Notes from a Public Lecture delivered at the University Panthéon-Assas (Paris-II) 27 January 2017
Au lendemain de la victoire du Brexit, le problème de la détermination de l’autorité compétente pour enclencher la procédure de retrait de l’Union européenne s’est posé. L’article 50 du Traité sur l’Union européenne laisse au droit constitutionnel des Etats membres, le soin de déterminer les modalités de cette décision. C’est donc dans le cadre du droit constitutionnel britannique que doit être tranchée la question. Or, deux thèses s’opposèrent : l’une conférant ce pouvoir au Gouvernement, dans le cadre des Prérogatives de la Couronne ; l’autre exigeant une loi du Parlement.
Les juridictions britanniques ont été saisies de la question. Le 3 novembre 2016, dans une décision Miller commentée sur ce blog par Aurélien Antoine et Thibault Guilluy, la High Court of Justice, a jugé en première instance que cette décision relevait du Parlement. Le 24 janvier 2017, la Supreme Court of the United Kingdom (UKSC) a confirmé cette décision en appel. Les principales formules de l’arrêt de la UKSC ont été traduites par D. Baranger sur notre blog.
Quelques jours après cette décision, l’Institut Michel Villey a reçu Nicholas Aroney (professeur de droit constitutionnel à l’Université de Queensland, et actuellement professeur invité à l’Université Paris-II Panthéon-Assas) pour une conférence consacrée à l’arrêt Miller de la UKSC. Le texte en est reproduit ci-dessous. Le professeur australien y propose une analyse très serrée et judicieuse de cet arrêt qui est l’un des plus importants rendus par cette haute juridiction en matière constitutionnelle.
Article 50 of the Treaty on European Union provides that a Member State which decides in accordance with its own constitutional requirements to withdraw from the Union shall notify the European Council of its intention to do so. The central question in the Brexit case concerned the requirements of British law for the giving of such notice under Article 50. Is the Queen—in effect, the Government of the day—able to give the Article 50 notice simply in exercise of the prerogatives of the Crown? Or must such notification first be approved by the Parliament? On 24 January 2017 the Supreme Court of the United Kingdom brought down its decision that parliamentary authorisation would be required.
According to the submissions of the parties, there were two competing principles at stake in the case. Put in their most simple form, the two principles were that (a) Ministers of the UK Government, exercising the prerogatives of the Crown, normally have the power to enter and withdraw from treaties and that (b) Ministers do not normally have the power to make changes to UK law. All of the members of the Supreme Court appeared to accept the validity of these two underlying principles, in one formulation or another. Two things need to be noted about them, however. Firstly, the United Kingdom follows the dualist theory of the relationship between international and domestic law. This means that when the UK enters a treaty, this only creates obligations at international law; no rights or duties will be created in domestic law unless the Parliament passes a statute implementing the treaty. Secondly, both principles are subject to any Act of the Parliament that provides to the contrary. Thus, the power of Ministers to enter and withdraw from treaties can be controlled, qualified, replaced or abrogated by the Parliament; and Parliament can authorise Ministers to exercise powers that result in changes to UK law.
Unless affected by statute, therefore, the giving of notice under an international treaty such as Article 50 of the TEU, would ordinarily fall within the prerogatives of the Crown, exercisable by UK Ministers.
Accordingly, the question in the Brexit case became whether this power to give notice was qualified, either because a statute prohibited the UK Government from doing so, or because to do so would have had the effect of changing UK law established by statute. Two answers could be given to these questions, depending on whether one started with the first or the second of the two competing principles. This resulted in two lines of argument, which may be reconstructed into the form of two competing syllogisms. 
Major Premise A: The Crown has the prerogative power to give notice under Article 50, unless this is abrogated or regulated (expressly or impliedly) by Act of Parliament.
Minor Premise A: No Act of Parliament expressly or impliedly abrogates or regulates the Crown’s prerogative power to give notice under Article 50.
Conclusion A: The Crown has the [unabrogated and unregulated] prerogative power to give notice under Article 50.
Major Premise B: The Crown cannot exercise its prerogative powers to change the law or abrogate rights enacted by Parliament, unless this is authorised by Act of Parliament.
Minor Premise B1: The laws and rights created by or under the European treaties and given domestic effect by Acts of Parliament are laws and rights enacted by Parliament.
Minor Premise B2: An exercise by the Crown of power to give notice under Article 50 would change the law and abrogate the rights created by or under the European treaties and given domestic effect by Acts of Parliament.
Minor Premise B3: No Act of Parliament authorises the Crown to exercise its prerogative power to give notice under Article 50.
Conclusion B: The Crown cannot exercise its prerogative powers to give notice under Article 50 and thereby change the law and abrogate the rights created by or under the European treaties and given domestic effect by Acts of Parliament without authorisation by Act of Parliament.
Assuming the premises to be correct, both syllogisms are logically compelling. So, most of the argument in the case was directed to the validity of the premises. The validity of the major premises largely turned the Court’s interpretation of the relevant case-law, while the validity of the minor premises largely turned on the Court’s construction of the relevant statutes. The Government argued for the premises of Syllogism A and against those of Syllogism B while the Applicants argued for the premises of Syllogism B and against those of Syllogism A. However, because Major Premise A and Major Premise B, as well as Minor Premise A and Minor Premise B3, are not logically contradictory propositions, it remained possible, at least in theory, that both syllogisms were valid. This possibility made it necessary to consider which of the two major premises would prevail over the other in such an event.
The Brexit case came before the UK Supreme Court as an appeal from a decision of the Divisional Court of England and Wales and the reference of devolution issues for resolution following a decision of the Northern Ireland High Court. In essence, the latter court considered that the Syllogism A applied and governed the case, and concluded that the provisions of the Northern Ireland Act 1998 did not displace the Crown’s prerogative power to give notice under Article 50, while the former denied that Syllogism A applied, deciding instead that Syllogism B applied, with the result that, in the absence of an authorising statute, the Secretary of State does not have power under the Crown’s prerogative to give notice under Article 50..
By a majority of 8 to 3, the Supreme Court upheld the decision of the Divisional Court, with the result that UK Ministers, acting in the name of the Crown, cannot give notice under Article 50 without authorisation by Act of Parliament. However, the Supreme Court’s reasoning did not involve a simple application of Syllogism B. Or, at least, the application of the syllogism proved to be more complex and difficult than might have been expected. In a single paragraph embedded in the middle of the judgment the majority said that the Divisional Court had been correct to hold that ‘changes in domestic rights’ represented ‘another, albeit related, ground’ for justifying the conclusion that prerogative powers cannot be invoked to give notice to withdraw from the EU treaties without parliamentary approval. The main thrust of the reasoning of the majority, extending over several paragraphs in the judgment, focused on a more fundamental and far-reaching argument than this.
Why did the majority adopt an argument that was not specifically advanced by the parties? It seems that this was because the Applicants faced problems in establishing their argument that were not fully recognised by the Divisional Court. To understand these difficulties, and the alternative argument upon which the Supreme Court grounded its decision, it is necessary to review the several statutes enacted by the UK Parliament that deal with the UK’s membership, initially of the European Communities, and later of the European Union.
II. Statutory Background
The most important of the statutes that deal with the UK’s membership of the EC/EU is the European Communities Act 1972. The primary purpose of the Act was to ensure that the provisions of the European Community treaties and European laws created pursuant to those treaties would have direct effect in British law. This was necessary because the United Kingdom adheres to the dualist theory of the relationship between international and domestic law: ratification of a treaty creates rights and duties in international law, but a statute is required to translate those rights and duties into domestic law. The European Communities Act achieved this by providing that every provision of the treaties which was meant to be given direct effect in the Member States would be given that effect in UK law. When it was enacted, the Act named all of the then existing treaties. Over time, as new treaties were entered into by the Member States, the Act was amended to ensure that every relevant treaty which the UK signed would be given effect in this way.
The UK Parliament also enacted the European Assembly Elections Act 1978 and European Parliamentary Elections Act 2002, which gave British citizens rights to vote in elections and to stand as candidates for the European Assembly, or later, the European Parliament. Significantly, the two Acts provided that no treaty that provided for any increase in the powers of the European Assembly or Parliament shall be ratified unless it had been approved by an Act of the UK Parliament. The European Union (Amendment Act) 2008, which added the Treaty of Lisbon to the list of treaties in the European Communities Act, went further. It provided that statutory approval would be required prior to ratification of any treaty which amended the Treaty on European Union or the Treaty on the Functioning of the European Union by, in effect, altering the competences of the European Union, or which altered the decision-making processes of the European Union or its institutions so as to dilute the influence of individual Member States. And the European Union Act 2011 went even further still. It placed a complex set of controls on the ratification of amending treaties and on the UK’s approval of revisions to the treaties under the simplified revision procedure under Article 48(6) of the TEU. It required, in effect, that changes that would, among other things, increase the competences of the EU or result in a dilution in the influence of individual Member States would have to be first approved in a UK-wide referendum.
Finally, the Parliament enacted the European Union Referendum Act 2015. This Act authorised the holding of the referendum that was held in on 23 June 2016. However, it did not stipulate what the legal consequences of the referendum result would be. What would happen after the referendum was left to political determination.
III. Difficulties with Syllogism B
Given this statutory background, there were several difficulties with the Applicant’s arguments. The first concerned Syllogism A. For it is undoubted that the prerogative includes the power to conclude and withdraw from international treaties. The majority in the Supreme Court therefore readily accepted Major Premise A. The further problem, however, concerned Minor Premise A. For the European Communities Act in no place explicitly addresses—let alone abrogates or regulates—the prerogatives of the Crown—either to enter the treaties or withdraw from them. And it is not easy to establish that the Act has this effect by necessary implication. Much depends on whether one takes a narrow or broad approach to the discernment of implications. Thus, the High Court in McCord adopted statements in Morgan Grenfell and De Keyser that a necessary implication is not a ‘reasonable implication’, that the implication must ‘necessarily follow from the express provisions of the statute’ and that that the statute must ‘occupy the specific ground’ and must empower the doing of ‘the very thing’ previously occupied and undertaken by prerogative. While the European Communities Act assumes the existence of the treaties, it does not necessarily mandate their continued existence. And the Act certainly in no place addresses the prerogative to enter or withdraw from the treaties. In Miller the Divisional Court avoided the force of these arguments only by insisting that more weight should be given to the counter-principle that the Crown cannot use its prerogative powers to alter domestic law or remove rights, which was, in effect, to shift attention away from Syllogism A and towards Syllogism B.
For this reason, if Syllogism A were to govern the case, a decision in favour of the Government was rather likely. This gave the Applicants reason to direct their efforts towards Syllogism B in two respects: first, to establish that its major and minor premises were valid and, second, that Syllogism B, rather than Syllogism A, governed the case. But demonstrating the validity and priority of Syllogism B was not a simple matter either.
The Government’s attack on Major Premise B was not strong. It argued that the case-law does not support a general principle that the prerogative cannot be used to vary the law of the land or deprive individuals of rights and that cases had held, on the contrary, that the prerogative can be used to change domestic law and deprive individuals of rights. Notably, the reference here was to the changing of domestic law generally. However, the Applicant’s case depended on the more precise proposition that the prerogative cannot be used to defeat rights created by statute. It is difficult to see how this narrower proposition does not follow from the declaration in the Case of Proclamations that the King cannot change ‘any part of the common law, or statute law, or the customs of the realm’, or from the statement in The Zamora that, apart from delegated law-making power, the Executive has no power to prescribe or alter the law administered by the courts. The majority in the Supreme Court had no difficulty affirming the validity of Major Premise B and distinguishing situations where the exercise of the prerogative can affect the legal rights without changing the law.
The establishment of Minor Premise B1 was more difficult. The problem was with the unusual way in which the European Communities Act gave domestic effect to EU law. The Act was enacted after Britain signed the Treaty of Accession through which it would become a member of the European Communities but before Britain ratified it. This process recognised the capacity of the Government to sign the treaty in exercise of the Queen’s international prerogatives without parliamentary approval. But the timing also recognised the need to postpone Britain’s ratification of the treaty until after the European Communities Act came into force, to ensure that from the time of ratification Britain would be in compliance with its European obligations. This was achieved because the Act gave the required automatic and immediate domestic effect to the rights and duties created by the treaties or pursuant to them.
However, the s 2(1) of the Act doesn’t enact rights in any straight-forward sense. It rather assumes the existence of certain rights—rights ‘created or arising by or under the Treaties’—and it provides that these ‘shall be recognised and available in law, and be enforced’. And it refers to these rights as arising ‘from time to time’. Accordingly, it is not possible to know the content of the rights by reading the Act alone. The content of the rights depends on the treaties and on measures created by European institutions pursuant to those treaties. As such, the Act does not identify and does not control the content of the rights to which it gives domestic effect. Are such rights ‘enacted’ by the Parliament? Or, more to the point—bearing in mind the UK’s ‘dualist’ approach to the relationship between international and domestic law—are these rights properly within the sphere of the Parliament’s control over domestic law through the enactment of statutes, or are they properly within the sphere of the Government’s engagement in international affairs through the exercise of the prerogative? Because, if they are more in the nature of international rights, then their existence and their content would seem to depend on the Government’s engagement in international affairs, rather than the Parliament’s control over domestic law.
As Professor John Finnis argued, EU law and EU rights depend on two conditions for their existence—action by the Government on the international plane to make the UK a party to the treaties and a participating member of the EU, and action by the Parliament on the domestic plane to give EU rights domestic effect in UK law. On this view, it is within the jurisdiction of the Government both to enter such treaties and to withdraw from them. And this is no breach of the principle that the prerogative cannot be used to abrogate domestic law, because EU law is not domestic law, it is a special kind of international or, if you like, supranational law.
That was the problem with Minor Premise B1, and it proved to be a formidable one. For on close analysis it appears that the majority accepted that Minor Premise B1 could not be established. Echoing what they called the ‘illuminating analysis’ of Professor Finnis, the majority said that the ECA was only the ‘conduit pipe’ through which EU law is introduced into UK domestic law. For the EU institutions are the source of EU rights in UK law; it is they that create and abrogate the rights that apply domestically without the specific sanction of any UK institution; and accordingly the content of the EU rights is exclusively a matter of EU law, not domestic law.
But if this is so, then Syllogism B is invalid and Syllogism A should be dispositive of the case. For such an analysis suggests that the really vital factors—the source that creates and determines the content of the rights—occur on international plane, the sphere in which the prerogative normally operates. Indeed, this line of argument persuaded a minority of the Supreme Court to decide in favour of the Government (Lords Reed, Hughes and Carnwath). In order to avoid it, the majority had to devise a way around it.
IV. Constitutionalisation of the Arguments
What I want to suggest is that the majority avoided the difficulties posed by these problems with Syllogism B by circumventing the dualist account of the relationship between UK law and EU law. Now, of course, they did not explicitly reject dualism. In fact, they expressly affirmed it. Indeed, they said that dualism is the reason why the two fundamental propositions at stake in the case are compatible. For it explains why there is no contradiction between the powers of the Government and the powers of the Parliament in relation to the UK’s legal relationship to the EU—for the two powers operate in different spheres, one international, the other domestic.
However, from the perspective of dualism, the problem becomes this: from the perspective of which sphere of operation—domestic or international—is the act of giving notice under Article 50 to be understood? Given that the act of giving notice is (a) authorised by Article 50 and (b) ordinarily within the prerogatives of the Crown, dualism seems to lead to the conclusion that it is to be understood from the perspective of the UK’s relation to the international sphere, the sphere in which the Government’s international prerogatives operate. But if that is so, then Major Premise A seems to provide the relevant principle: the Government can through the exercise of the prerogative give notice under Article 50.
So the majority had to find some way around this to conclude, to the contrary, that Parliamentary approval would be required. They did this by emphasising the constitutionally ‘unprecedented’ and ‘exceptional’ nature of the system that the European Communities Act inaugurated. In particular, they not only said that the EU treaties and institutions are the source of the rights to which the ECA gives domestic effect, but that through that Act, the EU treaties and institutions themselves became a ‘direct source of UK law’, indeed, an ‘independent and overriding source of domestic law’, a source of law that ‘takes precedence over all domestic sources of UK law, including statutes’.
The constitutional novelty of the scheme introduced by the ECA did not, of course, transform the Act into some kind of ‘written constitution’ or ‘higher law’ that cannot be amended by the legislature. For the majority insisted that the basic constitutional principle of parliamentary sovereignty was not disturbed: the ECA could still be amended or repealed by the Parliament. Rather, the Act has a ‘constitutional character,’ they said, because the ‘fundamental’ reality of the new system inaugurated by the Act is that it introduces a new source of law into UK domestic law that takes precedence over domestic law, including parliamentary statutes, even those enacted in the future. The constitutional novelty of the new scheme was that it took rules that would ‘normally be incompatible with UK constitutional principles’ and made them ‘part of our constitutional arrangements’.
This move of bringing EU law-making into the framework of UK law was very important. For it moved the question from the domain of international law into the domain of domestic law—the domain in which Parliamentary sovereignty, rather than the international prerogatives of the Crown, operates. On this basis the majority insisted that, although the content of EU law is exclusively a question of EU law, this ‘new constitutional process for making law in the United Kingdom’ created by the ECA was to be understood, not from the perspective of the UK’s relationship to EU law or international law, but from the perspective of the domestic domain of UK law.
This was very clever. Analysing it this way, the majority were able to acknowledge that the operation of EU law in the United Kingdom is dependent on two conditions: the UK’s adherence to the EU treaties and implementation of those treaties by UK statute. But by characterising the question as ‘constitutional’ in this special sense, they were able to conclude that the giving of notice under Article 50, although an act of the prerogative operating in the ‘international’ domain, fell to be determined by reference to the sphere of domestic law, where the principle of parliamentary sovereignty prevails.
According to the majority, this entailed the consequence that the prerogative could not be used to make ‘fundamental change[s] to the constitutional arrangements of the United Kingdom’ without parliamentary approval. It also enabled the majority to explain why Major Premise A was inapplicable to the case at hand. For on this view the EU treaties ‘not only concern international relations’ but they ‘are a source of domestic law … and domestic rights’. As a result they have become part of domestic law, and have transformed that domestic law by integrating it with the EU system of law. And because the EU treaties have this organic relationship to domestic law—because they are now constituent elements of the UK constitution—the UK cannot withdraw from them simply by an exercise of the prerogative. Parliamentary authorisation is required for a far-reaching constitutional change of this kind.
This was a novel line of reasoning. For although the Divisional Court and the Applicants also drew attention to the constitutional character of the scheme created by the ECA, and the introduction of EU treaties and institutions as new sources of law involving new law-making processes, the basic structure and content of Syllogism B, with its focus on ‘rights’ and the alteration of the ‘law’, and the need to rebut Syllogism A, remained central to their arguments.
It was also a breath-taking line of reasoning. For, viewed in this way, what the Government needed to show, was not only that no statute had (negatively) removed or fettered the prerogative, but also that a statute had (positively) conferred it. But as the ECA never addressed the question, it was nigh impossible to show the latter to be the case. Indeed, applying the principle of ‘legality’, the majority said that the statute would only be interpreted to have the effect of enabling the prerogative to be used to abrogate EU rights in clear and express terms. The silence of the ECA on the question of the prerogative was thus turned against the Government.
IV. European Federalism
The line of reasoning adopted by the majority, although grounded on the principle of parliamentary sovereignty, turns not simply on the well-established traditions of UK constitutional law, but recapitulates in a UK context the unique and unprecedented nature of the European Union as a kind of constitutional order and supranational system of government that is nonetheless founded on a series of international treaties.
This remarkable character of the European Union sets it apart from ordinary international organisations on one hand and ordinary unitary states on the other. A unitary state rests, according to a certain kind of liberal-democratic theory, on a hypothesised social contract entered into by a particular group of people. While the theory proposes that, conceptually, every individual person consents to the formation of the political community, once the community is formed, its typical mode of making decisions is by majority vote. At the other end of the spectrum, an international organisation is formed by a treaty between independent states. The basic decision-making rule is on of unanimity. Each and every member state individually agrees to the formation of the international organisation and participates in its decision-making on an equal basis.
The EU has this latter quality. It was formed by the agreement of each Member State and every amending treaty has required the unanimous consent of every state. EU laws may be made through processes that involve rule by qualified majorities, but that is because the Member States first agreed to the establishment of such a system. Integrative federations and confederations also have this quality. They are classically formed by the agreement of each and every member state, but they provide in their constitutions for law-making processes that depend on majority rule. And in both the EU and classic federations, the laws of the ‘union’ have direct effect within the member states and operate notwithstanding anything in the law of the member state to the contrary.
But that is not the whole of the picture. It is also important to look at the special decision-making rules that are adopted for the amendment of the founding document of the political system, and for the withdrawal of member states from it. International organisations and confederations—and the EU falls into this category in this respect—typically provide that for the amendment of the arrangement the consent of every member state is required. And while it was a matter of dispute for a long time, the Lisbon Treaty has further provided that each member state has, in effect, a unilateral right to withdraw from the EU—subject of course to the conditions laid down in Article 50.
Similar claims are routinely made in confederations: that each member state entered the confederation by the exercise of its own will, and it retains the right to judge whether the other parties have fulfilled their obligations under the confederation, and it retains the unilateral right to withdraw from the confederation if it judges that this is the appropriate action to take. Indeed, the very same claim was made by the secessionist states of the United States of America in the period leading up to the civil war, and it was also made by the secessionist cantons of Switzerland in 1947. However, both the United States and Switzerland are considered to be ‘federations’, not ‘confederations’. What makes them ‘federations’ is, in part, a result of real-politik: the forces of the centre compelled the secessionist states to remain part of the union. However, when one looks at the amendment formulas in the constitutions of federations, they are very different from what one sees in Article 50 of the TEU. While federal constitutions cannot usually be amended by a simple majority of the people, nor do these constitutions require the unanimous consent of all of the member states. This is what makes a federation different from a confederation. Both are founded on the unanimous consent of the member states. But in confederations the rule of unanimity is retained for the amendment of the constitution, whereas in federations the rule some form of qualified majority—albeit a majority of states, certainly not a simple majority of the people of the federation as a whole.
Understood in this context, the EU looks a lot like a confederation.
V. Alternative Perspectives
But this analysis raises an important question. When a federal-like political system is formed, when it is amended, and when a member state withdraws from membership, from the perspective of which system of law is the act of formation, the act of amendment and the act of withdrawal to be regulated? For, as has been argued, it was this question that lay at the heart of the Brexit case. Although Article 50 pointedly says that each member state determines whether it intends to withdraw ‘in accordance with its own constitution’, when the majority of the Supreme Court sought to identify the requirements of UK law for the giving of notice under Article 50, they cleverly circumvented the dualist theory of the UK’s relationship to the EU under which the exercise of the prerogative operates on the plain of international law while the parliament enacts law to give domestic effect to the UK’s international obligations. The majority bypassed this by saying, in effect, that the ECA incorporated the UK into a unique supranational constitutional system in which the barriers between domestic and international law are broken down. Thus they said that EU law-making institutions have become sources of UK domestic law, and by becoming part of domestic law they have, in turn, transformed it by integrating it with the EU system of law. There is an organic relationship between EU law and UK law because EU law-making institutions have become constituent elements of the UK constitution. As the majority put it: ‘a dynamic, international source of law was grafted onto, and above, the well-established existing sources of domestic law’.
Thus, while the UK constitution was not changed, it was changed. That is the intriguing paradox of the Supreme Court’s decision in the Brexit case. And interestingly, much the same issue was at stake in the ‘transformation’ of the US federation after the civil war, from a federation in which each state exercised its own judgment about the constitutional validity of federal action, to a federation in which the judgments of the federal institutions of government—the President, the Congress and the Supreme—always prevail, at least ultimately so.
So what conclusions can we draw from all this? The first is that very complex and fascinating issues arise when federations and special international organisations, like the EU, are brought into existence. Conflicts emerge over the meaning and interpretation of the relevant instruments (‘treaties’ or ‘constitutions’) that establish the arrangement, and deep questions arise about which system of law, and from which institutional perspective, judgments are to be made and actions are to be taken.
Article 50 shows that the EU treaties not only recognise the unilateral right of each member state to withdraw from the Union, but that the legal processes by which any such decision to withdraw is determined is a question for the domestic constitutional law of the Member State and not the constitutional law of the European Union. However, the majority’s decision in the Brexit case seems to have turned this on its head in subtle ways. For in their reasoning, when the UK enacted the ECA it brought EU law-making into UK domestic law, not only at the level of the specific rules and remedies of EU law, but at a constitutional level as well.
VI. Alternative Syllogisms
As I said, this is a breath-taking conclusion. Whether it is the right conclusion, or whether the dissenting judges more faithfully decided the case ‘in accordance with the constitutional requirements of United Kingdom’—as Article 50 requires—is something we should ponder.
In pondering it, it may be helpful to put the reasoning of the majority into the form of a new syllogism:
Major Premise C: The Crown cannot exercise its prerogative powers to change the constitution of the United Kingdom or abrogate sources of domestic law created by Act of Parliament, unless this is authorised by Act of Parliament.
Minor Premise C1: The European Communities Act makes provision for an aspect of the constitution of the United Kingdom by creating a new source of law in UK domestic law.
Minor Premise C2: An exercise by the Crown of the prerogative power to give notice under Article 50 would change the constitution of the United Kingdom by abrogating a source of domestic law created by Act of Parliament.
Minor Premise C3: No Act of Parliament authorises the Crown to exercise its prerogative power to give notice under Article 50.
Conclusion C: The Crown cannot exercise its prerogative powers to give notice under Article 50 and change the constitution of the United Kingdom by abrogating a source of domestic law created by Act of Parliament without authorisation by Act of Parliament.
 R (Miller) v Secretary of State for Exiting the European Union  UKSC 5 (24 January 2017) (Lord Neuberger, Lady Hale, Lord Mance, Lord Kerr, Lord Clarke, Lord Wilson, Lord Sumption and Lord Hodge; Lord Reed, Lord Carnwath and Lord Hughes dissenting) (hereafter ‘Miller (SC)’).
 Ibid  (Lord Neuberger, Lady Hale, Lord Mance, Lord Kerr, Lord Clarke, Lord Wilson, Lord Sumption, Lord Hodge),  (Lord Reed),  (Lord Carnwath) and  (Lord Hughes).
 For a discussion of the syllogisms in the case, see John Finnis, ‘Terminating Treaty-based UK Rights’, UK Constitutional Law Association (26 October 2016); Paul Craig, ‘Miller: Alternative Syllogisms’ Oxford Human Rights Hub (23 November 2016).
 It also meant that a large part of the case concerned whether, in terms of Minor Premise A and Minor Premise B3, the question was whether the relevant statutes negatively abrogate or positively authorise the Crown to exercise its prerogative power to give notice under Article 50.
 R (Miller) v Secretary of State for Exiting the European Union  EWHC 2768 (Admin) (3 November 2016) (Lord Thomas of Cwmgiedd LCJ, Sir Terence Etherton MR and Sales LJ) (hereafter ‘Miller (DC)’).
 Re McCord, Judicial Review  NIQB 85 (28 October 2016) (Maguire J) (hereafter ‘McCord (HC)’).
 McCord (HC) -.
 McCord (HC) -.
 Miller (DC) -, -.
 Miller (DC) -, -, -, -, . The Divisional Court’s affirmation of Syllogism B was expressed partly in its response to the contrary arguments of the Government (at -, -).
 Miller (DC) .
 Miller (SC) , .
 Miller (SC) . See also  (referring to the ‘arguments’ whether the giving of notice without statutory authority would ‘impermissibly result in a change to domestic law’), - (discussing the Divisional Court’s assessment of the rights that would be affected by withdrawal) and  (rejecting the Government’s response that prerogative powers can alter domestic law).
 It is in its discussion of the ‘arguments’ referred to in para  that the Supreme Court transforms those arguments into something more profound: see -. See also the Supreme Court’s consideration of the Government’s arguments -, especially at -,  and .
 Namely, the European Economic Community, the European Coal and Steel Community and the European Atomic Energy Community.
 European Communities Act, s 2(1). To be more precise, the sub-section states: ‘All such rights, powers, liabilities, obligations and restrictions from time to time created or arising by or under the Treaties, and all such remedies and procedures from time to time provided for by or under the Treaties, as in accordance with the Treaties are without further enactment to be given legal effect or used in the United Kingdom shall be recognised and available in law, and be enforced, allowed and followed accordingly; and the expression « enforceable Community right » and similar expressions shall be read as referring to one to which this subsection applies.’
 Certain ancillary treaties were also included by reference: European Communities Act 1972 (UK) s 1(1).
 European Assembly Elections Act 1978, s 6; European Parliamentary Elections Act 2002, s 12.
 This is the effect of the European Union (Amendment Act) 2008, s 5, as summarised by the Supreme Court at .
 This is the effect of the European Union Act 2011, ss 2-6, as summarised by the Supreme Court at .
 JH Rayner (Mincing Lane) Ltd v Department of Trade and Industry  2 AC 418, 476 (Lord Templeman): ‘[t]he Government may negotiate, conclude, construe, observe, breach, repudiate or terminate a treaty’.
 Miller (SC) -.
 McCord (HC) -, citing Lord Hobhouse in R (Morgan Grenfell & Co Ltd) v Special Commissioner of Income Tax  2 WLR 1299,  (emphasis added) and Attorney General v De Keysers’ Royal Hotels Ltd  AC 508, 526 (Lord Dunedin), 539 (Lord Atkinson). It was only the Acts of 1978, 2002, 2008 and 2011 that ever specifically addressed the exercise of the prerogative powers with respect to the UK’s entry into EU-related treaties. However, these Acts were deliberately limited to controlling the UK’s entry into treaties which, in particular, had the effect of either altering the competences of the EU or diluting the influence of Member States within the EU. Thus, on the occasion when the Parliament addressed its attention to the exercise of the prerogatives in this context, it chose not to place any restrictions on the power to give notice of a decision to withdraw from the EU under Article 50, even though this was one of the key features of the Treaty of Lisbon, to which the European Union (Amendment Act) 2008 gave effect.
 Miller (DC) -.
 Appellant’s Case (Miller (SC)) paras 54-60.
 Written Case for the Lead Claimant (Miller (SC)) para 2(3)(b).
 Case of Proclamations (1610) 12 Co Rep 74 (Sir Edward Coke CJ).
 The Zamora  2 AC 77, 90 (Lord Parker of Waddington). See also in JH Rayner (Mincing Lane) Ltd v Department of Trade and Industry  2 AC 418, 500 (Lord Oliver of Aylmerton).
 Miller (SC) -, .
 Miller (SC) -.
 John Finnis, ‘Terminating Treaty-based UK Rights’, UK Constitutional Law Association (26 October 2016).
 Miller (SC) .
 Miller (SC) -.
 Notably, the majority did call it ‘the so-called dualist theory’: at  (emphasis added), suggesting some degree of scepticism about it.
 Miller (SC) .
 Miller (SC) , , citing the famous decisions of the European Court of Justice, Van Gend en Loos (Case C-26/62)  ECR 1, 12 and Costa v ENEL (Case C-6/64)  ECR 585, 593.
 Miller (SC) .
 Miller (SC) , , . ‘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’: .
 Miller (SC)  (emphasis and words added). See also .
 Miller (SC) .
 Miller (SC) .
 The majority thus suggested a dual role for the Parliament: the image of the sovereign Parliament that enacted the European Communities Act and can amend or repeal that Act is combined with an image of the Parliament as a legislature that has submitted itself to EU law in the precise sense that its whose statutes operate subject to supervening EU law. This is a puzzle that arises in other areas of UK constitutional law, particularly in relation to the devolution statutes, where the UK Parliament operates simultaneously as the special legislature for England and Wales (alongside the special legislatures for Scotland, Wales and Norther Ireland), the general legislature for the entire United Kingdom, and the sovereign legislature that established the entire system of devolution. But for the Court in the Brexit case at least, the two ‘roles’ of Parliament are sublimated into the principle that while the European Communities Act and can be amended or repealed by a later Act that does so expressly, ‘EU law cannot be implicitly displaced by the mere enactment of legislation which is inconsistent with it’: Miller (SC) , citing s 2(4) of the Act and Factortame Ltd (No 2)  1 AC 603 and Thoburn v Sunderland City Council  QB 151, paras - (Laws LJ).
 Miller (SC)  (emphasis added).
 Miller (SC) .
 Miller (SC) -.
 Miller (SC) , -; see also . This was to go further than the Divisional Court had done: its decision had been based on the proposition that withdrawal would result in ‘changes in domestic rights’. As noted, the majority of the Supreme Court considered this to be ‘another, albeit related, ground’ for concluding that the prerogative powers cannot be used to withdraw from the EU treaties without parliamentary approval: .
 Miller (SC)  (emphasis added).
 Miller (SC) .
 Miller (DC) -, -; Written Case for the Lead Claimant (Miller (SC)) paras 2(1) (second sentence). Reflecting on what was said by the Divisional Court about the constitutional character of the ECA, the Applicants suggested that the reason why the ECA cannot be impliedly repealed is the same reason why the rights conferred by the ECA cannot be defeated by the use of prerogative powers: that such rights cannot be defeated without clear parliamentary authorisation (see para 41). But this was to rebut Syllogism A and support Syllogism B, not to construct an alternative syllogism altogether.
 Miller (DC) , .
 Miller (DC) -, , -, passim; Written Case for the Lead Claimant (Miller (SC)) paras 2(1) (first and third sentences), 2(2)-(3), 15-18, 21-33, 43. This is not to suggest that the Applicants did not recognise the need to overcome the implications of dualism (see para 2(4)(a)) by focusing on the exceptional nature of the ECA and the EU (see paras 4-6, 8).
 Miller (SC) .
 The majority considered, indeed, that the opposite was the case: that the better interpretation of the Act was that it positively denied that Ministers had the power to withdraw from the EU treaties: .
 Miller (SC) . This was to apply a test that is even more stringent than the ‘express or necessarily implied’ test that applies to the abrogation of the prerogative.
 Federations formed through devolutionary processes within an a formerly unitary state have a different character in these respects. See, further, Nicholas Aroney, ‘Types of Federalism’ in Rainer Grote, Frauke Lachenmann and Rüdiger Wolfrum (eds), Max Planck Encyclopedia of Comparative Constitutional Law (Oxford University Press, forthcoming 2017) [available at: https://ssrn.com/abstract=2783119].
 The ‘simplified revision procedures’ in Article 48(6) of the TEU are very limited in their operation compared the ‘ordinary revision procedures’ referred to in Art 48(2)-(5).
 Miller (SC) .