental Rights

A further argument in favour of codification concerns the protection of fundamental rights. In codified constitutional systems, fundamental rights may be entrenched and protected through higher-law mechanisms.[11] In the UK rights protection depends significantly upon legislation, including the Human Rights Act 1998 together with common law principles and political accountability.[12] Although the Human Rights Act has significantly strengthened rights protection Parliament retains the ability to amend or repeal legislation under the orthodox doctrine of parliamentary sovereignty.[13] Codification could therefore provide protection against temporary or politically popular majorities by making certain rights more difficult to remove or restrict. This could be particularly valuable where fundamental rights are placed under pressure during periods of social instability.[14]

However stronger rights protection would also raise a constitutional question: who should have the final authority when individual rights conflict with competing political, economic or social interests? Entrenchment may protect rights effectively but only by accepting a greater role for judges in determining the meaning and limits of those rights. The apparent advantage of codification therefore carries the institutional consequence that underpins the wider objection to it: greater legal protection may require a corresponding transfer of constitutional authority from elected institutions towards the judiciary.[15] These advantages are therefore not uncontested. Must be assessed against the distinctive features of the UK’s political constitution.

Arguments Against Codification

Parliamentary Sovereignty

The most powerful objection to codifying the UK constitution concerns its incompatibility with the principle of parliamentary sovereignty, which has long been regarded as the cornerstone of the UK’s constitutional order.[16] Under Dicey’s orthodox account Parliament possesses the authority to ‘make or unmake any law whatever’ with no legal limits on its legislative competence.[17] Codification would not necessarily produce a model of constitutional supremacy but a genuinely entrenched constitution would require constitutional rules to have a status different from ordinary legislation.[18] Depending on its design this could permit courts to invalidate legislation, issue declarations of incompatibility or require Parliament to follow special procedures before altering constitutional provisions.[19] Any of these approaches could represent a departure from the traditional understanding of parliamentary sovereignty.

The constitutional issue is therefore not simply whether the constitution should be written down but whether some constitutional rules should be legally superior to Acts of Parliament. In either case codification would represent a departure from Diceyan sovereignty and weaken the democratic supremacy of Parliament as the primary law-making body. This concern has been reinforced by the courts themselves. In R (Miller) v Secretary of State for Exiting the European Union the Supreme Court reaffirmed that parliamentary sovereignty remains the principle of the UK constitution even in the context of EU membership and its aftermath.[20] The decision therefore demonstrated the importance of Parliament in authorising constitutional change rather than establishing that courts themselves possess general authority to determine constitutional policy.

Codification would alter this balance by entrenching principles against ordinary legislative change. Critics therefore argue that it could replace a constitution, in which constitutional disputes are substantially resolved through Parliament and political accountability with a more legal constitution in which courts have greater responsibility for determining constitutional boundaries.

Constitutional Flexibility

A second major objection is that codification would erode the flexibility that characterises the UK constitution.[21] Unlike codified systems the UK constitution has historically evolved incrementally responding pragmatically to social and legal developments through ordinary legislation, conventions and institutional reform.[22] This flexibility has allowed the constitution to adapt to changes, including devolution EU membership and withdrawal and the expansion of rights protection without the need for wholesale constitutional revision. As Wicks observes the historical development of the constitution illustrates its capacity to adapt to changing political circumstances.[23]

This flexibility however comes at the cost of certainty. May allow governments with strong parliamentary majorities to make significant constitutional changes relatively easily. Codification risks replacing this flexibility with rigidity. Written constitutions typically require amendment procedures that make constitutional change slow and politically difficult.[24] Comparative experience, that of the United States demonstrates that rigid amendment procedures can make constitutional reform difficult even where political circumstances have changed substantially.[25]

In the UK context critics argue that rigidity would be especially problematic given the absence of a revolutionary founding moment or settled consensus on constitutional fundamentals. The process of codification would therefore involve choices about which principles should be entrenched and which institutions should possess ultimate authority. Than simply recording existing constitutional rules codification could consequently create new constitutional arrangements. It may therefore provide stability. At the risk of freezing contested political compromises into a framework that future generations may find difficult to alter. Codification could consequently limit the ability of generations to respond democratically to new constitutional challenges.

Judicialisation of Politics

Another concern closely linked to the erosion of sovereignty is the risk that codification would accelerate the judicialisation of politics by expanding the constitutional role of the courts.[26] A codified constitution would require judges to interpret provisions and determine their application to disputes between institutions and individuals. Whether this would include a power to invalidate legislation would depend upon the model adopted. Nevertheless without an explicit strike-down power judges could acquire substantial influence over constitutional meaning.

The risks of judicialisation can be illustrated by R (Miller) v Prime Minister (No 2) where the Supreme Court determined the limits of the prerogative power to prorogue Parliament.[27] The Court’s judgment was grounded in principle and was not simply an attempt to resolve a political disagreement. Nevertheless the case demonstrates how courts may become central to disputes concerning the relationship between Parliament and the executive. Codification could make such judicial involvement more frequent by placing questions within a more extensive framework of legally enforceable rules. This illustrates how codification could normalise resolution of fundamentally political disputes rather than confining such intervention to exceptional circumstances.

Political constitutionalists, notably JAG Griffith argue that codification would entrench judicial supremacy at the expense of democratic decision-making.[28] From this perspective political accountability allows constitutional disagreements to be addressed through elected institutions, public debate and electoral consequences whereas judicialisation may transfer contested questions into a forum where unelected judges possess greater interpretive authority.

This objection does not establish that judicial review is inherently undesirable. Courts already play a role in maintaining legal limits on public power within the uncodified constitution. Rather it demonstrates that codification would alter the balance between political constitutionalism. The question is therefore not whether courts should have any role but how far that role should extend and whether judges should ultimately determine the boundaries of constitutional authority. From this perspective codification threatens to re-orient the UK constitution away, from its political character.

Critical Evaluation

The competing arguments demonstrate that the question of codification cannot be resolved simply by identifying whether a written constitution would be clearer or more accessible. Codification would undoubtedly offer advantages. A single constitutional text could make constitutional rules easier to identify, provide greater certainty concerning institutional powers and potentially strengthen the protection of fundamental rights.[29] These benefits are particularly significant where unclear constitutional arrangements permit uncertainty concerning the limits of executive authority.

However, these advantages must be assessed against the institutional consequences of codification. The principal difficulty is that constitutional clarity and legal entrenchment are not institutionally neutral. Once constitutional rules acquire superior legal status, questions inevitably arise concerning who should interpret those rules and determine their limits. A codified constitution could therefore increase the authority of courts even if judicial supremacy were not its explicit objective. The more detailed and enforceable the constitutional text became, the greater the potential for courts to determine disputes that are currently resolved through political processes.

The UK’s existing constitution also demonstrates that flexibility and political accountability can themselves have constitutional value.[30] Its uncodified character allows constitutional arrangements to develop incrementally and permits Parliament to respond to changing political circumstances without following particularly demanding amendment procedures[31]. This does not mean that the existing framework is free from weaknesses. Its complexity can make constitutional rules difficult to understand, while reliance on political conventions may create uncertainty concerning the limits of governmental power.

The strongest case for reform is therefore not necessarily a case for comprehensive codification. Targeted reforms could improve accessibility, clarify important constitutional principles and strengthen accountability without transferring extensive constitutional authority from Parliament to the judiciary. Such an approach would preserve the flexibility of the existing framework while addressing some of its most significant weaknesses.

Ultimately, codification would represent more than the organisation of existing constitutional rules into a single document. It would involve a fundamental decision about where constitutional authority should lie. The benefits of certainty and rights protection must therefore be weighed against the consequences for parliamentary sovereignty, political accountability and judicial power. On balance, the institutional costs of comprehensive codification outweigh its advantages within the distinctive constitutional context of the UK.

Conclusion

Whether codification would improve the UK constitution depends less on its technical advantages than on how constitutional authority ought to be exercised and controlled. Codification promises greater clarity, legal certainty and stronger protection against abuses of public power, but these benefits come at the potential cost of shifting constitutional authority from Parliament towards the courts.[32] The UK’s constitutional tradition has historically prioritised political accountability and parliamentary control over extensive legal entrenchment, accepting a degree of uncertainty and flexibility as the price of democratic responsiveness.

Codification would therefore not merely rationalise existing arrangements. It would require fundamental choices about which constitutional principles should be entrenched, how easily they should be amended and which institution should have ultimate authority to interpret them. While stronger rights protection and clearer limits on executive power may provide compelling reasons for reform, these objectives could only be achieved through a constitutional settlement that changes the relationship between Parliament and the judiciary.

The uncodified constitution should therefore not be understood simply as an incomplete or outdated model awaiting correction. Its weaknesses in accessibility and certainty are genuine, but they coexist with flexibility and political accountability. Rather than pursuing comprehensive codification, constitutional reform should focus on targeted measures that improve accessibility, clarify constitutional conventions and strengthen accountability without fundamentally displacing parliamentary sovereignty.[33]

Codification is not inherently superior; it represents a fundamentally different vision of constitutional governance. Its desirability ultimately depends on whether the benefits of certainty and rights protection justify transferring a greater share of constitutional decision-making from elected institutions to the judiciary. On balance, the existing uncodified framework, subject to targeted reform, remains preferable to comprehensive codification.

Table of Cases

R (Miller) v Prime Minister (No 2) [2019] UKSC 41

R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5

Table of Legislation

Human Rights Act 1998

Bibliography

Books

Dicey AV, Introduction to the Study of the Law of the Constitution (JWF Allison ed, first published 1885, OUP 2013)

Goldsworthy J, Parliamentary Sovereignty: Contemporary Debates (Cambridge University Press 2010)

Levinson S, Framed: America’s 51st Constitution and the Crisis of Governance (OUP 2012)

Stanton J and Prescott C, Public Law (4th edn, OUP 2025)

Wicks E, The Evolution of a Constitution: Eight Key Moments in British Constitutional History (Hart Publishing 2006)

Journal Articles

Feldman D, ‘Human Rights, Terrorism and Risk: The Roles of Politicians and Judges’ (2006) 1 Public Law 364

Griffith JAG, ‘The Political Constitution’ (1979) 42 Modern Law Review 1

[1] AV Dicey, Introduction to the Study of the Law of the Constitution (JWF Allison ed, first published 1885, OUP 2013).

[2] J Stanton and C Prescott, Public Law (4th edn, OUP 2025) 219-292.

[3] JAG Griffith, ‘The Political Constitution’ (1979) 42 Modern Law Review 1, 19.

[4] AV Dicey, Introduction to the Study of the Law of the Constitution (JWF Allison ed, first published 1885, OUP 2013).

[5] J Stanton and C Prescott, Public Law (4th edn, OUP 2025) 120.

[6] Ibid.

[7] Ibid 222-223.

[8] Ibid.

[9] R (Miller) v Prime Minister (No 2) [2019] UKSC 41.

[10] Ibid.

[11] D Feldman, ‘Human Rights, Terrorism and Risk: The Roles of Politicians and Judges’ (2006) 1 Public Law 364, 372.

[12] Human Rights Act 1998.

[13] AV Dicey, Introduction to the Study of the Law of the Constitution (JWF Allison ed, first published 1885, OUP 2013) 97-114.

[14] D Feldman, ‘Human Rights, Terrorism and Risk: The Roles of Politicians and Judges’ (2006) 1 Public Law 364, 372.

[15] Ibid.

[16] AV Dicey, Introduction to the Study of the Law of the Constitution (JWF Allison ed, first published 1885, OUP 2013).

[17] Ibid 27-28.

[18] J Goldsworthy, Parliamentary Sovereignty: Contemporary Debates (Cambridge University Press 2010) 202-222.

[19] Ibid.

[20] R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5, [43].

[21] E Wicks, The Evolution of a Constitution: Eight Key Moments in British Constitutional History (Hart Publishing 2006) 1.

[22] Ibid 351-355.

[23] Ibid.

[24] S Levinson, Framed: America’s 51st Constitution and the Crisis of Governance (OUP 2012).

[25] Ibid.

[26] JAG Griffith, ‘The Political Constitution’ (1979) 42 Modern Law Review 1, 19.

[27] R (Miller) v Prime Minister (No 2) [2019] UKSC 41.

[28] JAG Griffith, ‘The Political Constitution’ (1979) 42 Modern Law Review 1, 19.

[29] J Stanton and C Prescott, Public Law (4th edn, OUP 2025) 219-292.

[30] E Wicks, The Evolution of a Constitution: Eight Key Moments in British Constitutional History (Hart Publishing 2006).

[31] Ibid.

[32] J Goldsworthy, Parliamentary Sovereignty: Contemporary Debates (Cambridge University Press 2010) 202-222.

[33] JAG Griffith, ‘The Political Constitution’ (1979) 42 Modern Law Review 1, 19.