has leaving eu increased parliamentary sovereignty?

Structure of essay?

• P1 - UK is no longer bound by EU structures

• P2 - Parliament can now legislative on previously EU controlled topics

• P3 - Brexit Process

P1 - UK is no longer bound by EU structures - increased sovereignty

• Increased sovereignty aa there is no longer a higher court that can strike down legislation it passes, meaning that parliament is not subject to EU law or jurisdiction from the European Court of Justice.

• When Britain was a member of the EU, the UK accepted supremacy of EU law over domestic laws.

  • This meant that if a law was passed by UK Parliament that contradicted EU law, the ECJ could strike it down and force parliament to change it.

  • Now that Britain has left the EU, there is no higher court which can strike down legislation, thus restoring sovereignty,.

• The supremacy of EU law was confirmed in the 1990 Factortame Case

  • This is when the Law Lords ruled that the Merchant Shipping Act 1988, which was passed by UK Parliament, breached EU law as it required UK registered ships to have a majority of British Owners.

  • Parliament was forced to unmake the law and set aside primary legislation which was found to be incompatible with EU law provisions, showing how under EU membership parliament was not truly sovereign as it could be overridden by a higher legal authority.

P1 - UK is no longer bound by EU structures - has not increased sovereignty

• However, it can be argued that leaving the EU has not increased sovereignty as it continues to be limited in Northern Ireland.

• EU law still applies in Northern Ireland, meaning Parliament is still constrained in important policy areas.

  • Even following the Windsor Framework (which amended the Northern Ireland Protocol), Northern Ireland continues to follow parts of EU single market law, and the application of EU law in N.I. is subject to EU oversight.

  • Crucially, where EU law still applies in N.I., the UK could be taken to the ECJ if it didn’t comply, which limits parliaments ability to legislation across the whole country.

• As of 2026, over 300 EU regulations, directive and decisions, continue to apply in N.I.

  • The government has committed to not debate from these, and when the EU amends or replaces these acts, those changes automatically apply in N.I.

  • The fact the EU can arbitrate against the UK even though it is not a strict member demonstrates how EU law is higher than parliamentary sovereignty in some parts of the UK.

P2 - Parliament can now legislate on law previously decided by EU - increased sovereignty

• Increased sovereignty as the UK Parliament can now legislate on all areas of policy, which was not the case when the UK was in the EU.

• When the UK was a member of the EU, many important policy areas were either shared competences or exclusive EU competences, meaning the EU institutions could pass binding legislation that the UK had to follow.

  • This includes key areas such as trade, agriculture, aspects of justice, fisheries, environmental regulation, thus limiting sovereignty as it could not legislate on these areas.

• Between 1993 and 2014, there were 231 Acts of Parliament passed that implemented EU obligations.

  • A good example of Parliament legislating in an area of policy that the EU used to have significant control over is the Border Security, Asylum and Immigration Act, which received Royal Assent on the 2nd of December 2025.

  • Under EU membership, immigration enforcement was governed by common rules set out in the Return Directive, which member states were required to implement.

    • This shows that memership of the EU dilutes and effectively removes autonomy of Parliamentary sovereignty.

P2 - Parliament can now legislate on law previously decided by EU - hasn’t increased sovereignty

• Has not increased parliamentary sovereignty because the UK Parliament was already sovereign in most major domestic policy areas while the UK was an EU member.

• Whilst in the EU, the UK had opt-outs from some EU policies it opposed, therefore limiting the amount of sovereignty that lost by UK Parliament.

  • For example, the UK retained sovereignty over most areas of taxation, welfare, education, policing, defence, and constitutional matters when a member of the EU.

• In addition, the UK’s membership of the EU increased its pooled sovereignty, as the UK voluntarily shared decision-making in return for influence over EU-wide rules and greater global influence as a result

  • This means that sovereignty was not ‘lost’, and Parliament still remained key law-making body in many areas.

• The UK Parliament had a series of important EU opt-outs. Britain opted out from adopting the Euro under the Maastricht Treaty as a currency as they were not willing to surrender economic sovereignty and control of interests rates to the European Central Bank.

  • This shows that even inside the EU, the UK still had legal sovereignty in most areas and important powers were already retained.

P3 - Brexit Process - hasn’t increased sovereignty

• Leaving the EU has not increased sovereignty as the Brexit process created a new form of ‘popular sovereignty’, which politically constrained Parliament.

• Although the 2016 EU referendum was not politically binding, it became binding in practice. As a result, Parliament’s sovereignty was not limited by EU institutions, but by the electorate directly.

  • Traditionally, the UK constitution is based on representative democracy, where sovereignty is exercised through Parliament and the public choose decision-makers through elections.

  • However, BREXIT represented a shift towards direct democracy, where the electorate made major constitutional decisions themselves.

    • This undermines sovereignty because in practice, Parliament was compelled to deliver a policy outcome even when many MPs disagreed with it.

    • Brexit may have restored legal sovereignty from the EU, but it also reduced Parliaments political sovereignty by constraining Parliaments ability to act freely.

• In 2016, the EU referendum produced a leave vote despite around 74% of MPs supporting Remain, and the official position of the largest party in Parliament was remain.

  • Despite this, Parliament voted to trigger Article 50 nd later supported the Withdrawal Agreement, which formally took the UK out of the EU, which happened because 52% of voters supported leave, and Parliament was pressured into implementation.

P3 - Brexit process - increased sovereignty

• However it can be argued that the Brexit process can be seen as strengthening parliamentary sovereignty as a number of Supreme Court cases protected parliamentary sovereignty against an overarching executive

  • The process of Brexit reaffirmed parliaments sovereignty in relation to the executive and ensured that the sovereignty regained from the EU goes to Parliament and not the government.

• In Miller v The Prime Minister (2019), the S.C. ruled that Boris Johnson’s decision to prorogue Parliament for give weeks was unlawful because it prevented Parliament from carrying out its constitutional functions.

  • The ruling meant Parliament’s not legally prorogued, allowing it to immediately resume business as it was nullified.

  • It held that the PMs prerogative power to prorogue parliament cannot be used to frustrate Parliamentary scrutiny, strengthening its ability to hold government to account .

• This shows that by leaving the EU, or rather the process of doing so, strengthened Parliamentary sovereignty as the courts acted to protect parliaments ability to hold the government to account by reinforcing legal sovereignty and primacy over the executive.