The story of how the UK shared sovereignty with the European Union, left it, and is still working out where sovereignty actually sits. The single most likely sovereignty-question topic in Paper 2 and the topic that crosses into the judiciary, parliament, and executive sections.
For 47 years the UK was a member of the European Union, and during that time it pooled some of its sovereignty with the other member states. UK law was subordinate to EU law in the areas the EU was responsible for (trade, environment, economic regulation, some rights). The Factortame case in 1990 made this concrete - a UK Act of Parliament was overruled by the European Court of Justice. The 2016 referendum and the Brexit process that followed reversed this arrangement. Parliament regained its legal sovereignty - but the question of where sovereignty really sits in the UK is more complicated than "we got it back". This walk-through covers what was pooled, what was reclaimed, what remains, and how all of this turns up in a Paper 2 sovereignty essay.
The bedrock concept. If this is solid, the rest of the topic stacks on top.
Parliamentary sovereignty is the constitutional rule that Parliament can make or unmake any law, that no Parliament can bind a future Parliament, and that no body above Parliament can overrule it. A V Dicey's nineteenth-century statement of the rule is still the textbook formulation.
You need to separate two senses of sovereignty in the exam.
Legal sovereignty is the theoretical power - what the constitution says can be done. Parliament has legal sovereignty: it can pass any Act it wants.
Political sovereignty is the reality of power - what actually gets decided and by whom. In practice the government dominates Parliament when it has a majority; the courts shape law through interpretation; the public sets limits through elections and referendums; and from 1973 to 2020 EU institutions had a real say.
Scroll - the framework that defined the UK-EU relationship from 1973 to 2020.
The UK joined the European Economic Community in 1973 under the European Communities Act 1972. Membership meant pooled sovereignty - decisions on trade, the environment, economic regulation, and some rights were made collectively at EU level rather than purely by Westminster. Two big treaties deepened this arrangement: Maastricht 1992 (created the European Union, expanded competences) and Lisbon 2007/9 (further integration, more qualified majority voting). The deal at the centre of the Single Market was the Four Freedoms - the things that had to be able to move freely across EU borders.
Pooled sovereignty was the deal: the UK accepted EU rules across a range of areas in exchange for access to the Single Market built around the Four Freedoms (goods, people, services, capital). Scroll through the elements.
European Communities Act 1972 was the original UK statute that brought EU law into the UK system. Maastricht Treaty 1992 created the European Union from what had been the European Economic Community; expanded the EU's policy reach beyond trade into citizenship, foreign policy, and justice. Lisbon Treaty 2007/9 further deepened integration - more qualified majority voting on the Council, stronger Parliament, the legal personality of the EU. These treaties are the formal legal vehicles for the deepening of pooled sovereignty.
The Single Market was built on four freedoms of movement across EU borders. Goods - frictionless trade without customs checks. People - freedom of movement; EU citizens could live and work in any member state. Services - service businesses could operate across borders. Capital - money could be invested across borders without restriction. The Four Freedoms allowed frictionless trade but limited domestic control - which became the central Brexit argument, particularly on freedom of movement for people.
The EU evolved in two directions simultaneously. Widening: more member states joined - the original 6 grew to 28 (briefly), then 27 after Brexit. The 2004 enlargement that brought in Poland and other former Eastern Bloc states is politically significant because it triggered substantial freedom-of-movement migration to the UK. Deepening: more policy areas brought under EU competence - environment, social policy, justice, common foreign and security policy. The Lisbon Treaty 2007/9 was the most significant deepening event before Brexit.
Five institutions ran the EU. Two were supranational (they exist above the member states and pursue an EU-wide agenda). Two were intergovernmental (they are composed of representatives of the member states). One is partly each. The European Commission is supranational and proposes legislation. The European Council is intergovernmental (heads of government). The Council of the European Union is intergovernmental (ministers). The European Parliament is supranational and directly elected. The European Court of Justice is supranational and enforces EU law. The figure beside you holds the institutions; the next part covers them in detail.
Scroll - each institution with its membership, role, and category.
The five EU institutions were where pooled sovereignty operated in practice. Two divisions matter for the exam. Supranational institutions act above the member states with their own institutional identity and pursue an EU-wide agenda. Intergovernmental institutions are composed of representatives of national governments and act through agreements between them. The distinction matters because supranational institutions are where pooled sovereignty most directly limited UK national control.
Three are supranational - they act above the states. Two are intergovernmental - they ARE the states meeting together. Scroll through each.
The Commission is the EU executive. Composed of one Commissioner per member state, each nominated by their government but expected to act in the EU interest, not their state's interest. Proposes EU laws (it is the only institution that can propose legislation), prepares the EU budget, enforces EU laws on member states and other governments, runs day-to-day EU administration. Because Commissioners are meant to act for the EU rather than for their state, the Commission is supranational - it sits above the national level.
The European Council is composed of the heads of government of the member states (Prime Ministers and Presidents). Meets up to four times a year. Takes the major strategic decisions: admission of new member states, treaty changes, the broad direction of EU policy. Because it is composed of national leaders representing their countries, the European Council is intergovernmental - it is the member states meeting together. Do not confuse with the Council of the European Union or with the Council of Europe (which is a separate non-EU body).
Also called the Council of Ministers. Composed of ministers from each member state, with the specific minister attending depending on the policy area being discussed (agriculture ministers for farm policy, foreign ministers for foreign policy, etc.). Takes decisions on whether to adopt legislation, working in co-operation with the European Parliament. Like the European Council, the Council of the EU is intergovernmental - composed of national government representatives. The post-Lisbon move to qualified majority voting on many issues means individual member states can be outvoted - which became part of the Brexit complaint about lost national control.
The only directly elected EU institution. MEPs elected by EU citizens every five years; the UK no longer has MEPs since Brexit. Has the right of co-decision on most legislation with the Council of the EU; has a say in the adoption of the EU budget; can accept or reject nominations to the Commission. The Parliament is supranational because MEPs sit in European political groupings (Socialists, EPP, Greens etc.) rather than purely as national delegations.
The ECJ enforces EU law and resolves disputes between member states. Sits in Luxembourg (not to be confused with the European Court of Human Rights in Strasbourg, which is part of the separate Council of Europe). The ECJ is where pooled sovereignty bites hardest - its rulings bind member state courts. The Factortame case (Part 4) is the most important UK example. Post-Brexit the ECJ no longer has direct jurisdiction in the UK - except in Northern Ireland under the Windsor Framework, and now (per Starmer's 2025 reset) over the UK-EU fish trade.
The Brexit complaint was strongest against the supranational bodies - the Commission proposing laws, the Parliament co-deciding them, the ECJ enforcing them. These were the institutions most clearly acting "above" the UK. The intergovernmental bodies (the two Councils) were where the UK government had a direct voice. The Lisbon Treaty's expansion of qualified majority voting meant the UK could be outvoted even in the intergovernmental bodies - which intensified the sovereignty complaint.
The single most important UK case on EU law and sovereignty.
The Factortame case (1990) is the textbook illustration of how EU membership constrained UK parliamentary sovereignty in practice. The UK government had passed the Merchant Shipping Act 1988 which required British-registered fishing vessels to be majority British-owned - a measure designed to stop Spanish fishing companies fishing under the UK quota through UK shell companies. A Spanish fishing company called Factortame argued the Act broke EU law because it discriminated against EU nationals exercising their freedom of movement and freedom of establishment.
The case went to the European Court of Justice. The ECJ ruled that EU law had priority over UK law in the areas of EU competence. The UK House of Lords (then the highest UK court) confirmed that EU law could overrule UK law. The Merchant Shipping Act 1988 was disapplied to the extent it conflicted with EU law.
This is the case that shows pooled sovereignty as a real constitutional fact, not an abstract concept. While the UK was a member of the EU, an Act of Parliament could be effectively struck down by the ECJ. This is something the courts of the UK have never been able to do under domestic constitutional law - parliamentary sovereignty means UK courts cannot strike down statutes. But EU law could.
Scroll through the timeline of how the UK left the EU.
From the 2016 referendum to the 31 January 2020 departure took three and a half years. Two key Supreme Court cases (Miller 1 and Miller 2) reinforced parliamentary sovereignty against executive overreach during the process. Scroll through the major steps.
David Cameron renegotiated UK membership terms in 2015-16 and put the result to a referendum. 23 June 2016: 52% Leave, 48% Remain. Turnout 72%. Cameron resigned the morning after. Theresa May took over in July 2016. The referendum was advisory in legal terms - Parliament was sovereign over whether to act on it - but politically binding because both major parties accepted the result.
The Government tried to trigger Article 50 (the legal mechanism for leaving the EU) using the prerogative power - without an Act of Parliament. Gina Miller challenged this. The UK Supreme Court ruled 8-3 that Article 50 could only be triggered by an Act of Parliament, not by executive action alone, because triggering it would change UK law (specifically, it would set in motion the process of removing rights derived from EU law) and only Parliament can change UK law. The European Union (Notification of Withdrawal) Act 2017 followed. Miller 1 reinforced parliamentary sovereignty against executive overreach.
Boris Johnson as PM prorogued (suspended) Parliament for five weeks in autumn 2019, immediately before the Brexit deadline. The Supreme Court ruled 11-0 that the prorogation was unlawful, void, and of no effect - because the government cannot use prerogative powers to prevent Parliament from performing its constitutional functions. Lady Hale delivered the judgment (with her famous spider brooch). Miller 2 is the strongest contemporary example of the judiciary checking executive overreach in the UK system.
Boris Johnson won the December 2019 election with a clear majority and an "oven-ready" Brexit deal. The European Union (Withdrawal Agreement) Act 2020 implemented the deal in UK law. The UK formally left the EU on 31 January 2020. A transition period ran to 31 December 2020 during which the UK continued to follow most EU rules. The EU-UK Trade and Cooperation Agreement was agreed in late December 2020 and took effect 1 January 2021.
The Retained EU Law (Revocation and Reform) Act 2023 ended the principle of EU law supremacy in the UK system. Most EU-derived law had been incorporated into UK law to ensure continuity at the moment of departure; this Act began the process of either retaining, amending or removing it. The Act formally ended the special status of EU-derived law - it now sits as ordinary UK law that Parliament can change.
Legally: parliamentary sovereignty is reasserted. UK law is no longer subordinate to EU law (with the exceptions covered in Part 6). The ECJ no longer has direct UK jurisdiction (with the same exceptions). Factortame-style cases cannot now happen for new disputes. The Miller cases during the process reinforced Parliament's sovereignty against executive attempts to bypass it. The legal sovereignty question is settled: Parliament has it back.
Scroll - the EU influence that did not go away.
Despite the departure, the UK still has a substantial relationship with the EU. The Northern Ireland question turned out to be very difficult to solve and produced ongoing EU jurisdiction in part of the UK. The Trade and Cooperation Agreement governs the day-to-day trading relationship. And under Keir Starmer's government from July 2024 the UK has moved toward closer alignment - including a 2025 reset that returns some areas to ECJ jurisdiction.
The Northern Ireland Protocol and Windsor Framework. The UK-EU Trade and Cooperation Agreement. Starmer's 2025 reset of the relationship. Scroll through each.
The Northern Ireland Protocol was negotiated as part of the original 2019 withdrawal deal. To avoid a hard border on the island of Ireland (which would have breached the Good Friday Agreement 1998), Northern Ireland continued to follow many EU single-market rules on goods, with checks at ports between Great Britain and Northern Ireland. The ECJ retained some jurisdiction in Northern Ireland on these areas. The arrangement caused major political difficulties (the DUP refused to participate in Stormont for two years). The Windsor Framework (February 2023) renegotiated the arrangement under Sunak, simplifying the GB-NI checks (a "green lane" for goods staying in NI). Northern Ireland still follows many EU rules; the ECJ retains limited jurisdiction - so for one part of the UK, pooled sovereignty has not fully ended.
The EU-UK Trade and Cooperation Agreement 2021 governs the post-Brexit trading relationship. It allows tariff-free and quota-free trade in goods (provided rules-of-origin requirements are met) but introduces customs checks, regulatory checks, and increased paperwork. Service trade is much more restricted than under Single Market membership. The TCA does not include the Single Market or the Customs Union; it is more like a deeper version of a normal trade agreement. The TCA established joint UK-EU committees to manage disputes but with the ECJ only marginally involved.
Keir Starmer's Labour government from July 2024 has moved toward closer EU alignment without rejoining the Single Market or Customs Union. The May 2025 UK-EU summit produced a reset of the Trade and Cooperation Agreement including new arrangements on defence cooperation, food and animal product trade (sanitary and phytosanitary), and a fishing agreement that runs to 2038. The fish part of the deal puts the ECJ back as the legal arbiter for UK-EU trade on fish - a small but constitutionally significant return of ECJ jurisdiction over UK matters. Some critics see this as a partial reversal of Brexit sovereignty gains; defenders argue it is the necessary cost of better access.
Most of the UK is outside the EU legal system. Northern Ireland is partly inside. Trade in goods works but is more difficult. Trade in services is much more difficult. The Starmer reset is moving toward closer alignment in specific areas - including putting the ECJ back as arbiter on fish. Sovereignty in legal terms is largely back with Parliament, but the UK has chosen to accept some EU jurisdiction in exchange for better trade access.
Scroll - four ways to read the post-Brexit sovereignty picture.
This is where Paper 2 sovereignty essays land. The legal answer is "yes, Parliament got it back". The political answer is more complicated. Four dimensions to weigh.
Yes Parliament got it back (the legal answer). No, the executive has gained at Parliament's expense (the political answer). Devolution further fragments sovereignty. And the UK still chooses to accept some EU jurisdiction. Scroll the four readings.
The most direct reading. EU law no longer has supremacy in the UK. The ECJ no longer has direct UK jurisdiction (with the Northern Ireland and fish-trade exceptions). The Retained EU Law Act 2023 ends the special status of EU-derived law. Factortame-style cases cannot happen. Parliament can in principle pass any law on any subject. The legal sovereignty question is settled in Parliament's favour.
The strongest counter-reading. The Brexit process and the post-Brexit regulatory rebuild required vast amounts of secondary legislation (statutory instruments) made by ministers rather than Acts passed by Parliament. The European Union (Withdrawal) Act 2018 gave ministers wide-ranging powers to make changes to retained EU law by statutory instrument. Scrutiny of these powers by Parliament is generally weaker than scrutiny of full Bills. Add the Trump-style executive-order parallel and a clear pattern emerges: Parliament reclaimed sovereignty from the EU and has been losing it to the executive. Power has moved inside the UK system, not just back from outside it.
Sovereignty in the UK is also distributed across the devolved parliaments. Scotland, Wales and Northern Ireland have substantial law-making powers in devolved areas (health, education, housing, justice for Scotland and NI). The Internal Market Act 2020 imposed a UK-wide approach to internal trade after Brexit and was seen by the Scottish and Welsh governments as overriding their devolved competences. Devolution complicates the simple "Parliament is sovereign" story. Sovereignty in practice is divided between Westminster, Edinburgh, Cardiff, Belfast - and (post-Sewel Convention) Westminster is supposed not to legislate on devolved matters without consent.
The Northern Ireland Protocol / Windsor Framework keeps ECJ jurisdiction over NI on goods. Starmer's 2025 reset returns ECJ jurisdiction over the UK-EU fish trade. The UK remains a signatory to the European Convention on Human Rights (ECHR) - which is separate from the EU but is sometimes confused with it. So the UK in 2025 has reclaimed full legal sovereignty in principle but is choosing in specific areas to accept external jurisdiction in exchange for better access or stability. Sovereignty is a choice, not a fact - and the UK keeps making choices that involve sharing it.
The strongest essay does NOT just answer "yes Parliament got sovereignty back". It holds the four readings together: legal sovereignty restored; political sovereignty has moved to the executive in important ways; devolution fragments where sovereignty actually sits; and the UK continues to choose some shared sovereignty arrangements. Sovereignty has moved in the UK since 2016 - but not in a single direction. A 24-mark or 30-mark answer that captures this complexity sits in the top band.
The single most important non-confusion in this topic.
The ECHR was drafted in 1950 by the Council of Europe - a separate body founded in 1949, originally as a post-WWII rights protection mechanism. The Council of Europe has 46 member states including Russia until 2022 (expelled after Ukraine invasion). Many of its members are not EU members. The Council of Europe is not the EU.
The ECHR is enforced by the European Court of Human Rights (ECtHR) sitting in Strasbourg, France. Do not confuse with the European Court of Justice (ECJ) which sits in Luxembourg and is the EU court.
The Human Rights Act 1998 made the ECHR enforceable in UK courts. UK laws must be compatible with ECHR rights (HRA section 3 requires courts to interpret legislation compatibly where possible); UK courts can issue declarations of incompatibility (HRA section 4) when this is not possible. UK judges must interpret law in light of the ECHR. The UK remains a signatory to the ECHR - the HRA is the domestic vehicle for that signature.
Cases like Hirst v UK (2005) on prisoner voting, and R (Begum) on citizenship deprivation, are ECHR cases, NOT EU cases. They involve the Strasbourg court, not Luxembourg. Confusing the two is one of the most common Paper 2 errors.
The likely 24-mark and 30-mark questions and the structure that answers them.
The architecture. Paper 2 sovereignty questions usually pit one branch against another, or one era against another. The strongest answers carry Factortame as the pre-Brexit case, Miller 1 and 2 as the Brexit-process cases, Retained EU Law Act 2023 and Windsor Framework 2023 as the post-Brexit cases, and the Starmer 2025 reset as the contemporary kicker.
Approach: Three themes. Theme 1: legal sovereignty has been reclaimed from the EU (Retained EU Law Act 2023; Factortame impossible now). Theme 2: but political sovereignty has shifted from Parliament to the executive via secondary legislation (EU Withdrawal Act 2018 wide powers; statutory instruments boom). Theme 3: devolution and the Internal Market Act 2020 fragment sovereignty further; the UK still chooses some EU jurisdiction (NI Protocol; Starmer 2025 fish deal). Judgement: sovereignty has moved in MULTIPLE directions - not just back to Parliament.
Approach: Three themes. Theme 1: legally yes (Retained EU Law Act 2023; Miller 1 reinforced Parliament's central role; ECJ no longer has UK jurisdiction in most areas). Theme 2: politically no - executive has gained through secondary legislation. Theme 3: shared sovereignty arrangements continue (Northern Ireland Protocol / Windsor Framework; Starmer's 2025 fish deal puts ECJ back on this area). Judgement: legal sovereignty yes, full political sovereignty no - and the UK keeps choosing partial sharing.
Approach: Three themes. Theme 1: the EU genuinely constrained UK sovereignty - Factortame; EU law supremacy; Four Freedoms limiting domestic control. Theme 2: but UK retained substantial control - intergovernmental institutions (European Council, Council of EU) gave national governments real voice; EU competence was bounded; opt-outs (Euro, Schengen). Theme 3: post-Brexit reality has shown both the gains (Retained EU Law Act 2023) and the costs (TCA trade frictions; rejoining ECHR alignment). Judgement: the impact was real but the Brexit framing of total subordination was rhetorical.
Approach: Three themes. Theme 1: executive gains from Brexit secondary-legislation explosion (EU Withdrawal Act 2018 wide powers). Theme 2: but Miller 1 and 2 reinforced Parliament's central role against executive overreach; the courts checked Boris Johnson. Theme 3: devolution and Lords still check the executive in important ways; majority size matters more than any structural shift. Judgement: executive gains are real but constrained - the structure is not yet broken.
Parliamentary sovereignty (Dicey). The constitutional rule that Parliament can make or unmake any law; no Parliament can bind a future Parliament; no body above Parliament can overrule it.
Legal sovereignty. The theoretical power - what the constitution says can be done. Parliament has legal sovereignty.
Political sovereignty. The reality of power - what actually gets decided and by whom. Executive, courts, public, and (1973-2020) EU institutions all share.
Pooled sovereignty. The arrangement under which member states share decision-making with EU institutions in EU competence areas.
Four Freedoms. The free movement of goods, people, services, and capital across EU member states; the foundation of the Single Market.
Supranational. An EU institution that acts above the member states with its own institutional identity (European Commission, Parliament, ECJ).
Intergovernmental. An EU institution composed of representatives of national governments (European Council, Council of the European Union).
European Communities Act 1972. The UK statute that brought EU law into UK law on accession.
Maastricht Treaty 1992. Created the European Union from the European Economic Community; expanded EU competence beyond trade.
Lisbon Treaty 2007/9. Deepened EU integration; expanded qualified majority voting; strengthened the European Parliament.
Factortame case (1990). The textbook UK case showing EU law supremacy over UK Acts of Parliament. Merchant Shipping Act 1988 ruled invalid to the extent it conflicted with EU law.
R (Miller) v Secretary of State for Exiting the EU (Miller 1, January 2017). Supreme Court ruled 8-3 that Article 50 could only be triggered by an Act of Parliament, not by prerogative.
R (Miller) v The Prime Minister (Miller 2, September 2019). Supreme Court ruled 11-0 that Boris Johnson's prorogation of Parliament for five weeks was unlawful, void, and of no effect.
EU (Withdrawal Agreement) Act 2020. The UK statute that implemented the Brexit withdrawal deal; UK formally left 31 January 2020.
EU-UK Trade and Cooperation Agreement (TCA) 2021. The post-Brexit trade deal. Tariff-free goods trade with checks; services much restricted; no Single Market or Customs Union access.
Retained EU Law (Revocation and Reform) Act 2023. Ended the principle of EU law supremacy in the UK; EU-derived law now treated as ordinary UK law.
Northern Ireland Protocol. Part of the original 2019 withdrawal deal; kept Northern Ireland following many EU single-market rules to avoid a hard Irish border.
Windsor Framework (February 2023). Sunak-era renegotiation simplifying the GB-NI checks under the Protocol while keeping the ECJ's limited NI jurisdiction.
Internal Market Act 2020. UK statute imposing a UK-wide approach to internal trade post-Brexit; objected to by Scottish and Welsh governments as overriding devolution.
Sewel Convention. The political convention that Westminster will not normally legislate on devolved matters without the consent of the devolved legislatures; not legally binding.
European Convention on Human Rights (ECHR). Drafted 1950 by the Council of Europe; NOT the EU. Separate court (ECtHR) in Strasbourg; separate membership.
Human Rights Act 1998. Incorporated ECHR rights into UK law. Section 3 requires courts to interpret legislation compatibly with the ECHR where possible. Section 4 allows declarations of incompatibility.
Council of Europe. Separate international body founded 1949 with 46 member states; sponsors the ECHR. NOT the EU.