Keeping power in check — Judicial review, parliamentary sovereignty and the rule of law in the UK

Emma Wills article examines the role of judicial review in sustaining the rule of law within the UK’s uncodified constitutional framework.

Abstract

This article considers the tension between political and legal forms of accountability, the scope of prerogative powers and the challenges posed by the doctrine of parliamentary sovereignty. Drawing on leading case law, it argues that judicial review constitutes an indispensable safeguard against executive dominance within parliament, ensuring that discretionary powers are exercised lawfully and subject to effective oversight. In highlighting the judiciary’s role in preserving constitutional balance and democratic legitimacy, the article contends that the preservation and potential enhancement of judicial review is essential to maintaining the integrity of the UK’s constitutional order.

Introduction

The UK’s lack of a written constitution places exceptional reliance on the rule of law and an independent judiciary as safeguards against the arbitrary exercise of governmental power.¹ At the heart of the British constitutional framework lies the doctrine of the rule of law, understood as the “recognition and acceptance of a legal order underpinning the functions of governmental bodies and agencies, particularly in their relationships with the citizen”.² This principle is important in ensuring that the government does not treat citizens unfairly simply because it holds power.

Yet the constitutional principle of parliamentary sovereignty, described in classic Diceyan terms as parliament’s right to “make or unmake any law whatever”,³ appears in tension with this framework. Since the executive derives its authority from and is situated within parliament, its actions must be constrained by law. The executive, comprising the prime minister and cabinet ministers, is responsible for formulating and implementing government policy and exercising the powers of the Crown. 

Crucially, parliament may confer broad discretionary powers upon the executive, raising the imperative of legal scrutiny not only over whether those powers are exercised, but whether they are lawfully exercised.⁴ Judicial review has sometimes been criticised on grounds of democratic legitimacy, but its function is confined to resolving legal rather than political questions. It thereby serves as a critical mechanism for upholding the rule of law in a polity characterised by flexible constitutional arrangements.

The rule of law and judicial review in the UK

Two principal mechanisms hold the government to account: political scrutiny,⁵ through parliament, the media and public opinion; and legal scrutiny, through judicial review by the independent judiciary.⁶ Judicial review is a cornerstone of the rule of law the rule of law is a “fundamental” aspect of the UK’s constitution.⁷ Consequently, government proposals to restrict the availability of the judicial review have been controversial, as they risk undermining the rule of law⁸ and fostering corruption through diminished oversight of the actions of government and public bodies.⁹ 

Parliamentary concern about proposals to restrict judicial review has at times been expressed in striking terms. For example, Lord Beecham remarked that, “in the unlikely event of Mr Putin becoming aware of the government’s approach, he would be lost in admiration”.¹⁰ While rhetorical in nature, such interventions illustrate the perceived constitutional risks of diminishing judicial oversight, namely that an executive supported by a compliant legislature may erode established constraints on governmental power.

Given the overlap in the separations of powers due to the executive sitting in the sovereign parliament, it is essential that the flexible nature of the UK’s political constitutional framework is not abused. The UK’s political constitution differs markedly from systems governed by codified constitutions, which place explicit limits on institutional powers. In the UK, parliament remains sovereign and can confer extensive authority on the executive. Given the executive’s increasing dominance of the House of Commons, the risk emerges that judicial decisions adverse to the government may be overridden by swift legislative amendment. This constitutional pliability stands in contrast with the EU’s legal order, which imposed binding constraints on member states. 

Comparative experience also underscores the importance of judicial oversight in maintaining constitutional balance. In Germany, the Federal Constitutional Court has consistently limited executive action by reference to constitutional rights and principles, while in Canada the Supreme Court has developed doctrines such as the ‘unwritten constitutional principles’ of democracy and the rule of law to constrain governmental power. Although the UK does not have a codified constitution, these examples demonstrate how courts in other common law and civil law jurisdictions alike act as constitutional guardians, providing a useful lens through which to evaluate the evolving role of judicial review in the UK.

Lord Steyn’s observation that Dicey’s account of parliamentary sovereignty is “out of place in the modern United Kingdom” reflects the transformation catalysed by EU membership. Under the European Communities Act 1972, courts were empowered to override domestic legislation in conflict with EU law. For example, the courts held the government’s failure to meet EU air quality standards to be unlawful, compelling urgent remedial action.¹¹ The importance of legal scrutiny was underscored when the judge notably remarked that “promises are not enough and it seems the court must keep the pressure on to ensure compliance is actually achieved”.¹² While some may criticise the court for overstepping its authority by permitting a subsequent judicial review case to be brought without application for permission, others may view this as a necessary response to the executive’s repeated failure to comply with the law and the need for effective enforcement. 

It has been submitted that a state may “only claim to uphold the rule of law if it provides effective means for the prevention and redress of illegal action by those who wield public powers”.¹³ Judicial review, in this sense, is a constitutional safeguard, compelling public authorities to exercise discretion within a defined legal framework and to adopt decision-making processes that prevent arbitrariness. It allows for scrutiny of decisions and decision-making processes, in turn requiring for there to be structure in the way that decisions are taken in order to avoid arbitrary exercises of power.¹⁴ 

This is important in a system where parliament may delegate expansive powers to the executive. The quantity of power conferred is not generally challengeable. Rather, judicial review assesses whether such powers are exercised lawfully, consistent with both the enabling statute and the broader constitutional context.¹⁵ Under the doctrine of parliamentary sovereignty, if parliament has given the executive very wide powers, the assumption that the courts must take is that parliament intended for those powers to be wide.¹⁶ Importantly, courts do not substitute their own judgments for those of decision-makers; rather, they enforce the boundaries of legal authority.¹⁷ Where a decision is found to be unlawful, the court will grant an order but will not impose its own decision.¹⁸ 

Judicial review allows anyone with sufficient interest to legally challenge the decisions of public bodies that have been granted decision-making powers by parliament,¹⁹ ensuring that the rule of law is upheld. This is significant, as in the political forum, issues that often arise relate to contradicting opinions,²⁰ whereas the courts are concerned with holding the executive to account in terms of the law. 

This was evident in R (Miller) v Secretary of State for Exiting the European Union where the government’s reliance on the royal prerogative to trigger Article 50 of the Lisbon Treaty was found to be unlawful.²¹ A political response shaped by the executive’s dominance and electoral pressures may well have upheld the decision. The judiciary, however, focused solely on the legality of the process, not its political merits. While the judgment had inevitable political consequences, the court’s concern lay squarely with the constitutional allocation of power.

Political versus legal scrutiny

As has been observed, “an executive government with its hands on the levers of sovereign legislative authority has to suffer only as much scrutiny via judicial review as it is prepared to tolerate”.²² Courts have long accepted the primacy of parliament, but the growing consolidation of executive power within parliament threatens to distort the separation of powers.²³ While the UK’s constitutional framework does not mandate a strict separation, it depends on the functional independence of each branch and mutual institutional respect.²⁴

Although the judiciary recognises parliamentary sovereignty as a constitutional cornerstone, there are indications that it may treat certain principles, such as judicial review, as constitutional fundamentals, potentially immune even from legislative abrogation.²⁵ The courts have intimated a willingness to intervene to protect judicial review as a ‘constitutional fundamental’ that not even parliament could abolish.²⁶

Some scholars suggest that, since judges created the principle of parliamentary sovereignty it is therefore “not unthinkable that circumstances could arise where the courts may have to qualify a principle established on a different hypothesis of constitutionalism”.²⁷ While largely theoretical, this argument too reinforces the judiciary’s institutional commitment to protecting the rule of law from legislative or executive encroachment.²⁸ Such judicial intervention could challenge the firmness of parliamentary sovereignty.²⁹ 

In practice, however, judicial review of primary legislation remains off-limits.³⁰ Parliament retains the legal authority to limit judicial review, though courts may respond by interpreting such restrictions narrowly to preserve constitutional principles. In this way, judicial restraint coexists with judicial vigilance. Yet, if parliament affirms that it does not wish to undermine the rule of law, judges may feel more comfortable interpreting government measures in a manner that aligns with this principle, thereby limiting the practical effect of restrictive proposals.³¹ 

Parliamentary sovereignty and the judicial role

Critics often contend that judicial review suffers from a democratic deficit, given that judges are unelected and therefore lack a representative mandate.³² Parliament, by contrast, is comprised of elected officials and is thus better positioned, under a theory of representative democracy, to determine the public interest. Under parliamentary sovereignty, the executive must act in accordance with parliament’s wishes.³³ Consequently, some argue that judges should not interfere with decisions made by bodies accountable to parliament. Yet this argument overlooks that many of the bodies subject to judicial review are themselves unelected. 

The role of the judiciary is to uphold legal principles and constitutional values.³⁴ If judges were subjected to elections, or were granted power to strike down decisions or legislation, this would compromise the legal nature of their role and introduce political pressure in the form of both ministerial and public criticism thus undermining judicial impartiality.³⁵ Moreover, judicial invalidation of legislation would risk creating legal uncertainty and gaps in the law, an outcome that the unwritten UK constitution seeks to avoid.³⁶

Tensions between executive and judiciary often surface when judicial review is used as a means to delay or quash governmental decisions,³⁷ or when it becomes a tool for political campaigning.³⁸

While it is important not to stifle the ability of public authorities to exercise their decision-making responsibilities and function effectively,³⁹ even the prospect of judicial review can deter unlawful action.⁴⁰ While judicial review may cause some public bodies to act with excessive caution, any attempt to curtail it would risk weakening the rule of law. Given the executive’s increasing ability to marginalise opposition and dominate parliament, maintaining and enhancing access to judicial review is vital for safeguarding legal accountability.⁴¹

As judicial review grows in importance, mirroring the executive’s increasing dominance in overriding institutional checks or opposition and exerting its power,⁴² public confidence in legal accountability also becomes more essential. Reducing access to judicial review may therefore exacerbate, rather than resolve, public concerns over executive overreach.

Prerogative powers and judicial limits

Royal prerogatives represent the residual powers of the Crown that have not yet been placed in statute.⁴³ Historically, such powers were immune from judicial scrutiny, provided they remained within their defined scope. The landmark case of Council of Civil Service Unions v Minister for the Civil Service (GCHQ) marked a significant constitutional development, confirming that prerogative powers, like statutory powers, are subject to judicial review where their exercise affects individual rights or legitimate expectations. 

This does not apply strictly to all prerogative powers however, only those that are ‘justiciable’.⁴⁴ Decisions concerning national security, for example, remain within the political domain.⁴⁵ Nevertheless, the courts will review prerogative powers where their exercise affects the rights or freedoms of individuals.⁴⁶ The inclusions of Orders in Council within the scope of review confirms that judicial scrutiny has expanded significantly.⁴⁷

While prerogative powers may be justified by considerations of expediency, particularly in emergencies,⁴⁸ their non-statutory origin renders them vulnerable to abuse. The judiciary therefore plays a central role in identifying the scope and limits of such powers.⁴⁹ This function becomes crucial when the executive acts for immediate policy objective, or in ways that exceed its constitutional remit,⁵⁰ particularly given that some dated prerogatives stem from eras when the monarchy had absolute powers.⁵¹

The case of Miller⁵² illustrates this dynamic. The government, relying on prerogative power to make or unmake treaties, argued that the European Communities Act 1972 did not confer any rights on individual. The courts rejected this view, confirming that the European Communities Act 1972 had given rise to enforceable individual rights, and that only parliament, not the executive, could withdraw rights granted under statute.⁵³ The judgment represented a “vital reaffirmation” of parliamentary sovereignty,⁵⁴ which is important in the context of the UK’s flexible constitutional framework. Moreover, this outcome would not have been possible without an individual initiating judicial review. However, the fact that three of the 11 justices dissented highlights the element of judicial subjectivity in interpreting legality, particularly given the unelected nature of the judiciary.⁵⁵

The limits of prerogative power were further clarified in R (Miller) v The Prime Minister and Cherry v Advocate General for Scotland (Miller II).⁵⁶ In that case, the Supreme Court held the government’s advice to prorogue parliament unlawful, as it had the effect of frustrating constitutional principles without reasonable justification. Unlike Miller I, which centred on the allocation of powers between parliament and the executive, Miller II underscored the judiciary’s role in ensuring that prerogative powers cannot be exercised in a manner that undermines parliamentary accountability. This decision represents one of the strongest affirmations of the judiciary’s constitutional role in checking executive overreach within the UK’s flexible constitutional framework.

Further examples of executive overreach include Westminster’s assertion that post-Brexit powers returning from the EU would not be devolved.⁵⁷ This suggested a willingness to override institutional checks and reduce opposition scrutiny. In Evans v Attorney General, the Supreme Court struck down the ministerial veto of a judicial decision requiring disclosure of the Prince of Wales’ correspondence with government ministers (the so-called ‘black spider memos’).⁵⁸ The court emphasised that permitting the executive to override a judicial decision would undermine the rule of law and judicial independence. The case therefore illustrates the judiciary’s willingness to limit executive reliance on statutory veto powers where such reliance is inconsistent with constitutional principles.

In summary

This article demonstrates that judicial review is indispensable in the UK’s flexible constitutional framework, particularly in mitigating risks from executive dominance within parliament. One scholar has observed that, “the constitution presupposes that constitutional actors – judges as well as politicians – will exercise restraint by reference to shared, if not wholly articulated, understandings of the limits of constitutional acceptability”.⁵⁹ The doctrine of separation of powers depends not only on formal boundaries, but on mutual respect and institutional self-restraint. The executive must recognise that the judiciary performs a constitutionally mandated role: not to obstruct governance, but to uphold the rule of law as a foundational principle.⁶⁰ 

In light of the growing concentration of executive power and the absence of entrenched constitutional limits, the preservation, if not the enhancement, of judicial review is essential to maintaining constitutional equilibrium.

Judicial review remains a cornerstone of the rule of law, particularly in a legal system that lacks a codified constitution. Absent of such oversight, political expediency risks displacing legal principle, eroding the constraints that protect individual rights and institutional integrity. It has been rightly said that democracy is not merely just ballot box voting, it is also about the public’s ongoing ability to participate in governance and to hold those who wield public power legally accountable.⁶¹

Emma Wills is a solicitor at SSE PLC, Edinburgh.

Footnotes

1 Ashton, C and Finch, V (2000) Constitutional Law in Scotland. W Green/Sweet and Maxwell, p62.

2 The Laws of Scotland. Stair Memorial Encyclopaedia Constitutional Law (Reissue), para 1.

3 Dicey, AV (1965) The Law of the Constitution.10th edn. Macmillan, pp39-40.

4 Ashton, C and Finch, V (2000) Constitutional Law in Scotland. W Green/Sweet and Maxwell, p62.

5 White, H (2015) Parliamentary Scrutiny of Government. Institute for Government, p4.

6 Ministry of Justice (2013) Judicial Review Proposals for Further Reform (Cm 8703), para 21.

7 House of Lords Constitution Committee (2013) Examination of Witnesses, per Lord Hope.

8 Ministry of Justice (2012) Judicial Review: Proposals for Reform (Cm 8515), para 11.

9 Select Committee on Constitution (2007) ‘Appendix 5: Paper by Professor Paul Craig: The Rule of Law’; Bistrong, R (2015) ‘Corruptions Impact on the Rule of Law & Security: Moving from the Vicious to the Virtuous’ (Accessed at: https://www.richardbistrong.com/corruptions-impact).

10 House of Lords (2014) Hansard, Vol 757: debated 9 December 2014, column 1742.

11 Harvey, F (2018) ‘Air pollution: UK government loses third court case as plans ruled “unlawful”’, The Guardian; The Queen (on the application of ClientEarth) No.3 v Secretary of State for Environment, Food and Rural Affairs and ors [2018] EWHC 315 (Admin).

12 ClientEarth (2018) ‘Legal history made in ClientEarth case as judge makes “exceptional” ruling’ (Accessed at: https://www.clientearth.org/latest/news/legal-history-made-in-clientearth-case-as-judge-makes-exceptional-ruling).

13 Turpin, C and Tomkins, A (2007) British Government and the Constitution: Text and Materials. Cambridge University Press, p86.

14 The Laws of Scotland. Stair Memorial Encyclopaedia Constitutional Law (Reissue), para 30.

15 Public Administration Committee (2010) ‘Too many ministers?’; BBC (2010) ‘Number of ministers should be cut by a third, say MPs’.

16 Edinburgh and Dalkeith Railway Co v Wauchope [1842] 8 Cl & F 710; Pickin v British Railways Board [1974] AC 765.

17 Delaney, EF (2014) ‘Judiciary rising: constitutional change in the United Kingdom’, Northwestern University Law Review, 108(2), pp543, 554.

18 Senior Courts Act 1981, Sections 31(1), (2).

19 Cooke, R (1997) Turning Points of the Common Law. Sweet and Maxwell, p74; R v Hull University Visitor, ex P [1993] AC 682 [693] (Lord Griffiths).

20 White, H (2015) Parliamentary Scrutiny of Government. Institute for Government, p4.

21 R (on the application of Miller and another) (Respondents) v Secretary of State for Exiting the European Union (Appellant) [2017] UKSC 5 [3].

22 Elliott, M (2014) ‘What a (for now failed) attempt to curb judicial review tells us about the UK’s constitution’, Public Law for Everyone.

23 R v HM Treasury, ex parte Smedley [1985] 1 All ER 589 [593].

24 Ashton, C and Finch, V (2000) Constitutional Law in Scotland. W Green/Sweet and Maxwell, p50.

25 House of Lords Constitution Committee (2013) Examination of Witnesses, per Lord Neuberger.

26 R (Jackson) v Attorney General [2005] UKHL 56, para 102.

27 Jackson v Attorney General [2006] 1 AC 262 [102] (Lord Steyn); European Scrutiny Committee (2010) ‘The EU Bill and parliamentary sovereignty’.

28 Bingham, T (2010) The Rule of Law. Penguin Books, p168.

29 Street, A (2013) Judicial Review and the Rule of Law: Who is in Control? The Constitution Society, p10.

30 R (Wheeler) v Office of the Prime Minister [2008] EWHC 1409 (Admin).

31 Street, A (2013) Judicial Review and the Rule of Law: Who is in Control? The Constitution Society, p47.

32 Ibid.

33 Public Law Project (2013) ‘Public Law Project response to the judicial review: proposals for further reform consultation’.

34 Street, A (2013) Judicial Review and the Rule of Law: Who is in Control? The Constitution Society, p16.

35 Political and Constitutional Reform Committee (2014) Constitutional role of the judiciary if there were a codified constitution (HC 802), para 39.

36 Political and Constitutional Reform Committee (2014). Constitutional role of the judiciary if there were a codified constitution (HC 802), para 44.

37 The Laws of Scotland. Stair Memorial Encyclopaedia Constitutional Law (Reissue), para 30.

38 Ministry of Justice (2013) Judicial Review Proposals for Further Reform (Cm 8703), p3.

39 Wagner, A (2012) ‘A war on judicial review [updated]’, UK Human Rights Blog.

40 Elliott, M (2012) ‘Judicial review – why the Ministry of Justice doesn’t get it’, UK Constitutional Law Association.

41 Ministry of Justice (2013) Judicial Review Proposals for Further Reform (Cm 8703), para 35.

42 Le Roux, N (2017) ‘Over-mighty executive: since 1997, Britain has been drifting towards elective dictatorship’, Democratic Audit UK.

43 Dicey, AV (1959) An Introduction to the Study of the Law of the Constitution.10th edn. Liberty Fund Inc, p464.

44 Bradley, A, Ewing, K and Knight, C (2015) Constitutional and Administrative Law. 16th edn. Pearson, pp260-1.

45 Public Administration Select Committee (2004) Taming the Prerogative: Strengthening Ministerial Accountability to Parliament (Fourth Report) (HC 422), p15.

46 Ibid; R v Secretary of State for Foreign Affairs ex p Everett [1989] 1 QB 811.

47 R v Secretary of State for Foreign and Commonwealth Affairs, ex p Bancoult (No 2) [2008] UKHL 61.

48 Public Administration Select Committee (2004) Taming the Prerogative: Strengthening Ministerial Accountability to Parliament (Fourth Report) (HC 422).

49 Everett, GBM (2017) The Royal Prerogative (House of Commons Library, Briefing Paper 03861), paras 26, 27.

50 Le Roux, N (2017) ‘Over-mighty executive: since 1997, Britain has been drifting towards elective dictatorship’, Democratic Audit UK.

51 Morris, M (1998) The British Monarchy and the French Revolution. Yale University Press, p49.

52 R (on the application of Miller and another) (Respondents) v Secretary of State for Exiting the European Union (Appellant) [2017] UKSC 5.

53 R (on the application of Miller and another) (Respondents) v Secretary of State for Exiting the European Union (Appellant) [2017] UKSC 5 [83].

54 Fredman, S (2017) ‘Miller: a vital reaffirmation of parliamentary sovereignty’, Oxford Human Rights Hub.

55 Namely Lord Reed, Lord Carnwath and Lord Hughes.

56 R (Miller) v The Prime Minister; Cherry v Advocate General for Scotland [2019] UKSC 41, [2020] AC 373.

57 Blitz, J and Dickie, M (2017) ‘Scotland fears farming and fishing Brexit power grab’, Financial Times.

58 Evans v Attorney General [2015] UKSC 21, [2015] AC 1782.

59 Elliott, M (2014) ‘What a (for now failed) attempt to curb judicial review tells us about the UK’s constitution’, Public Law for Everyone.

60 Ibid.

61 Elliott, M (2013) ‘Standing, judicial review and the rule of law: why we all have a “direct interest” in government according to law’, Public Law for Everyone.