Parliamentary sovereignty is the central organising principle of the UK constitution. It sits underneath every other Paper 2 essay topic (devolution, the judiciary, the Human Rights Act, the Lords). Despite that centrality, there has not been a 30-mark essay directly on parliamentary sovereignty since 2022. Four years is a long wait for the most important principle on the spec, so the topic is overdue.
Five recent events make a Q2(b) essay on parliamentary sovereignty very likely this summer. First, the Safety of Rwanda Act 2024 saw Parliament directly override a Supreme Court ruling by statute - the highest-profile Parliament-versus-courts moment in twenty years. Second, the Internal Market Act 2020 demonstrated Westminster's power to legislate over devolved objections from all three nations. Third, the EU (Withdrawal Agreement) Act 2020 completed Brexit and unwound the supranational arrangement Factortame (1990) had established. Fourth, Miller 1 (2017) confirmed the Sewel Convention is a political convention, not legally enforceable. Fifth, the 2025 examiner report praised answers that ran the parliamentary-sovereignty thread across multiple sub-topics rather than treating it as one of them. All five point to a 30-mark essay on this area.
This is a Section B 30-mark essay. Marks split roughly equally between AO1 (your knowledge of the Diceyan definition and the statutes that test it), AO2 (analysis of why each statute or case fits the line of argument), and AO3 (your judgement, which must be picked at the start and held to the end).
A V Dicey's The Law of the Constitution (1885) is still the textbook definition of parliamentary sovereignty. It has three rules.
Every example of "erosion" has to be measured against these three rules. Does the change actually stop Parliament making any law it wants? Or is the limit only political, conventional, or temporary? Almost every constraint the agree side will reach for fails this test once you push on it.
This side argues that since 1973 Parliament has been progressively wrapped in legal, political and conventional constraints that have weakened its supposed absolute authority. The evidence falls into five areas: EU membership and Factortame, devolution, the Human Rights Act, the rise of judicial review, and the political weight of referendums.
From the European Communities Act 1972 (effective 1 January 1973) until Brexit took full effect in January 2020, EU law had primacy over UK statute. In Factortame (1990) the House of Lords disapplied parts of the Merchant Shipping Act 1988 because it conflicted with EU law - the first time in modern history that a UK court had refused to enforce a UK statute. For 47 years, Diceyan sovereignty was qualified in a way it had not been before.
The Scotland Act 1998, Government of Wales Act 1998 and Northern Ireland Act 1998 created three devolved legislatures with primary legislative powers in their own competences. The Scotland Act 2016 went further, handing Holyrood full income-tax setting powers. The Sewel Convention says Westminster will not normally legislate on devolved matters without consent. The Wales Acts of 2014 and 2017 created a Welsh reserved-powers model. The cumulative effect is a constitution where Parliament now has to negotiate with three other elected legislatures on a long list of matters Westminster used to control alone.
The HRA incorporated ECHR rights into UK law from October 2000. UK courts can issue declarations of incompatibility against UK statutes. Belmarsh (2004) was the highest-profile early example, on indefinite detention of foreign nationals. The European Court of Human Rights in Strasbourg can find the UK in breach (Hirst v UK 2005 on prisoner voting). Although declarations of incompatibility do not strike down statutes, they create powerful political pressure on Parliament to respond.
Since the 1960s judicial review has expanded into a major check on executive decisions. Miller 1 (2017) forced the government to put the Article 50 notification to a parliamentary vote. Miller 2 / Cherry (2019) ruled the prorogation of Parliament unlawful. Although these rulings constrained the EXECUTIVE rather than Parliament itself, the agree side reads them as a steady judicialisation of areas that used to be purely political - and an implicit limit on what Parliament can authorise the executive to do.
The 1975 EEC referendum, 2011 AV referendum, 2014 Scottish referendum and 2016 EU referendum have established a convention that constitutional change of any significance requires a referendum mandate. The 2016 vote was advisory in law but treated as legally binding in political practice. The agree side argues that once "the people" have spoken in a referendum, Parliament is effectively bound - which is the opposite of Dicey's principle that no body can bind Parliament.
| Source of erosion | Year | What it shows |
|---|---|---|
| Factortame (EU primacy) | 1990 | UK court disapplied parts of a UK statute under EU law for 47 years |
| Scotland / Wales / NI Acts | 1998 | Three new elected legislatures with primary legislative power |
| HRA 1998 + Hirst v UK | 1998 / 2005 | Declaration of incompatibility regime; Strasbourg adverse findings |
| Miller 1 / Miller 2 | 2017 / 2019 | Judicial review reaching prerogative and prorogation |
| Referendums as binding | 1975-2016 | Brexit treated as legally binding despite being advisory in law |
This side argues that every supposed limit on Parliament has turned out to be removable by Parliament itself, and that recent events have actually demonstrated Parliament's last word over the courts, the devolved nations, and international treaties. The evidence falls into five areas: Brexit as the proof, the Safety of Rwanda Act, Miller 1 on Sewel, the Internal Market Act, and the HRA being repealable.
Brexit is the single most important fact in this debate. Parliament unilaterally exited a 47-year supranational arrangement that the agree side had treated as the clearest erosion of sovereignty. The EU (Withdrawal Agreement) Act 2020 reclaimed legal supremacy. The thing that had limited Parliament most was removed by Parliament when it chose to. No constitutional change in the last fifty years has so directly proved Dicey was right.
In November 2023 the Supreme Court ruled Rwanda was not a safe third country for asylum seekers. Parliament responded in April 2024 with the Safety of Rwanda Act, which declared Rwanda safe in primary legislation and disapplied parts of the HRA in Rwanda removal cases. The Supreme Court accepted the statute. This is the clearest modern proof that Parliament has the last word over the courts. When Parliament speaks clearly, the Court steps back.
In Miller 1 the Supreme Court ruled the Sewel Convention is a political convention, not legally enforceable. Westminster can legislate on devolved matters without consent whenever it chooses. The agree side reads devolution as eroding sovereignty; Miller 1 says the legal position is the opposite - the devolved settlements bind Westminster only as a matter of political convention, not as a matter of law.
The Internal Market Act 2020 was passed by Westminster over the objections of Holyrood, the Senedd and Stormont, all of which refused legislative consent. Westminster legislated anyway, to protect the UK single market post-Brexit. The Act is the clearest modern example of Westminster using its sovereign legislative power to override devolved objections on a major economic matter. Devolution looks like erosion but Westminster retains the legal tools to override it whenever it chooses.
The Human Rights Act 1998 is an ordinary Act of Parliament that any future Parliament can repeal or amend. The Truss government's Bill of Rights Bill (2022, withdrawn) and ongoing Conservative debate about ECHR withdrawal demonstrate that the HRA is just another statute. International treaties including the ECHR can be denounced by the UK at any time. Strasbourg cannot strike down a UK statute and never has. The HRA is a limit Parliament chose to place on itself, and a limit Parliament can remove.
| Event / Statute | Year | What it shows |
|---|---|---|
| EU (Withdrawal Agreement) Act | 2020 | Parliament unilaterally exited a 47-year supranational arrangement |
| Miller 1 on Sewel | 2017 | Sewel is a political convention, not legally enforceable |
| Internal Market Act 2020 | 2020 | Westminster overrode devolved objections of all three nations |
| Safety of Rwanda Act 2024 | 2024 | Parliament directly overrode Supreme Court ruling by statute |
| HRA is repealable | Ongoing | Bill of Rights Bill withdrawn 2023; HRA can be repealed by simple statute |
Edexcel mark schemes are clear: top-band answers commit to one of the two views and defend it the whole way through. Fence-sitting answers stay at Level 3.
For this question, the stronger side is the disagree side: parliamentary sovereignty has NOT been significantly eroded. Brexit is the clinching example - Parliament reclaimed legal supremacy from the EU when it chose to. The Safety of Rwanda Act 2024 confirms Parliament has the last word over UK courts. The Internal Market Act 2020 confirms Westminster can override devolved objections. Miller 1 (2017) confirmed Sewel is a political convention, not a legal limit. Devolution and the HRA look like erosion but both are removable by simple Act of Parliament. Every supposed constraint on Parliament has turned out to be removable by Parliament. The constraint is overwhelmingly political, not legal.
So back the disagree side. Use the agree side's evidence (Factortame, devolution, HRA, Miller 2, referendums) to build the counter-arguments, then knock them down by showing each constraint is reversible by simple statute or by the political will Parliament chooses to exercise.
The view in the question is wrong: parliamentary sovereignty has not been significantly eroded. Erosion is more apparent than real. Brexit removed the most-cited limit (EU primacy) by simple statute. The Safety of Rwanda Act 2024 shows Parliament's last word over the courts. The Internal Market Act 2020 shows Parliament's last word over the devolved nations. The HRA is just another statute. The constraint on Parliament is overwhelmingly political and conventional, not legal. The disagree side wins.