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Table of Contents

  1. Acknowledgments
  2. Chapter one: Defining the constitution
  3. Chapter two: Parliamentary sovereignty
  4. Chapter three: The rule of law and the separation of powers
  5. Chapter four: The royal prerogative
  6. Chapter five: The House of Commons
  7. Chapter six: The House of Lords
  8. Chapter seven: The electoral system
  9. Chapter eight: Parliamentary privilege
  10. Chapter nine: Constitutional conventions
  11. Chapter ten: Local government
  12. Chapter eleven: Parliamentary sovereignty within the European Union
  13. Chapter twelve: The governance of Scotland and Wales
  14. Chapter thirteen: Substantive grounds of judicial review 1: illegality, irrationality and proportionality
  15. Chapter fourteen: Procedural grounds of judicial review
  16. Chapter fifteen: Challenging governmental decisions: the process
  17. Chapter sixteen: Locus standi
  18. Chapter seventeen: Human rights I: Traditional perspectives
  19. Chapter eighteen: Human rights II: Emergent principles
  20. Chapter nineteen: Human rights III: New substantive grounds of review
  21. Chapter twenty: Human rights IV: The Human Rights Act 1998
  22. Chapter twenty-one: Human rights V: The impact of The Human Rights Act 1998
  23. Chapter twenty-two: Human rights VI: Governmental powers of arrest and detention
  24. Chapter twenty-three: Leaving the European Union
    1. Treaty of Lisbon Art 50
    2. The European Union Referendum Act 2015
    3. R (Miller and another) v Secretary of State for Exiting the European Union [2016] EWHC 2768 (Admin) [2017] 2 WLR 583
    4. R (Miller and another) v Secretary of State for Exiting the European Union [2017] UKSC 5; [2017] 2 WLR 583
    5. The European Union (Withdrawal) Bill 2017

R (Miller and another) v Secretary of State for Exiting the European Union [2017] UKSC 5; [2017] 2 WLR 583


37.... Mr Eadie QC in his submissions on behalf of the Secretary of State..... argued that the fact that significant legal changes will follow from withdrawing from the EU Treaties does not prevent the giving of Notice, because the prerogative power to withdraw from treaties was not excluded by the terms of the 1972 Act, and that, in any event, "acts of the Government in the exercise of the prerogative can alter domestic law". More particularly, he contended that the 1972 Act gave effect to EU law only in so far as the EU Treaties required it, and that that effect was therefore contingent upon the United Kingdom remaining a party to those treaties. Accordingly, he said, in the 1972 Act Parliament had effectively stipulated that, or had sanctioned the result whereby, EU law should cease to have domestic effect in the event that minsters decided to withdraw from the EU Treaties.

38 Mr Eadie also relied on the fact that, while statutes enacted since 1972 have imposed Parliamentary controls over the exercise of prerogative powers in relation to the EU Treaties, they have not touched the prerogative power to withdraw from them. Implicitly, therefore, he contended, Parliament has recognised that the power to withdraw from such treaties exists and is exercisable without prior legislation. Mr Eadie also suggested that the 2015 Act was enacted on the assumption that the result of the referendum would be decisive. Mr Eadie's reliance on the legislation since 1972 was largely for the purpose of supporting his argument on the effect of the 1972 Act, but he did raise an argument that the legislation from 1972 to 2015 should be looked at as a whole. Also, in answer to a question from the court, he adopted a suggestion that, even if Parliamentary authority would otherwise have been required, the 2015 Act and the subsequent referendum dispensed with that requirement, but he did not develop that argument, in our view realistically......

The Royal prerogative and Treaties

47 The Royal prerogative encompasses the residue of powers which remain vested in the Crown, and they are exercisable by ministers, provided that the exercise is consistent with Parliamentary legislation. In Burmah Oil Co (Burma Trading) Ltd v Lord Advocate [1965] AC 75 , 101, Lord Reid explained that the Royal prerogative is a source of power which is "only available for a case not covered by statute". Professor HWR Wade summarised the position in his introduction to the first edition of what is now Wade & Forsyth, Administrative Law (1961), p 13:

"the residual prerogative is now confined to such matters as summoning and dissolving Parliament, declaring war and peace, regulating the armed forces in some respects, governing certain colonial territories, making treaties (though as such they cannot affect the rights of subjects), and conferring honours. The one drastic internal power of an administrative kind is the power to intern enemy aliens in time of war."

48 Thus, consistently with Parliamentary sovereignty, a prerogative power however well-established may be curtailed or abrogated by statute. Indeed, as Professor Wade explained, most of the powers which made up the Royal prerogative have been curtailed or abrogated in this way. The statutory curtailment or abrogation may be by express words or, as has been more common, by necessary implication. It is inherent in its residual nature that a prerogative power will be displaced in a field which becomes occupied by a corresponding power conferred or regulated by statute. This is what happened in the two leading 20th century cases on the topic, Attorney General v De Keyser's Royal Hotel Ltd [1920] AC 508 and Fire Brigades Union cited above. As Lord Parmoor explained in De Keyser , at p 575, when discussing the prerogative power to take a subject's property in time of war:

"The constitutional principle is that when the power of the Executive to interfere with the property or liberty of subjects has been placed under Parliamentary control, and directly regulated by statute, the Executive no longer derives its authority from the Royal Prerogative of the Crown but from Parliament, and that in exercising such authority the Executive is bound to observe the restrictions which Parliament has imposed in favour of the subject."

49 In Burmah Oil cited above, at p 101, Lord Reid described prerogative powers as a "relic of a past age", but that description should not be understood as implying that the Royal prerogative is either anomalous or anachronistic. There are important areas of governmental activity which, today as in the past, are essential to the effective operation of the state and which are not covered, or at least not completely covered, by statute. Some of them, such as the conduct of diplomacy and war, are by their very nature at least normally best reserved to ministers just as much in modern times as in the past, as indeed Lord Reid himself recognised in Burmah Oil , at p 100.

50 Consistently with paras 44-46, and the passage quoted from Professor Wade in para 47 above, it is a fundamental principle of the UK constitution that, unless primary legislation permits it, the Royal prerogative does not enable ministers to change statute law or common law. As Lord Hoffmann observed in R (Bancoult) v Secretary of State for Foreign and Commonwealth Affairs (No 2) [2009] AC 453 , para 44, "since the 17th century the prerogative has not empowered the Crown to change English common or statute law". This is, of course, just as true in relation to Scottish, Welsh or Northern Irish law. Exercise of ministers' prerogative powers must therefore be consistent both with the common law as laid down by the courts and with statutes as enacted by Parliament.

51 Further, ministers cannot frustrate the purpose of a statute or a statutory provision, for example by emptying it of content or preventing its effectual operation. Thus, ministers could not exercise prerogative powers at the international level to revoke the designation of Laker Airways under an aviation Treaty as that would have rendered a licence granted under a statute useless: Laker Airways Ltd v Department of Trade [1977] QB 643 -see especially at pp 718-719 and 728 per Roskill and Lawton LJJ respectively. And in Fire Brigades Union cited above, at pp 551-552, Lord Browne-Wilkinson concluded that ministers could not exercise the prerogative power to set up a scheme of compensation for criminal injuries in such a way as to make a statutory scheme redundant, even though the statute in question was not yet in force. And, as already mentioned in para 35 above, he also stated that it was inappropriate for ministers to base their actions (or to invite the court to make any decision) on the basis of an anticipated repeal of a statutory provision as that would involve ministers (or the court) pre-empting Parliament's decision whether to enact that repeal. ...

54 The most significant area in which ministers exercise the Royal prerogative is the conduct of the United Kingdom's foreign affairs. This includes diplomatic relations, the deployment of armed forces abroad, and, particularly in point for present purposes, the making of treaties. There is little case law on the power to terminate or withdraw from treaties, but, as a matter of both logic and practical necessity, it must be part of the Treaty-making prerogative. As Lord Templeman put it in JH Rayner (Mincing Lane) Ltd v Department of Trade and Industry [1990] 2 AC 418 , 476, "The Government may negotiate, conclude, construe, observe, breach, repudiate or terminate a treaty".

55 Subject to any restrictions imposed by primary legislation, the general rule is that the power to make or unmake treaties is exercisable without legislative authority and that the exercise of that power is not reviewable by the courts-see Civil Service Unions case cited above, at pp 397-398......

The status and character of the 1972 Act

60 Many statutes give effect to treaties by prescribing the content of domestic law in the areas covered by them. The 1972 Act does this, but it does considerably more as well. It authorises a dynamic process by which, without further primary legislation (and, in some cases, even without any domestic legislation), EU law not only becomes a source of UK law, but actually takes precedence over all domestic sources of UK law, including statutes. This may sound rather dry or technical to many people, but in constitutional terms the effect of the 1972 Act was unprecedented. Indeed, it is fair to say that the legal consequences of the United Kingdom's accession to the EEC were not fully appreciated by many lawyers until the Factortame litigation in the 1990s-see the House of Lords decisions in R v Secretary of State for Transport, Ex p Factortame Ltd (No 2) [1991] 1 AC 603 and (No 5) [2000] 1 AC 524 . Of course, consistently with the principle of Parliamentary sovereignty, this unprecedented state of affairs will only last so long as Parliament wishes: the 1972 Act can be repealed like any other statute. For that reason, we would not accept that the so-called fundamental rule of recognition (ie the fundamental rule by reference to which all other rules are validated) underlying UK laws has been varied by the 1972 Act or would be varied by its repeal.

61 In one sense, of course, it can be said that the 1972 Act is the source of EU law, in that, without that Act, EU law would have no domestic status. But in a more fundamental sense and, we consider, a more realistic sense, where EU law applies in the United Kingdom, it is the EU institutions which are the relevant source of that law. The legislative institutions of the EU can create or abrogate rules of law which will then apply domestically, without the specific sanction of any UK institution. It is true that the UK government and UK-elected members of the European Parliament participate in the EU legislative processes and can influence their outcome, but that does not diminish the point. Further, in the many areas of EU competence which are subject to majority decision, the approval of the United Kingdom is not required for its legislation to take effect domestically. It is also true that EU law enjoys its automatic and overriding effect only by virtue of the 1972 Act, and thus only while it remains in force. That point simply reflects the fact that Parliament was and remains sovereign: so, no new source of law could come into existence without Parliamentary sanction-and without being susceptible to being abrogated by Parliament. However, that in no way undermines our view that it is unrealistic to deny that, so long as that Act remains in force, the EU Treaties, EU legislation and the interpretations placed on these instruments by the Court of Justice are direct sources of UK law.

62 The 1972 Act did two things which are relevant to these appeals. First, it provided that rights, duties and rules derived from EU law should apply in the United Kingdom as part of its domestic law. Secondly, it provided for a new constitutional process for making law in the United Kingdom. These things are closely related, but they are legally and conceptually distinct. The content of the rights, duties and rules introduced into our domestic law as a result of the 1972 Act is exclusively a question of EU law. However, the constitutional processes by which the law of the United Kingdom is made is exclusively a question of domestic law......

65 In our view, then, although the 1972 Act gives effect to EU law, it is not itself the originating source of that law. It is, as was said on behalf of the Secretary of State echoing the illuminating analysis of Professor Finnis, the "conduit pipe" by which EU law is introduced into UK domestic law. So long as the 1972 Act remains in force, its effect is to constitute EU law an independent and overriding source of domestic law.....

Does the 1972 Act preclude the use of prerogative power to withdraw?


80 One of the most fundamental functions of the constitution of any state is to identify the sources of its law. And, as explained in paras 61 to 66 above, the 1972 Act effectively constitutes EU law as an entirely new, independent and overriding source of domestic law, and the Court of Justice as a source of binding judicial decisions about its meaning. This proposition is indeed inherent in the Secretary of State's metaphor of the 1972 Act as a conduit pipe by which EU law is brought into the domestic UK law. Upon the United Kingdom's withdrawal from the European Union, EU law will cease to be a source of domestic law for the future (even if the Great Repeal Bill provides that some legal rules derived from it should remain in force or continue to apply to accrued rights and liabilities), decisions of the Court of Justice will (again depending on the precise terms of the Great Repeal Bill) be of no more than persuasive authority, and there will be no further references to that court from UK courts. Even those legal rules derived from EU law and transposed into UK law by domestic legislation will have a different status. They will no longer be paramount, but will be open to domestic repeal or amendment in ways that may be inconsistent with EU law.

81 Accordingly, the main difficulty with the Secretary of State's argument is that it does not answer the objection based on the constitutional implications of withdrawal from the EU. As we have said, withdrawal is fundamentally different from variations in the content of EU law arising from further EU Treaties or legislation. A complete withdrawal represents a change which is different not just in degree but in kind from the abrogation of particular rights, duties or rules derived from EU law. It will constitute as significant a constitutional change as that which occurred when EU law was first incorporated in domestic law by the 1972 Act. And, if Notice is given, this change will occur irrespective of whether Parliament repeals the 1972 Act. It would be inconsistent with long-standing and fundamental principle for such a far reaching change to the UK constitutional arrangements to be brought about by ministerial decision or ministerial action alone. All the more so when the source in question was brought into existence by Parliament through primary legislation....

82..... The question is whether that domestic starting point, introduced by Parliament, can be set aside, or could have been intended to be set aside, by a decision of the UK executive without express Parliamentary authorisation. We cannot accept that a major change to UK constitutional arrangements can be achieved by ministers alone; it must be effected in the only way that the UK constitution recognises, namely by Parliamentary legislation. This conclusion appears to us to follow from the ordinary application of basic concepts of constitutional law to the present issue.....

90 The EU Treaties as implemented pursuant to the 1972 Act were and are unique in their legislative and constitutional implications. In 1972, for the first time in the history of the United Kingdom, a dynamic, international source of law was grafted onto, and above, the well-established existing sources of domestic law: Parliament and the courts. And, as explained in paras 13-15 above, before (i) signing and (ii) ratifying the 1972 Accession Treaty, ministers, acting internationally, waited for Parliament, acting domestically, (i) to give clear, if not legally binding, approval in the form of resolutions, and (ii) to enable the Treaty to be effective by passing the 1972 Act. Bearing in mind this unique history and the constitutional principle of Parliamentary sovereignty, it seems most improbable that those two parties had the intention or expectation that ministers, constitutionally the junior *646 partner in that exercise, could subsequently remove the graft without formal appropriate sanction from the constitutionally senior partner in that exercise, Parliament.....

Legislation and events after 1972: the 2015 Act and the referendum

116 We turn to the 2015 Act and the ensuing referendum. The Attorney General submitted that the traditional view as to the limits of prerogative power should not apply to a ministerial decision authorised by a majority of the members of the electorate who vote in a referendum provided for by Parliament. In effect, he said that, even though it was Parliament which required the referendum, the response to the referendum result should be a matter for ministers, and that it should not be constrained by the legal limitations which would have applied in the absence of the referendum.

117 The referendum is a relatively new feature of UK constitutional practice. There have been three national referendums: on EEC membership in 1975, on the Parliamentary election voting system in 2011 and on EU membership in 2016. There have also been referendums about devolution in Scotland, Wales and Northern Ireland and about independence in Scotland.....

118 The effect of any particular referendum must depend on the terms of the statute which authorises it. Further, legislation authorising a referendum more often than not has provided for the consequences on the result. Thus, the authorising statute may enact a change in the law subject to the proviso that it is not to come into effect unless approved by a majority in the referendum. The Scotland Act 1978 provided for devolution, but stipulated that the minister should bring the Act into force if there was a specified majority in a referendum, and if there was not he was required to lay an order repealing the Act. The Parliamentary Voting System and Constituencies Act 2011 had a provision requiring the alternative vote system to be adopted in Parliamentary elections, but by section 8 stated that the minister should bring this provision into force if it was approved in a referendum, but, if it was not, he should repeal it. Section 1 of the Northern Ireland Act 1998 ("the NI Act") provided that if a referendum were to result in a majority for the province to become part of a united Ireland, the Secretary of State should lay appropriate proposals before Parliament.

119 All these statutes stipulated what should happen in response to the referendum result, and what changes in the law were to follow, and how they were to be effected. The same is true of the provisions in Part 1 of the 2011 Act. By contrast, neither the 1975 Act nor the 2015 Act, which authorised referendums about membership of the European Community or European Union, made provision for any consequences of either possible outcome. They provided only that the referendum should be held, and they did so in substantially identical terms. The way in which the proposed *653 referendum was described in public statements by ministers, however, differed in the two cases. The 1975 referendum was described by ministers as advisory, whereas the 2016 referendum was described as advisory by some ministers and as decisive by others, but nothing hangs on that for present purposes. Whether or not they are clear and consistent, such public observations, wherever they are made, are not law: they are statements of political intention. Further, such statements are, at least normally, made by ministers on behalf of the UK government, not on behalf of Parliament.

120 It was suggested on behalf of the Secretary of State that, having referred the question whether to leave or remain to the electorate, Parliament cannot have intended that, upon the electorate voting to leave, the same question would be referred straight back to it. There are two problems with this argument. The first is that it assumes what it seeks to prove, namely that the referendum was intended by Parliament to have a legal effect as well as a political effect. The second problem is that the notion that Parliament would not envisage both a referendum and legislation being required to approve the same step is falsified by sections 2, 3 and 6 of the 2011 Act, which, as the Explanatory Notes (quoted in para 111 above) acknowledge, required just that-albeit in the more elegant way of stipulating for legislation whose effectiveness was conditional upon a concurring vote in a referendum.

121 Where, as in this case, implementation of a referendum result requires a change in the law of the land, and statute has not provided for that change, the change in the law must be made in the only way in which the UK constitution permits, namely through Parliamentary legislation.......

The Sewel Convention and question (ii)

136 That leaves the second question, which raises in substance the application of the Sewel Convention . The convention was adopted as a means of establishing co-operative relationships between the UK Parliament and the devolved institutions, where there were overlapping legislative competences. In each of the devolution settlements the UK Parliament has preserved its right to legislate on matters which are within the competence of the devolved legislature.......

137 The practical benefits of achieving harmony between legislatures in areas of competing competence, of avoiding duplication of effort, of enabling the UK Parliament to make UK-wide legislation where appropriate, such as establishing a single UK implementing body, and of avoiding any risk of legal challenge to the vires of the devolved legislatures were recognised from an early date in the devolution process. The convention takes its name from Lord Sewel, the Minister of State in the Scotland Office in the House of Lords who was responsible for the progress of the Scotland Bill in 1998. In a debate in the House of Lords (Hansard (HL Debates), 21 July 1998, col 791) on the clause which is now section 28 of the Scotland Act 1998 , he stated in July 1998 that, while the devolution of legislative competence did not affect the ability of the UK Parliament to legislate for Scotland, "we would expect a convention to be established that Westminster would not normally legislate with regard to devolved matters in Scotland without the consent of the Scottish Parliament". That expectation has been fulfilled......

141 Before addressing the more recent legislative recognition of the convention, it is necessary to consider the role of the courts in relation to constitutional conventions. It is well established that the courts of law cannot enforce a political convention....

146 Judges therefore are neither the parents nor the guardians of political conventions; they are merely observers. As such, they can recognise the operation of a political convention in the context of deciding a legal question (as in the Crossman diaries case- Attorney General v Jonathan Cape Ltd [1976] QB 752 ), but they cannot give legal rulings on its operation or scope, because those matters are determined within the political world. As Professor Colin Munro has stated (1975) 91 LQR 218, 228, "the validity of conventions cannot be the subject of proceedings in a court of law".

147 The evolving nature of devolution has resulted in the Sewel Convention also receiving statutory recognition through section 2 of the Scotland Act 2016 , which inserted subsection (8) into section 28 of the Scotland Act 1998 (which empowers the Scottish Parliament to make laws). Thus subsections (7) and (8) now state:

"(7) This section does not affect the power of the Parliament of the United Kingdom to make laws for Scotland.

"(8) But it is recognised that the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the consent of the Scottish Parliament."

A substantially identical provision (clause 2) is proposed in the Wales Bill 2016-2017, which is currently before the UK Parliament.

148 As the Advocate General submitted, by such provisions, the UK Parliament is not seeking to convert the Sewel Convention into a rule which can be interpreted, let alone enforced, by the courts; rather, it is recognising *660 the convention for what it is, namely a political convention, and is effectively declaring that it is a permanent feature of the relevant devolution settlement. That follows from the nature of the content, and is acknowledged by the words ("it is recognised" and "will not normally"), of the relevant subsection. We would have expected UK Parliament to have used other words if it were seeking to convert a convention into a legal rule justiciable by the courts.

149 In the Scotland Act 2016 , the recognition of the Sewel Convention occurs alongside the provision in section 1 of that Act. That section, by inserting section 63A into the Scotland Act 1998 , makes the Scottish Parliament and the Scottish government a permanent part of the United Kingdom's constitutional arrangements, signifies the commitment of the UK Parliament and government to those devolved institutions, and declares that those institutions are not to be abolished except on the basis of a decision of the people of Scotland voting in a referendum. This context supports our view that the purpose of the legislative recognition of the convention was to entrench it as a convention....

151 In reaching this conclusion we do not underestimate the importance of constitutional conventions, some of which play a fundamental role in the operation of our constitution. The Sewel Convention has an important role in facilitating harmonious relationships between the UK Parliament and the devolved legislatures. But the policing of its scope and the manner of its operation does not lie within the constitutional remit of the judiciary, which is to protect the rule of law.....