1. Understanding Parliamentary Sovereignty
In this chapter we focus on Parliament and Parliamentary Sovereignty, considering the functions and procedures of the UK Parliament. We begin with the classical doctrine of parliamentary supremacy and the Enrolled Act rule, before turning to the domestic and European limitations said to qualify it.
(i) statute may override international law;
(ii) statute may override constitutional conventions;
(iii) statute may alter the Constitution;
(iv) statute may operate retrospectively;
(v) statute may abolish or curtail aspects of the Royal Prerogative.
1.1.1 Limitations on the Supremacy of Parliament
It may be argued that parliamentary supremacy is no longer regarded as absolute and is subject to certain limitations, which are usually categorised as 'domestic' and 'European'.
1.1.1.1 Domestic Limitations
The Acts of Union may limit the absolute power of Parliament. The Acts of Union clearly declared that the separate Scottish legal system and the Church of Scotland would be preserved 'forever'. As a result, Parliament was said to be 'born unfree', because its power is limited by the terms of the Acts of Union and it cannot legislate to override their provisions: for example, Parliament cannot pass Acts to change the Scottish legal system and the Church of Scotland. The terms of the Acts of Union were bound to the Westminster Parliament (MacCormick v Lord Advocate (1953)).
Scottish devolution limits the power of Parliament. Acts of Parliament have devolved power to new legislative bodies in Northern Ireland, Scotland and Wales, with the Scottish Parliament generally having greater legislative power than the other two bodies. Under the Scotland Act 1998, the Scottish Parliament and Executive were established, with legislative power in certain areas such as health, education and legal affairs. The Scotland Act 1998 was amended by the Scotland Act 2016, which increased the range of devolved powers, including income tax varying powers. The Scotland Act 2016 declares that the Scottish Parliament and Executive are a permanent part of the UK constitutional arrangements; they cannot be abolished unless the Scottish people vote for this in a referendum, and without the consent of the Scottish Parliament the UK Parliament will not legislate with regard to devolved matters.
Acts of independence make some statutes practically impossible to repeal without great political, economic and social unrest. Parliament granted independence to former British colonies by enacting various Acts; it would be impossible for Parliament to reverse and repeal such legislation. For example, it is almost impossible to reassert Westminster's right to legislate for Scotland because doing so would invoke a political crisis. Such legislation is particularly difficult for Parliament to repeal for political reasons.
Limits on the doctrine of implied repeal. Although Parliament can expressly or impliedly repeal the contents of an earlier or later Act, there are limits on implied repeal. Generally there are two types of statute: 'ordinary' and 'constitutional'. According to Thoburn v Sunderland City Council, Laws LJ stated that a constitutional statute — especially one concerning the legal relationship between citizen and state, and fundamental constitutional rights — cannot be impliedly repealed. In other words, ordinary statutes may be impliedly repealed, while constitutional statutes may not.
The 'manner and form' debate (entrenchment). Manner-and-form, or entrenchment, theory may make an Act difficult to pass, amend or repeal by imposing procedural requirements in the legislation. Under the Parliament Acts 1911 and 1949, Parliament removed the requirement for legislation to be passed by the House of Lords, making it 'easier' to legislate. It has been argued that, if Parliament can make it 'easier' to legislate, it could also make it 'harder' for a future Parliament to legislate — so an earlier Parliament might impose a complex procedure that a future Parliament must follow. Although the position is unclear and there is no authoritative answer, the courts have stated that entrenchment of legislation is possible (A-G for NSW v Trethowan).
The rule of law. There are disputes about the hierarchy between parliamentary supremacy and the rule of law. According to Dicey, the supremacy of Parliament — not the rule of law — is the prime constitutional principle. However, in R (Jackson) v A-G, some of their Lordships suggested (obiter) that parliamentary supremacy was a construct of the common law and that, in extreme circumstances, the courts might decline to recognise an Act that was contrary to the rule of law. For example, if Parliament enacted legislation to abolish judicial review, the courts might refuse to uphold the legislation.
Henry VIII powers. Henry VIII powers grant law-making power to the Government, permitting the relevant government minister to modify some primary legislation or repeal the relevant statute. Government ministers also have important law-making powers because Parliament has limited opportunities to scrutinise delegated legislation. This contradicts the basic principle of parliamentary sovereignty, because it enables ministers to modify laws.
1.1.1.2 European Limitations
In addition to domestic restrictions, there are European restrictions. As a former member state, the UK had to ensure the fulfilment of EU obligations under various treaties — for example the Treaty on the Functioning of the European Union (TFEU), the Treaty of Amsterdam and the Treaty of Nice. Article 288 TFEU states that member states are required to implement directives in their national law. A breach of these treaties is a breach of international law and would lead to state liability.
The doctrine of parliamentary supremacy was significantly influenced by the European Communities Act 1972, by which Parliament gave effect to the EU Treaties in domestic law. Section 2(4) of the ECA 1972 is the most important section: it provides that 'any enactment passed or to be passed... shall be construed and have effect subject to the foregoing provisions of this section'. The domestic courts interpreted two limbs of s.2(4).
First limb — 'shall be construed': the courts must read and interpret UK law to comply with EU law. With reference to earlier cases such as Pickstone v Freemans, Litster v Forth Dry Dock and Webb v EMO, the UK courts were prepared to interpret UK legislation to implement the relevant directive as far as it is possible.
Second limb — 'shall have effect': the cases of Factortame and ex p EOC had an important effect on parliamentary supremacy. Where the operation of an Act of Parliament was incompatible with directly effective EU law, the House of Lords (following the ruling of the ECJ on the reference in Factortame (No.2)) held that EU law must have priority over domestic legislation and that the conflicting provisions of the Act must be disapplied.
Although Factortame indicated that EU law took priority over inconsistent domestic legislation while the UK remained a member state, there was nothing to prevent Parliament from expressly repealing the provisions of EU law — so the ECA 1972 could be expressly repealed, which confirmed that EU membership never displaced parliamentary sovereignty in the ultimate sense. The European Union (Withdrawal) Act 2018 repealed the ECA 1972 on 'exit day' (31 January 2020). For a time, much EU law continued to apply as 'retained EU law', but the Retained EU Law (Revocation and Reform) Act 2023 abolished the supremacy of EU law in domestic law with effect from 1 January 2024 and renamed retained EU law as 'assimilated law'. EU limitations on parliamentary sovereignty are therefore now of historical importance only.
The Human Rights Act 1998 (HRA) also has a significant effect on parliamentary supremacy. Individuals can claim a breach of Convention rights before a domestic court. The Government chose to incorporate the Convention into UK law by a 'weak' method, because it worried that the judiciary would otherwise have power to strike down Acts of Parliament and deprive them of legal effect. Under s.2 HRA 1998, the UK courts must take into account (but are not bound by) judgments of the European Court of Human Rights (ECtHR). The HRA nonetheless has an important impact on parliamentary supremacy, particularly in relation to s.3 and s.4.
For example, in R (Anderson) v Secretary of State for the Home Department, the court made a declaration of incompatibility because a compatible interpretation would have been expressly contrary to the wording of the statute; the offending legislation was repealed within three months of the decision. Although Parliament could amend and expressly repeal the HRA 1998, its withdrawal may cause political and social unrest because the statute grants basic civil rights and liberties to citizens, so Parliament is unlikely to repeal it. Indeed, the Conservative party pledged in its 2015 election to repeal and replace it with a UK Bill of Rights and Responsibilities, but later plans were to keep the HRA 1998 and 'update' it.
| Domestic limitations | European limitations |
|---|---|
| The Acts of Union | Membership of the European Union |
| Devolution | Impact of the Human Rights Act 1998 |
| Acts of independence | Express repeal of the ECA 1972 or the Human Rights Act 1998 |
| Limits on the doctrine of implied repeal | — |
| The 'manner and form' debate | — |
| The rule of law | — |
| Henry VIII powers | — |
2. The Role of Parliament
Parliament is the legislative body of government. Its role may be described as formally enacting the Government's legislative proposals rather than making the law itself. We consider here the four functions of Parliament, its composition (the two Houses), the legislative process, and the different types of bill.
(i) providing the personnel of government;
(ii) 'legitimising' the actions taken by the Government;
(iii) overseeing the Government via hearings and inquiries;
(iv) authorising the funding necessary for the Government to carry out its statutory duties and legislative proposals.
1.2.1 The Composition of Parliament
The UK Parliament comprises two separate Houses: the House of Commons and the House of Lords. Their work is similar — making laws (legislation), checking the work of the Government (scrutiny), and debating current issues. Generally, the decisions made in one House must be approved by the other, so the two-chamber system acts as a check and balance for both Houses.
The House of Commons is a representative body whose membership is elected. There are currently 650 Members of Parliament. Members of the Commons (MPs) debate the big political issues of the day and proposals for new laws. The House of Commons is also responsible for granting money to the Government through approving Bills that raise taxes.
The House of Lords is not elected and is not a representative body. Most members are life peers appointed under the Life Peerages Act 1958. Following the House of Lords (Hereditary Peers) Act 2026, which removed the right of the remaining hereditary peers to sit and vote, the current membership comprises:
The Lords Temporal — life peers created under the Life Peerages Act 1958 (the hereditary peers were excluded by the House of Lords (Hereditary Peers) Act 2026); and
The Lords Spiritual — 26 bishops and archbishops of the Church of England.
The House of Lords spends time examining and perfecting the details of each law. The Lords share the task of making and shaping laws and checking and challenging the work of the Government.
| The House of Commons | The House of Lords |
|---|---|
| Publicly elected | Not publicly elected |
| There are currently 650 Members of Parliament | Most members are life peers appointed under the Life Peerages Act 1958 |
| Debates the big political issues | The remaining hereditary peers were excluded by the House of Lords (Hereditary Peers) Act 2026 |
| Proposes new laws | 26 bishops and archbishops of the Church of England (the Lords Spiritual) |
| Responsible for granting money to the Government through approving Bills that raise taxes | Examines and perfects the details of each law |
| — | Shares the task of making and shaping laws and checking and challenging the work of the Government |
1.2.2 The Legislative Process
To become an Act of Parliament, a bill must usually be passed by both Houses, and in each House there is a long and complex process. All bills must go through the following stages.
First reading — purely formal: the title of the bill is read out, and it is then printed and published.
Second reading — the main debate takes place in the House of Commons on the general principles of the bill.
Committee stage — a detailed examination of each clause is undertaken by a general committee of between 16 and 50 members appointed by the Committee of Selection. Amendments may be made. Important bills (for example, bills of constitutional significance or concerned with authorising government expenditure), or uncontroversial bills requiring little discussion, may be referred to the 'Committee of the Whole House'.
Report stage — necessary if amendments were made at the Committee stage. The House votes on any amendments and each part of the bill is considered in light of the amendments or additions. If there were no amendments at the Committee stage, there will be no Report stage and the bill goes on to the Third reading.
Third reading — consideration of the bill as amended; normally the debate is brief and only verbal amendments may be made. This is the final opportunity to vote on the bill (often, MPs do not).
Once the bill has completed the Third reading in the House of Commons, it is passed to the House of Lords to go through the same five stages. If a bill originates in the House of Lords, it goes to the House of Commons and undergoes the same five procedures. This passing of the bill between Houses is repeated until both Houses agree on the text of the bill.
1.2.3 Public Bills
Public bills alter the general law. There are two forms of public bill.
(a) Government bills — bills submitted to Parliament as part of the Government's legislative programme. They are usually listed in the Queen's Speech (King's Speech) at the start of the parliamentary session and constitute the majority of public bills. The relevant government department decides on the detailed content.
(b) Private member's bills — bills introduced by MPs or Lords who are not government ministers. Although very few ever become law, due to lack of parliamentary time, they sometimes create significant publicity about an issue and can indirectly influence the Government's legislative proposals.
1.2.4 Private Bills
Private bills relate to matters of individual, corporate or local interests and affect the law applicable to particular persons and/or organisations.
① Four functions — providing personnel, legitimising Government action, overseeing the Government, and authorising funding.
② Composition — the elected House of Commons (650 MPs) and the unelected House of Lords (life peers under the Life Peerages Act 1958 and 26 Lords Spiritual; the hereditary peers were excluded by the House of Lords (Hereditary Peers) Act 2026); the Commons has greater democratic legitimacy.
③ Legislative process — First reading → Second reading → Committee stage → Report stage → Third reading → (between Houses) → Royal Assent.
④ Types of bill — public bills (Government bills; private member's bills) alter the general law; private bills affect particular persons or organisations.
3. Key Notes (Chapter Summary)
The following summary table consolidates every key concept, case and reference examined in this chapter. Treat it as a revision checklist — you should be able to define each item from memory and cite the leading authority.
| Key Items | Concepts | Cases / References |
|---|---|---|
| Parliamentary Sovereignty | A.V. Dicey's classical definition emphasises that Parliament is the supreme law-making body with no legal restraints on its powers. | A.V. Dicey; Pickin v BRB |
| Enrolled Act Rule | UK courts cannot challenge the validity of an Act of Parliament once it has received Royal Assent. | Pickin v BRB |
| Limitations on Sovereignty | Parliamentary sovereignty is subject to domestic and European limitations. | MacCormick v Lord Advocate; Scotland Act 1998; Scotland Act 2016 |
| Domestic Limitations | Includes the Acts of Union, Scottish devolution, Acts of independence, and limits on the doctrine of implied repeal. | Acts of Union; Scotland Act 1998; Thoburn v Sunderland City Council; A-G for NSW v Trethowan |
| European Limitations | EU membership (now historical, following Brexit) and the Human Rights Act 1998 imposed limitations on parliamentary sovereignty. | European Communities Act 1972; Factortame; European Union (Withdrawal) Act 2018; Retained EU Law (Revocation and Reform) Act 2023 |
| Role of Parliament | The legislative body of government has four main functions: providing personnel, legitimising actions, overseeing the Government, and authorising funding. | — |
| Composition of Parliament | Consists of the House of Commons and the House of Lords, each with distinct roles and powers. | Life Peerages Act 1958 |
| Legislative Process | A bill must go through several stages in both Houses to become an Act of Parliament. | Parliament Acts 1911 and 1949 |
| Types of Bills | Public bills alter the general law (Government bills or private member's bills); private bills relate to individual, corporate or local interests. | Queen's Speech (King's Speech) |
| Henry VIII Powers | Allow government ministers to modify or even repeal primary legislation, which runs counter to the principle of parliamentary sovereignty. | — |
| Rule of Law v Parliamentary Supremacy | There are debates about the hierarchy between parliamentary supremacy and the rule of law; some argue the rule of law could limit what Parliament can legislate. | R (Jackson) v A-G |
| Human Rights Act 1998 | Significant impact on parliamentary supremacy, especially s.3 (compatible interpretation) and s.4 (declaration of incompatibility). | Human Rights Act 1998; R v A (No.2); Ghaidan v Godin-Mendoza; R (Anderson) v Secretary of State for the Home Department |
4. MCQ Practice — SQE-Style Questions
Each of the following questions mirrors the style and difficulty of the SQE1 FLK1 single best answer questions. Attempt each question closed-book, write down your answer, then turn to the answer key. The answer key explains why each option is correct or incorrect — read every explanation in full.
A. Providing the personnel of the Government.
B. 'Legitimising' the actions taken by the Government.
C. Raising public awareness of the legislative process.
D. Overseeing the Government via hearings and inquiries.
E. Authorising the funding necessary for the Government to carry out its statutory duties and legislative proposals.
Answer & explanation
C is correct (it is the option that is NOT a function) — Parliament is a legislative body of government and generally has four functions: providing the personnel of the Government; 'legitimising' the actions taken by the Government; overseeing the Government via hearings and inquiries; and authorising the funding necessary for the Government. 'Raising public awareness of the legislative process' is not one of these recognised functions.
A is incorrect — providing the personnel of government is a recognised function.
B is incorrect — 'legitimising' the Government's actions is a recognised function.
D is incorrect — overseeing the Government via hearings and inquiries is a recognised function.
E is incorrect — authorising funding is a recognised function. (See Section 1.2.)
A. Report stage.
B. Committee stage.
C. Passed to the other House.
D. Third reading.
E. Royal Assent.
Answer & explanation
E is correct — once Royal Assent is received, a bill becomes law and is referred to as an 'Act of Parliament'. The Act may suspend its 'commencement' until some future date, which may be determined by delegated legislation made under the Act.
A is incorrect — the Report stage precedes the Third reading and is only needed where amendments were made at the Committee stage.
B is incorrect — the Committee stage is an early stage of detailed scrutiny.
C is incorrect — passing to the other House occurs after the Third reading but before Royal Assent.
D is incorrect — the Third reading is the final opportunity to vote, but it is not the final stage of the process. (See Section 1.2.2.)
A. Parliament is legally unlimited in its law-making authority.
B. Parliament is politically and legally unlimited in its law-making authority.
C. Parliament comprises the House of Commons, the House of Lords and the Monarch.
D. Parliamentary supremacy is subject to 'domestic' and 'European' limitations.
E. Everyone, including the Government, must act according to the law.
Answer & explanation
A is correct — A.V. Dicey provided the classical definition of parliamentary supremacy: there is no legal restraint upon Parliament's law-making powers; no other person or body may question the validity of primary legislation; and Parliament cannot bind its successors. He believed Parliament is the supreme law-making body.
B is incorrect — Dicey's theory addresses legal authority; it does not assert that Parliament is politically unlimited (political restraints exist).
C is incorrect — this describes the composition of Parliament (the Crown in Parliament), not Dicey's theory of sovereignty.
D is incorrect — the domestic and European limitations are arguments that qualify sovereignty; they are not Dicey's own theory.
E is incorrect — this describes the rule of law, a separate constitutional principle. (See Section 1.1.)
5. Separation of Powers and the Rule of Law
The SRA expressly tests 'Legitimacy, separation of powers and the rule of law' as a discrete heading within Constitutional and Administrative Law, and the September 2026 changes confirm that it remains examinable. These two doctrines are the foundational principles that explain why the institutions studied in this subject behave as they do. Parliamentary sovereignty (the previous section) tells us who makes law; the separation of powers tells us how state power is divided so that no single branch becomes too powerful; and the rule of law tells us that all power — including the power of Parliament and the Crown — must be exercised according to law and not arbitrarily. Although the United Kingdom has no single codified constitution, both doctrines are woven through statute, common law and convention, and they underpin every topic in this subject: constitutional conventions, the prerogative, parliamentary privilege, judicial review and the Human Rights Act 1998. This section explains both doctrines, their leading authorities, and how they interrelate with sovereignty.
Classical constitutional theory, associated with the French jurist Montesquieu, divides the functions of the state into three branches: the legislature (which makes law), the executive (which proposes policy and implements/enforces law) and the judiciary (which interprets and applies the law and resolves disputes). The theory of the separation of powers holds that, to protect liberty, these three functions should so far as possible be exercised by different persons or bodies, each acting as a check on the others. Where power is concentrated in a single set of hands, there is a danger of tyranny.
| Branch | Core function | Principal UK bodies/personnel |
|---|---|---|
| Legislature | Makes and unmakes law (primary legislation) | The King-in-Parliament: the House of Commons, the House of Lords and the monarch (Royal Assent); the devolved legislatures within their competence |
| Executive | Formulates policy; implements and enforces the law; conducts government | The monarch (formally), the Prime Minister and Cabinet, government ministers, the civil service, the police and armed forces, and local authorities |
| Judiciary | Interprets and applies the law; resolves disputes; reviews the legality of executive action | The judges of the courts and tribunals, headed by the Supreme Court and the Lord Chief Justice |
The UK does not have a strict, formal separation of powers. There are significant overlaps between the branches — most obviously between the legislature and the executive. Under the Westminster system of responsible government, the executive (the Government) is drawn from and sits within Parliament: by convention the Prime Minister and most ministers must be members of one of the two Houses, and the Government remains in office only so long as it commands the confidence of the House of Commons. For this reason the constitutional scholar Walter Bagehot described the 'efficient secret' of the constitution as the fusion of the executive and legislative branches, rather than their separation.
Legislature / Executive — ministers are members of Parliament; the Government controls most of the parliamentary timetable; and ministers exercise delegated legislative power through statutory instruments (a function that is legislative in substance but executive in form).
Executive / Judiciary — historically the Lord Chancellor sat in all three branches; some tribunals and inquiries perform adjudicative functions within the executive; and the Attorney General is both a government minister and a senior law officer.
Legislature / Judiciary — until 2009 the Appellate Committee of the House of Lords (the 'Law Lords') was the highest court yet sat within the legislature; senior judges may still sit in the House of Lords as crossbench peers (though they no longer adjudicate there).
Although the branches overlap, the independence of the judiciary is fiercely protected. Senior judges enjoy security of tenure (they hold office 'during good behaviour' and a senior judge may be removed only on an address presented to the monarch by both Houses of Parliament), their salaries are charged on the Consolidated Fund (so they are not subject to annual political vote), and their conduct in office is protected by the sub judice rule and by judicial immunity. In turn, the judiciary checks the executive through judicial review (Chapter 8) and checks Parliament's delegated legislation, while Parliament checks the executive through ministerial accountability (Chapter 2) and the executive checks the legislature through control of the legislative agenda.
The rule of law is the principle that everyone — including the government — is subject to and accountable under the law, and that legal disputes are resolved by an independent judiciary applying known, general rules rather than by arbitrary power. It is expressly recognised in statute: s. 1 of the Constitutional Reform Act 2005 provides that the Act does not adversely affect 'the existing constitutional principle of the rule of law'. The doctrine has both a formal/procedural dimension (concerned with how law is made and applied) and, in its broader conceptions, a substantive dimension (concerned with the content of the law and the protection of fundamental rights).
The classic exposition is by A.V. Dicey in An Introduction to the Study of the Law of the Constitution (1885), who identified three meanings of the rule of law. Dicey's account remains a standard SQE reference point, although it has been criticised as incomplete (it says little about the content of the law and is in tension with the breadth of modern discretionary and prerogative power).
No punishment except for a breach of law — no one may be punished or made to suffer in body or goods except for a distinct breach of law established before the ordinary courts; this is the principle against arbitrary power.
Equality before the law — every person, whatever their rank or condition, is subject to the ordinary law and to the jurisdiction of the ordinary courts; officials enjoy no special immunity from the general law.
The constitution is the result of the ordinary law — in the UK, individual rights (such as personal liberty) are the product of judicial decisions in particular cases, rather than being derived from an abstract, codified bill of rights.
The most influential modern restatement is by Lord Bingham in The Rule of Law (2010), where he broke the principle down into eight sub-rules. Lord Bingham's account is broader than Dicey's because it includes the protection of fundamental human rights and compliance with international law, reflecting a substantive conception of the rule of law.
The law must be accessible and so far as possible intelligible, clear and predictable;
Questions of legal right and liability should ordinarily be resolved by application of the law and not the exercise of discretion;
The law should apply equally to all, save where objective differences justify differentiation;
Ministers and public officers must exercise their powers in good faith, fairly, for the purpose for which they were conferred, without exceeding the limits of those powers and not unreasonably (the foundation of judicial review);
The law must afford adequate protection of fundamental human rights;
Means must be provided for resolving, without prohibitive cost or inordinate delay, bona fide civil disputes (access to justice);
Adjudicative procedures provided by the state should be fair (a fair trial before an independent court);
The state must comply with its obligations in international law.
There is a potential tension between parliamentary sovereignty (Parliament may make or unmake any law and the courts may not strike down an Act) and the rule of law (which suggests that law should protect fundamental rights). The orthodox position is that sovereignty prevails: a court faced with a clear Act of Parliament must apply it, even if it considers it contrary to fundamental rights (the most the courts can do is issue a declaration of incompatibility under the HRA 1998, which does not invalidate the statute). However, the courts use the rule of law as a powerful interpretive presumption: they will read statutes, where the words allow, as not intending to oust the jurisdiction of the courts, remove access to justice, or interfere with fundamental rights without the clearest possible language (the principle of legality, R v Secretary of State for the Home Department, ex p Simms [2000] 2 AC 115). In obiter remarks in R (Jackson) v Attorney General [2005] UKHL 56, some Law Lords suggested that the rule of law might place ultimate limits even on parliamentary sovereignty, but this remains controversial and is not the orthodox position.