Fragility and Reform: Stress-Testing the UK’s Uncodified Constitution in an Era of Crisis

Introduction 

The United Kingdom’s uncodified constitution praised for its flexibility and withstanding the test of time, does face an unprecedented strain. Brexit litigation, the ‘prorogation crisis,’ rights-restricting statutes such as the Illegal Migration Act 2023 and Rwanda Act 2023 and Section 35 veto on Scottish legislation have exposed structural weaknesses in a system heavily reliant on conventions and political self-restraint. Executive dominance through skeleton bills and Henry VIII powers, alongside the erosion of judicial independence and the prominent disregard for devolved consent, elucidates how fragile a framework lacking codified aspects can be. These developments thus challenge the traditional claim that constitutional balance, alone is secured by political accountability. This article asks whether partial codification, targeting prerogative limits, rights protection, and devolution consent has become necessary. 

The Nature and Logic of the Uncodified Constitution 

The central aspect within the UK’s constitutional structure stands parliamentary, classically defined by Oxford theorist A.V Dicey as Parliament’s “right to make or unmake any law whatever,” a formulation that illustrates legislative omnipotence even limiting the explanation regarding its drawbacks [1]. Courts have clarified that this supremacy is a judicially recognised principle in application. For instance, in Jackson and others v Her Majesty’s Attorney General [2005] UKHL 56, Lord Steyn described it as “a construct of the common law,” and Baroness Hale cautioned that “the courts will treat with particular suspicion (and might even reject) any attempt to subvert the rule of law by removing governmental action affecting the rights of the individual from all judicial scrutiny” [2]. Therefore, these illustrations situate the sovereignty within a structural rule-of-law that the judiciary applies and upholds. 

That framework has deep common‑law roots. In Entick v Carrington & Ors [1765] EWHC KB J98 the courts established that executive action must have legal authority [3]; and in R (on the application of Evans) and another (Respondents) v Attorney General (Appellant), Lord Neuberger affirmed that allowing a minister to overrule a judicial decision “would cut across two constitutional principles… (1) a decision of a court is binding… and cannot be ignored or set aside by anyone, including… the executive; (2) decisions and actions of the executive are… reviewable by the court” [4].  This pairing regarding Entick’s insistence on legal warrant and Evans’s affirmation of judicial supremacy over executive discretion illustrates how, even absent a codified text, the common law applies limitations of enforcement on governmental power [4]. 

By contrast, the discipline furnished by conventions remains political which is the uncodified model’s central vulnerability. For instance, the Sewel Convention is indispensable to managing the interface between reserved and devolved competences and is recognised in Scotland Act 1998, s 28(8) (inserted by Scotland Act 2016, s 2), but held nonjusticiable as Miller (No 1) confirmed so it neither binds Westminster nor furnishes courts with a rule to invalidate legislation enacted without consent [5]. Lord Sewel’s original statement that Westminster “would not normally legislate with regard to devolved matters in Scotland without the consent of the Scottish Parliament,” therefore depends on political will, a fragility exposed during Brexit‑era legislation and renewed centralisation [6]. Nevertheless, having accepted the Miller claimants’ arguments about the inevitable domestic effects of triggering Article 50, thus collapsing the distinction between action on the international and domestic planes, it was difficult for the Supreme Court majority to resist the logic that the devolution statutes would also be affected. 

Even if the devolution statutes were necessarily affected by the triggering of Article 50, the claim that withdrawal legislation would therefore engage the Sewel Convention encountered an additional difficulty. The UK Government noted, and the Supreme Court accepted, that devolved consent had not been sought for earlier EU‑related legislation, including the European Communities (Amendment) Act 2002, the European Parliamentary Election Act 2002, the European Union Amendment Act 2008, the European Union Act 2011 and the European Union Referendum Act 2015 [7]. At the same time, the constitution’s celebrated evolutionary capacity, an incremental change through ordinary statutes and case law which has produced imperative institutional re‑designs such as the Human Rights Act 1998 and Constitutional Reform Act 2005 and rapid crisis‑era responses including the Coronavirus Act 2020, but because these changes are not well-established in a superior law, they remain susceptible to displacement by later Acts or expansive delegated powers. In short, the uncodified constitution’s strengths, ‘flexibility, adaptability, political accountability’ are increasingly offset by its structural gaps as sovereignty without explicit constitutional limits, legality without entrenched supremacy and conventions whose force depends on the very self‑restraint recent crises have put in doubt.  

Constitutional Stress-Testing 2016-2025 

The decade from 2016 to 2025 has functioned as an extended stress test of the uncodified constitution, compelling courts and Parliament to confront the uncertain aspects of prerogative power, rights protection and territorial governance. In Miller I (2017), the Supreme Court held that the executive could not trigger Article 50 without an Act of Parliament both reinforcing parliamentary sovereignty and exposing the unsettled scope of the foreign affairs prerogative. As the Court observed, the constitutional weight of notification is not diminished by its brevity: “A notice under article 50(2) could no doubt be very short indeed, but that would not undermine its momentous significance” [8]. The litigation thus illustrated that decisions of “momentous significance” require statutory authorisation rather than executive fiat, with the Court expressly framing the disputes around the UK’s “constitutional requirements” for withdrawal. Two years later, the prorogation crisis pressed the system’s reliance on conventions to breaking point. In Miller/Cherry (2019), the Court held prorogation justiciable “an issue which can be resolved by the application of that standard is by definition one which concerns the extent of the power to prorogue, and is therefore justiciable” and, on the facts, unlawful: “It is impossible for us to conclude… that there was any reason—let alone a good reason—to advise Her Majesty to prorogue Parliament for five weeks… It follows that the decision was unlawful” [9]. In the absence of codified standards, adjudication became the only avenue to prevent suspension of parliamentary scrutiny at a constitutional inflection point. 

Simultaneously, ordinary legislation re‑shaped the territorial constitution. The United Kingdom Internal Market Act 2020 centralised regulatory authority through mutual recognition and non‑discrimination rules for goods, constraining devolved competence and provoking sustained criticism from Scotland and Wales. The Act’s mutual recognition principle states that goods lawfully sold in one part of the UK “should be able to be sold in any other part… free from any relevant requirements that would otherwise apply,” with detailed definitions of “relevant requirements” ranging from product characteristics to robust documentation [10]. The statute also restricts the use of manner‑of‑sale rules to circumvent mutual recognition and provides commencement and continuity provisions that establish the new market structure. In parallel, Section 35 of the Scotland Act was used for the first time to veto Scotland’s Gender Recognition Reform Bill, demonstrating that consent‑based conventions are no substitute for juridically enforceable limits when central override mechanisms exist; the veto prohibits the Presiding Officer from submitting the bill for Royal Assent, directly engaging the balance between devolved autonomy and central authority [11]. These developments arrived against a background of repeated disregard of the Sewel Convention as discussed, confirming its non‑legal character and the fragility of the devolution settlement when consent rules are political rather than juridical. 

The decade’s rights and legality controversies further exposed structural weaknesses. The Illegal Migration Act 2023 contains robust clauses limiting judicial oversight, inviting conflict with the principle that such clauses cannot exclude review for jurisdictional error, famously restated in Anisminic v Foreign Compensation Commission [1969] 2 AC 147 [12]. The Safety of Rwanda (Asylum and Immigration) Act 2024 escalates the tension by disapplying international obligations and purporting to override the Supreme Court’s factual findings in AAA v SSHD [2023] UKSC 42 where deficiencies in Rwanda’s asylum system created “substantial reasons for believing that there is a real risk of refoulement” [13]. In AAA, the Court concluded that removal of asylum seekers to Rwanda will be unlawful under Section 6 of the Human Rights Act 1998. This is because it would breach Article 3 of the European Convention on Human Rights (ECHR), which prohibits torture and inhuman or degrading treatment. These are the very facts the Rwanda Act attempts to legislate around, pitting claims of legislative supremacy against established legality and adjudicated fact. The combined effect is to place courts and ministers on a collision course, testing whether the uncodified order can resist ordinary‑statute attempts to recalibrate rights and facts without ingrained constitutional supremacy. 

Finally, executive dominance has widened through procedural levers. Post‑Brexit legislation increasingly relies on skeleton bills and broad Henry VIII powers, repeatedly criticised by the Delegated Powers and Regulatory Reform Committee (2021–2024) as unacceptable transfers of legislative power to ministers, developments that dilute ordinary scrutiny and blur the line between executive rule‑making and primary legislation A skeleton bill—sometimes called a framework bill—is legislation that sets out broad policy principles but omits substantial detail on how those principles will be implemented. Instead, it delegates wide powers to ministers or other authorities to supply the detail later, usually through delegated legislation (secondary or subordinate legislation) enacted after the bill has passed both Houses and become law. Individual provisions that adopt this approach are known as skeleton clauses [14]. 

The House of Lords Delegated Powers and Regulatory Reform Committee (DPRRC) scrutinises bills for such delegated powers. In its guidance to departments, the DPRRC defines a skeleton bill or clause as one where “the provision on the face of the bill is so insubstantial that the real operation of the Act, or sections of an Act, would be entirely by the regulations or orders made under it” [15]. The DPRRC states that skeleton legislation should be used only in “the most exceptional circumstances.” Routine reliance on such bills undermines core principles of parliamentary democracy, particularly the accountability of the executive to Parliament. This is because primary legislation undergoes detailed scrutiny and can be amended, whereas statutory instruments (SIs)—the most common form of delegated legislation—cannot be amended and are rarely rejected. As a result, skeleton bills significantly weaken parliamentary oversight. 

Several committees, including the DPRRC, the House of Lords Constitution Committee, and the Secondary Legislation Scrutiny Committee (SLSC), have criticised the Government’s increasing use of skeleton legislation [16]. In its November 2018 report on delegated powers, the Constitution Committee identified skeleton bills as a “recurring problem” and warned: 

“Skeleton bills inhibit parliamentary scrutiny, and we find it difficult to envisage any circumstances in which their use is acceptable [17]. The Government must provide an exceptional justification for them; it cannot rely on generalised assertions of the need for flexibility or futureproofing.” 

The Committee further noted that when SIs are used to implement significant policy decisions, Parliament is “doing little more than rubber-stamping the Government’s secondary legislation,” a practice it deemed “constitutionally unacceptable.” It cautioned that if this trend continues, the Lords’ traditional restraint toward secondary legislation may not hold. Although rare, the Lords have previously considered rejecting SIs made under skeleton powers. The Joint Committee on Conventions (2006) concluded that it could be consistent with the Lords’ revising role to defeat an SI where the parent Act was a skeleton bill and the SI contained provisions normally found in primary legislation. 

The Government’s response to the 2018 report acknowledged that bills with “unduly vague powers” are usually unacceptable but argued that skeleton bills can be justified where the policy framework is clear and delegated powers are needed to fill in technical detail. Lord Young of Cookham reiterated this position during debate, stating that a bill setting out a clear framework but using delegated powers for detail “may be justifiable in some cases.” 

Conclusion 

The past decade has exposed the fragility of the UK’s uncodified constitution. While its flexibility has historically been praised, recent crises from Brexit litigation and unlawful prorogation to rights restricting statutes and devolved vetoes, demonstrate that reliance on conventions and political self-restraint is no longer sufficient. Executive dominance, the erosion of judicial oversight and disregard for devolved consent reveal structural gaps that threaten stability and legitimacy. A codified constitution, whether full or partial, offers a principled solution: establishing foundational democratic values, clarifying institutional powers, securing rights and enforcing territorial guarantees. By relocating constitutional authority from parliamentary fiat to popular sovereignty and integrating enforceable limits, codification could transform the UK’s constitutional order from one of political discretion to one of legal certainty and therefore preserving adaptability without sacrificing the rule of law. 

References 

[1] A V Dicey, Introduction to the Study of the Law of the Constitution (10th edn, Macmillan 1959) 39–40. Available at: https://constitution.org/1-Constitution/cmt/avd/law_con.htm  

[2] Jackson v Attorney General [2005] UKHL 56, [102] (Lord Steyn), [159] (Baroness Hale). Available at: Jackson v HM Att Gen.doc 

[3] Entick v Carrington (1765) 19 St Tr 1029. Available at: : National Case Law Archive | Case summaries and analysis 

[4] R (Evans) v Attorney General [2015] UKSC 21, [52] (Lord Neuberger). Available at:  R (on the application of Evans) and another (Respondents) v Her Majesty's Attorney General (Appellant) - UK Supreme Court 

[5] Scotland Act 1998, s 28(8) (as inserted by Scotland Act 2016, s 2). Available at: Scotland Act 2016 

[6] [9] R (Miller) v Prime Minister; Cherry v Advocate General for Scotland [2019] UKSC 41, [50]–[61]. Available at: R (on the application of Miller) (Appellant) v The Prime Minister (Respondent) and Cherry and others (Respondents) v Advocate General for Scotland (Appellant) (Scotland) 

[7] [8] R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5, [79]–[94]. Available at:  R (on the application of Miller) (Appellant) v The Prime Minister (Respondent) and Cherry and others (Respondents) v Advocate General for Scotland (Appellant) (Scotland) 

[10] United Kingdom Internal Market Act 2020, Part 1. Available at: United Kingdom Internal Market Act 2020 

[11] Section 35 Scotland Act 1998. Available at:  Scotland Act 1998 

[12] Webb, T. (2023). Essential Cases: Public Law. 6th edn. Oxford: Oxford University Press. Available at: https://www.oxfordlawtrove.com/10.1093/he/9780191995729.001.0001/he-9780191995729-chapter-3 

[13] R (AAA and others) v Secretary of State for the Home Department [2023] UKSC 42, [85]–[90]. Available at:  R (on the application of AAA and others) (Respondents/Cross Appellants) v Secretary of State for the Home Department (Appellant/Cross Respondent) - UK Supreme Court 

[14] House of Lords Library, Skeleton bills and delegated powers (21 Dec 2021) Available at:  https://lordslibrary.parliament.uk/skeleton-bills-and-delegated-powers/ 

[15] Joint Committee on Convention Report. Available at: Microsoft Word - Report Printers version.doc 

[16] Delegated Powers and Regulatory Reform Committee, Democracy Denied? The urgent need to rebalance power between Parliament and the Executive (HL Paper 106, 2021) ch 2, paras 16–17. Available at: https://publications.parliament.uk/pa/ld5802/ldselect/lddelreg/106/106.pdf 

[17] House of Lords Select Committee on the Constitution (2018) The Legislative Process: The Delegation of Powers. 16th Report of Session 2017–19. HL Paper 225. London: House of Lords. Available at: The Legislative Process: The Delegation of Powers 

Bibliography  

Books 

AV Dicey, Introduction to the Study of the Law of the Constitution <https://constitution.org/1-Constitution/cmt/avd/law_con.htm> accessed 28 December 2025. 

Cases 

Jackson v Attorney General [2005] UKHL 56. 

Entick v Carrington (1765) EWHC KB J98. 

R (Evans) v Attorney General [2015] UKSC 21. 

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

R (Miller) v Prime Minister; Cherry v Advocate General for Scotland [2019] UKSC 41. 

R (AAA and others) v Secretary of State for the Home Department [2023] UKSC 42. 

Anisminic Ltd v Foreign Compensation Commission [1969] 2 AC 147. 

R v Secretary of State for Transport, ex p Factortame Ltd (No 2) [1991] 1 AC 603; Case C213/89 Factortame (CJEU, 1990). 

Legislation 

Scotland Act 1998, s 35. 

Scotland Act 2016, s 2. 

Human Rights Act 1998, ss 3, 6. 

Constitutional Reform Act 2005. 

Coronavirus Act 2020. 

United Kingdom Internal Market Act 2020, Part 1. 

Fixed term Parliaments Act 2011 (repealed). 

Dissolution and Calling of Parliament Act 2022. 

Illegal Migration Act 2023. 

Safety of Rwanda (Asylum and Immigration) Act 2024. 

Articles and Reports 

Delegated Powers and Regulatory Reform Committee Reports 2021–2024. 

Image Credits

Paul Silvan on Unspalsh <https://unsplash.com/photos/brown-concrete-building-near-body-of-water-during-daytime-Nv1-l_xZnV4>