Learning Outcomes
This article explores parliamentary sovereignty and its limitations, including:
- Core elements of the doctrine of parliamentary sovereignty and the distinction between its legal scope and its practical, political operation
- The pre‑ and post‑Brexit position of EU law in the UK; the status and future of retained EU law/assimilated law; and the continuing domestic effect of the Withdrawal Agreement and the Windsor Framework for Northern Ireland
- Operation of the Human Rights Act 1998 through sections 2, 3, 4 and 6, the effect of a declaration of incompatibility, and the practical impact of section 3 interpretations
- Devolution as a constitutional settlement compatible with continuing UK parliamentary sovereignty, the Sewel Convention, the “permanence” provisions in Scotland and Wales, and policing of legislative competence
- Roles of judicial review, the rule of law and key judicial authorities (including Jackson, HS2, Unison and Evans) as potential—though not yet decisive—constraints on Parliament or executive action
- Principles of express and implied repeal, the special position of “constitutional statutes”, and “manner and form” arguments
- Application of these principles to SQE‑style problem scenarios
SQE1 Syllabus
For SQE1, you are required to understand the doctrine of parliamentary sovereignty and its limitations within the UK constitutional framework, with a focus on the following syllabus points:
- the definition and core features of parliamentary sovereignty (positive, negative and continuing aspects)
- EU law in the UK constitution: ECA 1972 and supremacy pre‑Brexit; retained EU law under the European Union (Withdrawal) Act 2018; the Retained EU Law (Revocation and Reform) Act 2023 and “assimilated law”; and the continuing domestic effect of the Withdrawal Agreement and the Windsor Framework
- the effect of the Human Rights Act 1998: section 3 interpretation duty; section 4 declarations of incompatibility; section 6 unlawful acts of public authorities; section 10 remedial orders
- the legal and political impact of devolution, legislative competence, “permanence” clauses, and the Sewel Convention’s non‑justiciability
- the role of the courts and the rule of law: access to courts, ouster clauses, and the principle that Parliament must use clear words to curtail fundamental rights
- the practical significance of international law in a dualist constitution
- constitutional statutes and implied repeal, and the “manner and form” debate
Test Your Knowledge
Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.
- What is the doctrine of parliamentary sovereignty, and what are its three core elements?
- How did EU law limit the sovereignty of Parliament before and after Brexit?
- What is the effect of a declaration of incompatibility under the Human Rights Act 1998?
- Can the UK Parliament legislate on devolved matters without the consent of devolved legislatures?
- In what circumstances have judges suggested that there may be limits to parliamentary sovereignty?
Introduction
The doctrine of parliamentary sovereignty is a central principle of the UK constitution. It means that Parliament can make or unmake any law, and no other body can override or set aside its legislation. However, in practice, Parliament’s legislative supremacy is subject to important legal and political limitations. These include the legacy and reshaping of EU law post‑Brexit, the Human Rights Act 1998, devolution, and judicially recognised constitutional principles such as the rule of law and access to the courts. Understanding how these constraints operate—and their limits—is essential for SQE1.
The Doctrine of Parliamentary Sovereignty
Parliamentary sovereignty, as classically defined by A.V. Dicey, means that Parliament has the right to make or repeal any law, cannot bind its successors, and no person or body can override or question the validity of its legislation. Parliamentary sovereignty has a positive aspect (Parliament may legislate on any subject), a negative aspect (no court may invalidate an Act), and a continuing aspect (no Parliament can entrench legislation to bind a future Parliament as to content). The doctrine coexists with common law principles that influence how legislation is interpreted: Parliament must use clear words if it wishes to curtail fundamental rights or access to courts.
Key Term: parliamentary sovereignty
The principle that Parliament has supreme legal authority to make or repeal any law, cannot bind future Parliaments, and its Acts cannot be set aside by any other body.Key Term: constitutional statute
A statute of fundamental constitutional importance, such as the Human Rights Act 1998 or the Scotland Act 1998, which courts may treat as immune from implied repeal.
Legal and Practical Limitations on Parliamentary Sovereignty
Despite its theoretical supremacy, Parliament’s power is limited in several ways. These limits are legal, political, and practical, and they vary in strength. Some are marketable as “soft” constraints (e.g. political conventions), while others affect how courts approach and apply legislation (e.g. the principle of legality or constitutional statutes).
EU Law and Retained EU Law
Before Brexit
During the UK’s membership of the European Communities/Union, EU law had supremacy over domestic law in areas of EU competence. This was achieved through the European Communities Act 1972 (ECA 1972), which made EU law part of domestic law and directed courts to interpret and apply UK legislation consistently with EU obligations.
Key Term: supremacy of EU law
The principle that EU law prevails over conflicting national law in areas of EU competence.
The domestic basis for supremacy was the ECA 1972, not the EU legal order alone. In Costa v ENEL, the CJEU articulated supremacy; UK courts gave effect to supremacy because Parliament authorised it via the ECA 1972.
Factortame and Parliamentary Sovereignty
In R v Secretary of State for Transport, ex parte Factortame Ltd (No 2) [1991], the House of Lords disapplied provisions of the Merchant Shipping Act 1988 that conflicted with directly effective EU law. Factortame showed that while the ECA 1972 remained in force, courts would set aside incompatible domestic legislation. In domestic terms, Parliament had “authorised” this outcome by enacting the ECA 1972 (and could reverse it by repealing that Act).
After Brexit
The European Union (Withdrawal) Act 2018 (EUWA 2018) repealed the ECA 1972 and created a new framework:
- It converted much EU law into domestic law at the end of the transition period (31 December 2020) as “retained EU law” (including EU-derived domestic legislation and direct EU legislation that was operative at that time).
- It preserved relevant rights under the Withdrawal Agreement and gave them direct effect in domestic law via section 7A EUWA 2018 (notably important for citizens’ rights and the Windsor Framework arrangements for Northern Ireland).
Originally, retained EU law carried a limited form of “supremacy” over pre‑exit domestic legislation and was informed by retained EU case law. However, this position altered significantly:
- The Retained EU Law (Revocation and Reform) Act 2023 (REUL Act 2023) re‑framed the regime from 1 January 2024:
- the general principle of supremacy of EU law was removed and references to EU law supremacy ceased to apply to domestic enactments saved into UK law;
- most EU general principles no longer apply as standalone causes of action;
- much of retained EU law is now treated as “assimilated law” within domestic categories;
- higher domestic courts have broadened powers and criteria to depart from retained EU case law.
The Withdrawal Agreement obligations remain directly effective through section 7A EUWA 2018, and the Windsor Framework continues to shape the application of EU-related rules in Northern Ireland. Thus, while the historic limited supremacy once attached to retained EU law has largely fallen away since 1 January 2024, treaty obligations incorporated by EUWA 2018 continue to bind as a matter of domestic law.
Key Term: retained EU law
EU law that was preserved in UK law after Brexit (now largely “assimilated law” following the REUL Act 2023), continuing to apply unless and until amended or repealed by Parliament; Withdrawal Agreement rights continue to have effect via EUWA 2018.
Worked Example 1.1
A UK regulation made in 2007 implemented an EU directive and conflicts with a 2010 Act of Parliament on the same topic. Post‑Brexit, which prevails?
Answer:
Prior to 1 January 2024, retained EU law could in some circumstances prevail over earlier pre‑exit legislation. Since the REUL Act 2023, the general EU‑law “supremacy” no longer applies domestically. The court will apply ordinary domestic principles: later primary legislation (2010 Act) prevails over earlier subordinate legislation (2007 regulation). If the conflict engages Withdrawal Agreement rights given domestic effect by EUWA 2018 s.7A, those rights continue to take precedence in domestic law.
The Human Rights Act 1998
The Human Rights Act 1998 (HRA) incorporates most rights in the European Convention on Human Rights (ECHR) into UK law. Courts must take into account relevant Strasbourg jurisprudence (section 2), interpret legislation, so far as possible, to be compatible with Convention rights (section 3), and can declare primary legislation incompatible (section 4) where a conforming interpretation is not possible. It is unlawful for public authorities to act incompatibly with Convention rights unless primary legislation compels them to do so (section 6); where compelled, the authority has a defence, and the incompatibility is addressed politically or legislatively, often using the fast‑track remedial order process (section 10).
Key Term: declaration of incompatibility
A formal statement by a higher court that a statute is incompatible with the ECHR, which does not invalidate the statute but signals to Parliament that amendment is needed.
Section 3 is powerful: in R v A (No 2) and Ghaidan v Godin‑Mendoza the House of Lords adopted strained but not textually contradictory readings to achieve compatibility. By contrast, where the statutory language cannot bear a Convention‑compatible meaning—R (Anderson) v Secretary of State for the Home Department and A v Secretary of State for the Home Department (the “Belmarsh” case)—courts make a declaration under section 4. Declarations do not strike down Acts, but political pressure typically leads to legislative change; the Government may use section 10 to amend quickly, subject to safeguards.
Courts continue to apply domestic constitutional principles alongside the HRA. In R (Unison) v Lord Chancellor, the Supreme Court struck down tribunal fees (secondary legislation) for obstructing access to justice, a fundamental constitutional principle; that case illustrates the rule of law’s practical bite.
Worked Example 1.2
Parliament enacts an Act that mandates a minister, not a court, to decide an offender’s minimum custodial term. Is this compatible with the HRA, and what can courts do?
Answer:
The provision likely breaches Article 6 (independent and impartial tribunal), as held in Anderson. A section 3 reinterpretation to transfer sentencing back to courts would contradict express statutory wording. The appropriate response is a section 4 declaration of incompatibility. The provision remains valid until Parliament amends it; the minister’s decisions made under compulsion of the Act will not render the minister liable under section 6 HRA.
Devolution
Devolution has created legislatures in Scotland, Wales, and Northern Ireland with power to legislate on devolved matters. They are not sovereign: each legislature’s competence is defined by its founding Act (Scotland Act 1998 and subsequent amendments; Government of Wales Act 2006; Northern Ireland Act 1998). The UK Parliament remains legally sovereign and can legislate on any matter, including devolved ones.
The Scotland Act 2016 and Wales Act 2017 include provisions recognising the “permanence” of their institutions and providing that they may only be abolished following a referendum in the territory. These clauses are constitutionally weighty and politically important, but they do not restrict the legal principle that an Act of the UK Parliament is supreme. The devolved institutions’ Acts are commonly treated as constitutional statutes, and therefore not subject to implied repeal.
The Sewel Convention provides that the UK Parliament “will not normally legislate with regard to devolved matters without the consent” of the relevant devolved legislature. In R (Miller) v Secretary of State for Exiting the EU [2017] the Supreme Court accepted that Sewel had been acknowledged in statute but remained a political, not legal, constraint and was not justiciable.
Legislative competence is policed by the courts: devolved Acts outside competence are “not law”. Competence questions may be referred to the UK Supreme Court. Devolved legislation must also comply with the ECHR and—with appropriate saving—may be affected by EU‑related obligations given domestic effect via EUWA 2018 (subject to REUL reforms). In 2022 the Supreme Court confirmed that a Scottish Independence Referendum Bill fell outside competence without UK consent since the Union and Parliament are reserved matters.
Key Term: Sewel Convention
The constitutional convention that the UK Parliament will not normally legislate on devolved matters without the consent of the relevant devolved legislature.
Worked Example 1.3
The UK Parliament passes an Act changing a health policy that is devolved to Scotland. Holyrood refuses a legislative consent motion (LCM). Is the UK law valid in Scotland?
Answer:
Yes. The Sewel Convention is a political constraint and not legally enforceable (Miller). The Act applies in Scotland as a matter of domestic law. Political consequences may follow, but courts will not invalidate the Act for lack of consent.
International Law
The UK is a dualist state. International treaties do not have domestic legal effect unless incorporated by Parliament. Courts may presume that Parliament legislates in accordance with international obligations and may interpret ambiguous provisions consistently with such obligations, but clear statutory language will prevail over inconsistent international law.
Classic authorities such as Mortensen v Peters and Cheney v Conn confirm that Acts of Parliament are supreme in domestic law even if inconsistent with international obligations. Recent controversies (e.g. legislative proposals affecting the Northern Ireland Protocol) illustrate the political and diplomatic consequences of breaching treaty commitments; domestically, however, a statute prevails unless constrained by other domestic constitutional rules.
The Role of the Courts and the Rule of Law
Courts do not strike down Acts of Parliament for violating constitutional principles, but judicial statements and decisions indicate powerful constraints on executive action and on secondary legislation, and they shape how statutes are read.
- In R (Jackson) v Attorney General [2005], several Law Lords suggested that extreme legislation undermining the rule of law—such as abolishing judicial review or basic democratic rights—might not be given effect by the courts. These remarks were obiter and have not been tested, but they signal constitutional fundamentals.
- In R (HS2 Action Alliance) v Secretary of State for Transport [2014], the Supreme Court treated the Bill of Rights and aspects of parliamentary procedure as constitutional, resisting arguments that would allow EU law to require detailed interrogation of parliamentary processes.
- In R (Unison) v Lord Chancellor [2017], the Supreme Court held that fees that prevented effective access to tribunals were unlawful, affirming access to justice as a constitutional principle.
- In R (Evans) v Attorney General [2015], the Supreme Court quashed a ministerial “veto” seeking to override a judicial decision under the Freedom of Information Act, emphasising the separation of powers and the rule of law.
Courts also resist broad “ouster clauses” that purport to exclude judicial review. In Anisminic and later in R (Privacy International) v Investigatory Powers Tribunal [2019], the Supreme Court adopted a narrow reading of ousters to protect the supervisory jurisdiction of the High Court. The “principle of legality” means that Parliament must use clear words to curtail fundamental rights or access to courts; general or ambiguous language will not suffice.
Key Term: rule of law
The principle that all persons and authorities, including Parliament, are subject to and accountable under the law.Key Term: judicial review
The process by which courts supervise the legality of actions or decisions by public bodies, including the exercise of statutory and prerogative powers.
Worked Example 1.4
Parliament enacts an Act stating “decisions of X Tribunal shall be final, and no decision shall be questioned in any court.” Can the High Court still judicially review X Tribunal?
Answer:
Courts approach ouster clauses narrowly. Following Anisminic and Privacy International, broad ouster language is unlikely to exclude review for legal error or jurisdictional defects unless Parliament uses exceptionally clear and targeted wording. The High Court will likely retain a supervisory role.
Express and Implied Repeal
Parliament cannot bind its successors as to the content of future legislation. Any Act can be repealed expressly or, where it is irreconcilably inconsistent with later legislation, by implication. In Ellen Street Estates the Court of Appeal restated that no Parliament can prevent implied repeal of its legislation by a later Act dealing with the same subject matter.
However, courts recognise “constitutional statutes” that are not susceptible to implied repeal. In Thoburn v Sunderland City Council, Laws LJ identified statutes such as the ECA 1972, the HRA 1998 and the devolution Acts as constitutional statutes: they condition the legal relationship between citizen and state or change fundamental rights and require express words for repeal or amendment. The Supreme Court has echoed this approach, for example in HS2 and H v Lord Advocate.
Worked Example 1.5
A new Act of Parliament is passed that conflicts with an earlier constitutional statute, but does not mention it. Is the earlier Act still in force?
Answer:
Courts may treat the earlier constitutional statute as immune from implied repeal. Only express words in the new Act will repeal it.
Political and Practical Constraints
Beyond firm legal rules, politics shapes what Parliament will do. Major constitutional measures—such as repealing the HRA 1998, dismantling devolution settlements, or legislating in obvious breach of international law—are legally possible but politically costly. The “permanence” provisions in the Scotland and Wales Acts and the referendum requirement for Northern Ireland’s status demonstrate high political thresholds. International relationships and market reactions impose further discipline.
Worked Example 1.6
Parliament passes an Act that breaches an international treaty. What is the effect in UK law?
Answer:
The Act is valid in domestic law, but the UK may face international consequences. Courts may interpret the Act to be consistent with the treaty if possible, but cannot set it aside solely for breach of international law.
The "Manner and Form" Debate
A long‑standing question is whether Parliament can entrench procedures (manner and form) for future legislation rather than entrenching substantive content. In Commonwealth cases such as AG (NSW) v Trethowan, legislatures created by superior instruments were required to follow stipulated “manner and form” requirements (for example, a referendum) when altering constitutional arrangements. The UK situation is different because the UK Parliament is sovereign and not a subordinate legislature, but the debate persists.
Practical illustrations in the UK include provisions requiring referendums for particular constitutional changes (e.g. section 1 Northern Ireland Act 1998) or recognising “permanence” (e.g. Scotland Act 2016). Legally, a future sovereign Parliament could repeal such provisions using ordinary legislative processes; politically, it is difficult to foresee this happening without following the stipulated procedure.
Judicial Warnings and the Rule of Law
While Parliament is legally supreme, some judges have warned that legislation abolishing judicial review, dismantling basic democratic protections, or removing access to justice might not be given effect. Jackson contains the best‑known statements. Courts have never refused to apply an Act on such grounds; the warnings function as constitutional signposts. In everyday practice, the rule of law constrains executive action, shapes interpretation, and scrutinises secondary legislation.
Exam Warning
The courts have never struck down an Act of Parliament for violating constitutional principles. However, you may be asked in the SQE1 about judicial statements suggesting possible limits to sovereignty in extreme cases.
Key Point Checklist
This article has covered the following key knowledge points:
- Parliamentary sovereignty means Parliament can make or repeal any law, cannot bind future Parliaments, and its Acts cannot be set aside by other bodies.
- During EU membership, domestic courts gave effect to EU law supremacy through the ECA 1972; post‑Brexit, EUWA 2018 created retained EU law, which the REUL Act 2023 has re‑framed as “assimilated law” without general EU‑law supremacy; Withdrawal Agreement rights continue to have direct effect via EUWA 2018 s.7A.
- The Human Rights Act 1998 requires courts to interpret legislation compatibly with the ECHR where possible (s.3) and allows declarations of incompatibility (s.4); public authorities must act compatibly with the ECHR unless compelled by primary legislation (s.6).
- Devolution grants law‑making powers within defined competences, subject to the ECHR and other constraints; the UK Parliament remains legally sovereign. The Sewel Convention is a political, not legal, constraint.
- International law does not override Acts of Parliament in domestic law; courts may interpret statutes consistently with international obligations where possible.
- Courts recognise constitutional statutes that cannot be impliedly repealed and use the principle of legality to require clear words for curtailing fundamental rights or access to the courts.
- Judicial decisions emphasise access to justice and limited tolerance for ouster clauses. Obiter statements in Jackson suggest possible ultimate limits in an extreme case, but no Act has been struck down on that basis.
Key Terms and Concepts
- parliamentary sovereignty
- constitutional statute
- supremacy of EU law
- retained EU law
- declaration of incompatibility
- Sewel Convention
- rule of law
- judicial review