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R (Miller) v Secretary of State for Exiting the European Union [2017] 

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This case was seen by the Supreme Court of the United Kingdom. It concerned whether the Secretary of State could trigger article 50 of the Treaty of Lisbon without prior Parliamentary legislation, as well as whether the devolution settlements imposed legal restrictions on the Secretary of State’s exercise of this power.

I. Facts of the Case 

From about 1960, the UK government was negotiating with the European Economic Community (EEC, which later became the EU) about joining them and associated European organisations. On 22 January 1972, after two Houses of Parliament approved the government’s decision to join the EEC, ministers signed a Treaty of Accession. After the passing of the European Communities Act 1972, the ministers ratified the Accession Treaty and the UK became an EEC member on 1 January 1973, which meant that the EEC law took effect as domestic law of the UK. 

The Treaty of Lisbon introduced into the EU treaties the first time an express provision entitling member states to withdraw from the EU by introducing article 50 into the treaty. In 2015, the UK government enacted the European Union Referendum Act 2015, and the ensuing referendum resulted in a majority favouring the withdrawal from the EU. On 7 December 2016, the House of Commons resolved to respect the referendum and called on the government to invoke article 50 by 31 March 2017. 

Afterwards, Gina Miller and Deir dos Santos initiated the proceedings against the Secretary of State for Exiting the European Union on the ground that he cannot send the notice of withdrawal without prior Parliamentary legislation, which came all the way to the Supreme Court. Meanwhile, Steven Agnew, Raymond McCord and others sued the Secretary of State for Exiting the European Union and the Secretary of State for Northern Ireland on the same issue, and five devolution issues were referred to the Supreme Court. 

II. Issues of the Case 

The issue before the Supreme Court regarding Gina Miller and Deir dos Santos’ claim was whether a formal notice of withdrawal from the EU can lawfully be given by ministers without prior primary legislation. 

The five devolution questions were as follows: 

  1. Does any provision of the Northern Ireland Act 1998, read together with the Belfast Agreement and the British-Irish Agreement, have the effect that primary legislation is required before Notice can be given? 
  2. If the answer is “yes”, is the consent of the Northern Ireland Assembly required before the relevant legislation is enacted? 
  3. If the answer to question (i) is “no”, does any provision of the NI Act read together with the Belfast Agreement and the British-Irish Agreement operate as a restriction on the exercise of the prerogative power to give Notice? 
  4. Does section 75 of the NI Act prevent exercise of the power to give Notice in the absence of compliance by the Northern Ireland O–ce with its obligations under that section? 
  5. Does the giving of Notice without the consent of the people of Northern Ireland impede the operation of section 1 of the NI Act? 

III. The Court’s Decision and the Rationes Decidendi of the Case 

The Supreme Court, by a majority, ruled in favour of Gina Miller and Deir dos Santos on the question whether the Secretary of State should seek permission from a statute before serving the notice of withdrawal from the EU. However, it dismissed the claimants in relation to the Northern Ireland questions, ruling that the devolution settlements did not impose legal restrictions on the power of withdrawal. 

Gina Miller’s claim was approved for the following reasons: 

  1. Although the European Communities Act 1972 authorised a dynamic process whereby EU law became a source of UK law, it can be repealed by any other statute. 
  2. However, the 1972 Act ss 2(1) and (2) did not authorise the use of prerogative power to cut off the source of EU law entirely. 
  3. This is because withdrawing from the EU involves such a significant constitutional change and impacts such a wide range of domestic rights that it cannot be carried out by the Royal prerogative without primary legislation. 
  4. This would be the case unless Parliament expressly legislate to authorise the use of such a power. 
  5. The construction of the 1972 Act points towards the need to obtain legislative approval before using such a power. 
  6. If prerogative power could be used in such a way without legislative approval, the ministers would have been able to withdraw from the EU without legislation at any time after 2 January 1973 when the UK became a member of the EU. 
  7. In regards the referendum, ministerial statements about its effect are not law. 
  8. Further, referendum does not have legal effect without further statutory provision, despite its significant political effects. 
  9. Similarly, the resolution by the House of Commons was not legislation and therefore could not authorise the Secretary of State’s power of withdrawal alone. 

Regarding the devolution questions, the Supreme Court decided as follows: 

  1. Parliament passed the devolution Acts on the assumption that the United Kingdom would be a member of the EU. However, the Acts did not go further and require the UK to remain part of the EU, and the power to decide whether to stay in the EU remained with Parliament. 
  2. The Northern Ireland Act 1998 s 75 did not impose on the Secretary of State for Northern Ireland a positive obligation in relation to withdrawal from the EU. 
  3. The NI Act s 1 regulates only the issue of whether Northern Ireland will stay a part of the UK. It did not regulate the issue of exiting the European Union and did not require the consent of a majority of Northern Irish people before such a decision. 
  4. The Sewel Convention did not have legal power and therefore could not affect Parliament’s decision to withdraw from the EU.  

IV. The Significance of the Case

The case reiterated the significance of Parliamentary sovereignty by making clear that the use of prerogative power cannot change statutory law, and that Parliamentary legislation takes precedence over devolved legislatures. Furthermore, it restrained arbitrary exercise of executive power by confirming the principle that the Crown cannot alter the law of the land, including common law and statutory law. However, its political significance in relation to exiting the European Union appears limited as subsequent primary legislation did not prevent the Crown issuing a notice of withdrawal from the EU. 

Appellate History

  • The Supreme Court of the United Kingdom [2017] –Gina Miller’s claim approved,Devolution arguments superseded or rejected
  • Divisional Court [2016] – Gina Miller’s claim approved 
  • Northern Ireland High Court [2016] – Devolution arguments rejected


  • Parliamentary Sovereignty
  • Devolution 

Submission Details

Reviewed By Ross Birkbeck
Submitted By Iona Lindsay
First Published 26th July 2022

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UK legislation:

  • Bill of Rights 1688/9
  • Claim of Right Act 1689
  • Communications Act 2003
  • Act of Settlement 1701
  • Union with Scotland Act 1706
  • Union with England Act 1707
  • Acts of Union 1800
  • Carriage of Goods by Sea Act 1971
  • Immigration Act 1971
  • European Communities Act 1972
  • Referendum Act 1975
  • European Assembly Elections Act 1978
  • Scotland Act 1978
  • European Communities (Amendment) Act 1986
  • Immigration Act 1988
  • Income and Corporation Taxes Act 1988
  • European Communities (Amendment) Act 1993
  • European Communities (Amendment) Act 1998
  • Northern Ireland Act 1998
  • Scotland Act 1998
  • Political Parties, Elections and Referendums Act 2000
  • European Communities (Amendment) Act 2002
  • European Parliamentary Elections Act 2002
  • Government of Wales Act 2006
  • European Communities (Amendment) Act 2008
  • Constitutional Reform and Governance Act 2010
  • Taxation (International and Other Provisions) Act 2010
  • European Union Act 2011
  • Parliamentary Voting System and Constituencies Act 2011
  • Scotland Act 2012
  • Wales Act 2014
  • European Union Referendum Act 2015
  • Scotland Act 2016

UK and Privy Council caselaw:

  • Case of Proclamations (1611) 12 Co Rep 74,
  • Secretary of State in Council of India v Kamachee Boye Sahaba (1859) 13 Moo PCC 22
  • Rustomjee v The Queen (1876) 2 QBD 69, The Zamora [1916] 2 AC 77
  • Attorney General v De Keyser’s Royal Hotel Ltd [1920] AC 508
  • Joyce v Director of Public Prosecutions [1946] AC 347
  • Burmah Oil Co (Burma Trading) Ltd v Lord Advocate [1965] AC 75
  • Post Office v Estuary Radio Ltd [1968] 2 QB 740, Madzimbamuto v Lardner-Burke [1969] 1 AC 645, Blackburn v Attorney General [1971] 1 WLR 1037
  • McWhirter v Attorney General [1972] CMLR 882
  • Bulmer Ltd v Bollinger [1974] Ch 401
  • Attorney General v Jonathan Cape Ltd [1976] 1 QB 752
  • Laker Airways Ltd v Department of Trade [1977] QB 643
  • Macarthys Ltd v Smith [1981] ICR 785
  • Council of Civil Service Unions v Minister for the Civil Service [1985] AC 374
  • JH Rayner (Mincing Lane) Ltd v Department of Trade and Industry [1990] 2 AC 418
  • R v Secretary of State for Transport, Ex p Factortame Ltd (No 2) [1991] 1 AC 603 and (No 5) [2000] 1 AC 524
  • R v Secretary of State for Foreign and Commonwealth Affairs, Ex p Rees-Mogg [1994] QB 552
  • R v Secretary of State for the Home Department, Ex p Fire Brigades Union [1995] 2 AC 513
  • Higgs v Minister of National Security [2000] 2 AC 228
  • R v Secretary of State for the Home Department, Ex p Simms [2000] 2 AC 115
  • R (Morgan Grenfell & Co Ltd) v Special Commissioner of Income Tax [2002] UKHL 21; [2003]1 AC 563,
  • R (Morgan Grenfell & Co Ltd) v Special Commissioner of Income Tax [2003] 1 AC 563
  • Thoburn v Sunderland City Council [2003] QB 151
  • R (Bancoult) v Secretary of State for Foreign and Commonwealth Affairs (No 2) [2009] AC 453
  • Imperial Tobacco v Lord Advocate 2012 SC 297
  • R (Buckinghamshire County Council) v Secretary of State for Transport [2014] 1 WLR 324
  • Pham v Secretary of State for the Home Department [2015] 1 WLR 1591
  • Lee v McArthur [2016] NICA 55, CA(NI)
  • Re JR65’s Application [2016] NICA 20
  • Re McCord, Judicial Review [2016] NIQB 85
  • R (Miller) v The Secretary of State for Exiting the European Union [2016] EWHC 2768 (Admin)
  • R (Shindler) v Chancellor of the Duchy of Lancaster [2016] 3 WLR 1196
  • R (The Public Law Project) v Lord Chancellor [2016] AC 1531

International treaties and agreements:

  • Hague Rules
  • Treaty Establishing the European Atomic Energy Community
  • Treaty of Rome
  • European Free Trade Agreement
  • Treaty of Accession
  • Single European Act
  • Maastricht Treaty on European Union
  • Kyoto Protocol on Climate Change
  • Amsterdam Treaty
  • Belfast Agreement
  • Treaty of Nice
  • Treaty of Lisbon
  • Treaty on the Functioning of the European Union

EU regulation and directives:

  • Council Regulation (EC) No 2201/2003
  • Working Time Directive 2003/88/EC
  • Citizens’ Directive 2004/38/EC

EU caselaw:

  • Van Gend en Loos (Case C-26/62) [1963] ECR 1
  • Costa v ENEL (Case C-6/64) [1964] ECR 585
  • Marleasing v La Comercial Internacional de Alimentacion SA (Case C-106/89) [1990] ECR I-4135
  • Brasserie du Pêcheur SA v Germany; R v Secretary of State for Transport (Ex p Factortame Ltd) (No 4) (Joined Cases C-46/93 and C-48/93) [1996] QB 404
  • Köbler v Austria (Case C-224/01) [2004] QB 848)

Canadian caselaw:

  • Re Resolution to Amend the Constitution [1981] 1 SCR 753
  • Friends of the Earth v Canada (Governor in Council), 2008 FC 118
  • Turp v Ministry of Justice & Attorney General of Canada 2012 FC 893
Updated on July 12, 2023

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