Abstract 

This essay examines the constitutional implications of Section 6 of the Retained EU Law (Revocation and Reform) Act 2023, arguing that the provision introduces constitutional instability rather than clarity. While presented as a tool for restoring parliamentary sovereignty and judicial autonomy after Brexit, Section 6 grants UK courts broad discretion to depart from retained EU case law, guided by open-ended statutory factors. This reallocation of interpretive authority does not resolve the uncertainties of Brexit-era law but instead externalises them onto the judiciary.

The essay first traces the evolution of retained EU law from a mechanism of legal continuity to a site of constitutional tension. It then explores Section 6’s implications for three key dimensions: parliamentary sovereignty, the separation of powers and legal certainty. Particular focus is placed on the practical and political burdens now borne by the courts, including their increased visibility in contentious regulatory areas and their exposure to legitimacy risks.

The analysis concludes that Section 6 shifts constitutional responsibility without providing structure or guidance. In doing so, it transforms judicial discretion into judicial vulnerability, destabilising core constitutional principles under the guise of reform. What was framed as a sovereign reassertion may ultimately mark the institutionalisation of constitutional uncertainty.

 

The United Kingdom’s constitutional landscape has undergone a profound change in the wake of Brexit. Central to this transformation is the creation of retained EU law, a legal mechanism initially designed to ensure continuity after leaving the EU, but which has since become a focal point of constitutional tension. Section 6 of the Retained EU Law (Revocation and Reform) Act 2023 marks a turning point: it grants UK courts broad discretion to depart from retained EU case law, guided by newly codified statutory factors.[1] Although framed as a reinforcement of parliamentary sovereignty and judicial autonomy, the provision introduces a new and potentially problematic layer of legal uncertainty.

This essay argues that Section 6 significantly disrupts the balance of power within the UK’s uncodified constitutional framework. By expanding judicial discretion without providing a coherent interpretive framework, it transfers the burden of legal consistency from Parliament to the courts. In doing so, it undermines core constitutional principles such as the rule of law and legal certainty, while exposing judges to accusations of activism in politically contentious areas. What appears to be judicial empowerment is, in reality, a constitutional displacement, one that sees Parliament withdraw from interpretive responsibility, leaving the judiciary to operate in a legally ambiguous environment.

The discussion begins by situating Section 6 within the broader evolution of retained EU law, tracing the shift from legal continuity to constitutional rupture. It then explores the provision’s implications across three interrelated dimensions: parliamentary sovereignty, judicial discretion and the separation of powers, and the principle of legal certainty. The analysis proceeds to assess how Section 6 affects the judiciary’s institutional role in post-Brexit Britain, before concluding with a critical evaluation of whether the provision clarifies the UK’s constitutional framework or simply relocates its uncertainty.

The United Kingdom’s exit from the European Union posed a significant legal dilemma: how to maintain stability in domestic law while removing the binding authority of EU legal norms. To prevent a legislative vacuum, the European Union (Withdrawal) Act 2018 introduced the concept of ‘retained EU law’, a body of law comprising EU regulations, domestically transposed directives, and judgments of the Court of Justice of the European Union (CJEU), all of which continued to apply within UK law post-Brexit.[2] This framework was conceived as a transitional mechanism, aimed at preserving legal continuity while allowing Parliament to revise, replace, or repeal retained provisions over time.

Yet the 2018 Act embedded a deep constitutional tension within the UK’s post-Brexit legal order. While it nominally restored parliamentary sovereignty, it simultaneously preserved the interpretive authority of EU case law by requiring domestic courts to construe retained EU law in accordance with CJEU precedent, unless explicitly authorised to depart.[3] This created a legal fiction of continuity: EU legal influence remained entrenched in domestic jurisprudence, even as political sovereignty was formally reclaimed.[4] As a result, the supposed restoration of sovereignty appeared more symbolic than substantive, prompting criticism from political actors and constitutional scholars alike, who viewed this arrangement as diluting judicial independence and frustrating the intended supremacy of Parliament.

The Retained EU Law (Revocation and Reform) Act 2023, particularly Section 6, was introduced to resolve this unresolved constitutional strain. Section 6 empowers domestic courts to depart from retained EU case law, guided by a new statutory framework. These factors include whether adherence to a CJEU precedent would inhibit the proper development of domestic law and whether such development would better align with the overarching principles of the UK’s constitutional tradition.[5] Crucially, this discretion may be exercised even in the absence of new legislative guidance, effectively vesting substantial interpretive authority in the judiciary. Though presented as a technical recalibration, Section 6 marks a constitutional pivot, reshaping the post-Brexit legal architecture and recalibrating the distribution of legal authority between Parliament and the courts.

While Section 6 may appear to promote judicial independence, it simultaneously shifts interpretive responsibility away from the legislature. By removing the binding force of retained EU case law and failing to provide a comprehensive legislative roadmap, Parliament has effectively delegated the task of legal transition to the judiciary. Though often justified in political discourse as a means of ‘taking back control’,[6] the provision in practice displaces constitutional uncertainty onto the courts. This legislative deflection raises fundamental questions about the nature, direction, and internal coherence of the UK’s evolving constitutional settlement.

On its face, Section 6 appears to represent a reassertion of parliamentary sovereignty. By authorizing domestic courts to disregard retained EU case law, Parliament seems to reclaim interpretive authority from a foreign legal order. Yet this reading is deceptively simplistic. Although the formal supremacy of Parliament remains intact, the practical effect of Section 6 is to delegate core questions of constitutional interpretation to the judiciary. As the Supreme Court affirmed in Miller (No 1), constitutional change of such magnitude must be channeled through Parliament itself, not achieved indirectly through statutory ambiguity.[7] By removing the binding effect of EU precedent without enacting substantive legislative replacements, Parliament has effectively stepped back from its role as the principal architect of legal development.

This delegation further risks diluting the substance of sovereignty itself. In the UK’s constitutional tradition, sovereignty is not merely the power to legislate, but the responsibility to do so with clarity, purpose, and accountability.[8] By withholding detailed statutory guidance while enabling judicial divergence from EU law, Parliament has enacted not a genuine restoration of legislative supremacy, but a form of legislative abdication. What is framed as a sovereign reclamation of interpretive authority is, in practice, a constitutional deflection, one that burdens the courts with responsibilities Parliament has chosen not to discharge.

Section 6 inaugurates a new interpretive regime, one that grants judges broad discretion to depart from retained EU case law by reference to open-ended statutory criteria. While this may appear to enhance judicial autonomy, it does so at the expense of the constitutional separation of powers. Courts are now tasked not merely with interpreting law, but with reconstructing legal doctrine in real time, guided by abstract benchmarks such as the ’proper development’ of domestic law.[9] This marks a sharp departure from the UK’s traditional model of judicial restraint, in which legal change is mediated through precedent, incrementalism, and statutory clarity, not discretionary statutory reinterpretation.

The discretionary model introduced by Section 6 also lacks the institutional safeguards that have historically governed departures from precedent. Under the 1966 Practice Statement, the House of Lords acknowledged its authority to overrule prior decisions, but emphasised that such power must be exercised sparingly, in the interest of legal coherence and certainty.[10] Section 6, by contrast, provides no comparable doctrinal restraint. Judges may now be drawn into resolving not only whether to depart from retained EU law, but how the law should evolve, particularly in politically charged areas such as employment rights, environmental protection, and consumer regulation. As Lord Reed has cautioned, reforms that recast judges as quasi-legislators threaten to erode public confidence in judicial neutrality and, ultimately, the institutional independence of the courts.[11]

This shift profoundly alters the structural logic of the UK’s constitutional order. Traditionally, legislative supremacy has been balanced by judicial interpretation constrained by statute and precedent. Section 6 destabilizes this equilibrium by inviting courts to assume the quasi-legislative role, one in which they are not merely interpreters of existing law, but authors of its future trajectory. The open-ended mandate to pursue the ‘proper development’ of domestic law collapses the distinction between interpretation and creation. In doing so, Section 6 unsettles the separation of powers, not through overt constitutional conflict, but through a functional reallocation of responsibility from Parliament to the judiciary.

One of the most profound constitutional costs of Section 6 lies in its erosion of legal certainty, an essential pillar of the rule of law. Retained EU law once provided a stable and predictable body of doctrine during a period of legal upheaval. Section 6 disrupts that stability by authorizing courts to depart from established precedent using broad and undefined discretionary criteria. As the Supreme Court affirmed in UNISON, legal certainty is not a theoretical aspiration, but a practical prerequisite for fairness, consistency, and the effective operation of justice.[12]

This uncertainty is particularly acute in the context of a common law system that relies on precedent for coherence. Section 6 permits divergent judicial approaches to retained EU case law, especially among lower courts that may be influenced by, but are not necessarily bound to follow, interpretations by superior courts. The result is a doctrinal landscape characterized by inconsistency and fragmentation. In undermining the principle of stare decisis, Section 6 destabilizes the uniformity that individuals, businesses, and institutions depend upon when navigating the law.

In this way, Section 6 does not merely disrupt predictability, it indirectly undermines the rule of law itself. A legal system governed by unclear standards and conflicting precedents risks losing both internal coherence and external legitimacy. As Jack Williams argues, Section 6 offers only the ‘Cheshire Cat’s grin’ of doctrinal clarity: a vanishing structure beneath a politically attractive surface.[13] The breadth of judicial discretion, unanchored to any statutory roadmap, invites legal unpredictability. Catherine Barnard similarly warns that the open-endedness of post-Brexit legislation reflects not constitutional confidence, but institutional fragility, a compromise that leaves courts and litigants without meaningful guidance.[14] Where law becomes indeterminate, its authority begins to dissolve.

The discretion introduced by Section 6 is not merely theoretical; it materially transforms the day-to-day role of the judiciary in post-Brexit Britain. Judges are no longer confined to applying and interpreting EU-derived precedent, but are now active agents in shaping the trajectory of domestic law. This expanded authority, though framed as judicial empowerment, in practice amounts to constitutional exposure. Courts must now determine not only whether to depart from retained EU case law, but also whether such a departure aligns with vague statutory objectives, such as the ‘proper development’ of UK law, objectives for which Parliament has offered neither definition nor doctrinal guidance.

This uncertainty is already surfacing in judicial practice. In TuneIn Inc v Warner Music UK Ltd, the Court of Appeal expressed hesitation in departing from retained EU case law, citing the absence of clear statutory criteria and the risk of legal fragmentation.[15] Such caution reflects a broader institutional concern: without a principled interpretive framework, courts may diverge in their application of Section 6, leading to doctrinal inconsistency and jurisdictional incoherence. The result is not only a departure from EU precedent but also a destabilization of stare decisis, a cornerstone of the UK’s common law tradition.

Consider, for example, a future case involving post-Brexit environmental regulation. A claimant challenges a government rollback by invoking retained EU case law. The Court of Appeal must now decide whether to uphold that precedent or depart from it under Section 6. With no replacement statute and only abstract statutory factors to guide them, the judges face a constitutional dilemma: uphold the EU-based rule and risk appearing resistant to Brexit, or abandon it and undermine legal certainty. What was once a matter of legal interpretation becomes a test of judicial legitimacy.

Upholding the EU-derived standard may be seen as judicial resistance to Brexit; departing from it risks undermining legal certainty. What begins as a question of legal reasoning becomes a test of institutional legitimacy.

Most significantly, Section 6 renders the judiciary more politically visible. In areas formerly governed by harmonised EU standards, such as employment law, environmental protection, and consumer rights, judicial departures may be viewed not as neutral exercises in legal interpretation, but as policy-laden interventions. Judges thus become focal points in contested regulatory debates, assuming roles traditionally reserved for Parliament. This shift blurs the boundary between law and politics, placing the appearance, and substance, of judicial independence at risk. As Lord Reed has cautioned, reforms that compel courts to fill legislative gaps risk undermining the very independence they are purported to preserve.[16] Paul Craig similarly warns that situating courts at the centre of politically sensitive reforms, without clear democratic mandates, exposes them to legitimacy crises for which they are institutionally unequipped.[17]

Supporters of Section 6 often frame it as a necessary correction to the post-Brexit legal settlement, a long-overdue rebalancing of interpretive authority from EU institutions to domestic courts, and by extension, to Parliament. On this view, the provision liberates judges to interpret domestic law in a manner more consistent with the UK’s common law traditions, free from the constraints of an external legal order. Alison Young, for instance, contends that the flexible discretion afforded by Section 6 enhances legal responsiveness and reinforces constitutional pluralism.[18] Others maintain that the capacity to diverge from retained EU case law empowers the UK to cultivate a more authentic, sovereign jurisprudence.

Yet these defenses rest on a fragile foundation. They conflate autonomy with clarity and overlook the burdens that unchecked discretion imposes. Judicial freedom without legislative direction is not constitutional empowerment, it is institutional exposure. Section 6 does not so much enhance judicial independence as it forces courts into constitutional terrain where Parliament has chosen not to legislate. By contrast, codified systems such as Germany and Canada embed safeguards, constitutional courts, override clauses, and explicit interpretive frameworks, to structure judicial discretion.[19] The UK has no such guardrails. To grant open-ended discretion in a system without constitutional anchoring is to invite doctrinal fragmentation and risk eroding the coherence of the common law tradition itself.

Ultimately, the claim that Section 6 strengthens the UK’s constitutional framework misreads both its form and its function. It does not consolidate sovereignty or clarify legal authority; rather, it redistributes uncertainty by externalizing interpretive ambiguity onto the judiciary. Katia De Blasio aptly describes this condition as one of ‘doctrinal instability’, a state in which judges are left to navigate the fault lines of a post-Brexit legal order without a constitutional compass.[20] While the provision may reflect a political desire for flexibility, it achieves this at the expense of constitutional clarity, institutional coherence, and judicial legitimacy, values essential to the stability of any legal order.

 

Conclusion

To conclude, section 6 of the Retained EU Law (Revocation and Reform) Act 2023 was introduced as a mechanism of legislative emancipation, a symbolic severance from EU jurisprudence, and an affirmation of domestic sovereignty. Yet in practice, it performs a far more constitutionally fraught function. Rather than restoring interpretive clarity or consolidating parliamentary control, Section 6 transfers legal uncertainty to the courts, reshaping their role within the constitutional order. Judges are empowered, but unguided; authorized, but exposed. More broadly, the provision exposes a deeper structural fragility within the UK’s uncodified constitution: in the absence of formal guardrails or constitutional clarity, discretion can be granted without responsibility, and authority shifted without reform. What was framed as a sovereign reassertion may ultimately be remembered as the institutionalization of constitutional uncertainty.

 

Footnotes:

[1] Retained EU Law (Revocation and Reform) Act 2023, s 6.

[2] European Union (Withdrawal) Act 2018, s 6.

[3] ibid, s 6(3)–(5).

[4] Mark Elliott, ‘The Legal Fiction of Continuity’ (Public Law, 2019).

[5] Retained EU Law (Revocation and Reform) Act 2023, s 6(2).

[6] HL Deb 6 February 2023, vol 827, col 1016 (Lord Callanan).

[7] R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5, [40].

[8] Mark Elliott, ‘Legislative Responsibility and the Sovereignty Illusion’ (Public Law, 2023).

[9] Retained EU Law (Revocation and Reform) Act 2023, s 6(2). 

[10] Practice Statement (Judicial Precedent) [1966] 1 WLR 1234.

[11] Lord Reed, ‘The Role of the Supreme Court in a Modern Democracy’ (Supreme Court Blog, 2021) https://www.supremecourt.uk/news/the-role-of-the-supreme-court-in-a-modern-democracy.html accessed 26 October 2025.

[12] R (UNISON) v Lord Chancellor [2017] UKSC 51, [66].

[13] Jack Williams, ‘The Cheshire Cat’s Grin’ (EU Relations Law Blog, 2023) https://eurelationslaw.com/blog/the-cheshire-cats-grin-section-6s-appearance-and-disappearance accessed 26 October 2025.

[14] Catherine Barnard, ‘Legal Certainty after Brexit’ (UK Constitutional Law Association Blog, 2023) https://ukconstitutionallaw.org accessed 26 October 2025.

[15] TuneIn Inc v Warner Music UK Ltd [2021] EWCA Civ 441, [52]–[53].

[16] Lord Reed, ‘The Role of the Supreme Court in a Modern Democracy’ (Supreme Court Blog, 2021) https://www.supremecourt.uk/news/the-role-of-the-supreme-court-in-a-modern-democracy.html accessed 26 October 2025.

[17] Paul Craig, ‘Brexit and Judicial Power’ (2023) Public Law 214.

[18] Alison Young, ‘Flexible Sovereignty Post-Brexit’ (UK Constitutional Law Association Blog, 2023) https://ukconstitutionallaw.org accessed 26 October 2025.

[19] See, eg, Basic Law for the Federal Republic of Germany, art 100; Canadian Charter of Rights and Freedoms 1982, s 33.

[20] Katia De Blasio, ‘Interpreting Uncertainty after Brexit’ (UK Constitutional Law Association Blog, 2024) https://ukconstitutionallaw.org accessed 26 October 2025 accessed 26 October 2025.