Sir Edward Coke’s bold assertion in 1605 of one of the cornerstones of the unwritten constitution of the United Kingdom has been upheld today in a hugely important decision by the Supreme Court. In R(Miller) v Secretary of the State for Exiting the European Union  UKSC 5, the Supreme Court today ruled 8-3 that an Act of Parliament was required to authorise ministers to give Notice of the decision of the UK to withdraw from the European Union. This post focuses on the decisions made in relation to the more legally significant claim that this Article 50 notice could not be given without Parliamentary approval, rather than those made in relation to the devolution claims – although in terms of practical political impact, a ruling that the devolved assemblies had to approve the giving of notice would have been far more disruptive to the Government’s plans.
Lord Neuberger, with whom Lady Hale, and Lords Mance, Kerr, Sumption, Clarke, Wilson and Hodge agreed), gave the judgment for the majority. He introduced the case by putting the issue very simply “The question before this Court concerns the steps which are required as a matter of UK domestic law before the process of leaving the European Union can be initiated.”
As Lord Hughes in dissent summarised, there were two conflicting rules – (1) the executive (government) cannot change law made by Act of Parliament, nor the common law and (2) the making and unmaking of treaties is a matter of foreign relations within the competence of the government.
In the words of Lord Hughes:
“ Mrs Miller’s case was that because there was an Act of Parliament (the European Communities Act 1972) to give effect to our joining the (then) EEC and to make European rules part of UK law, there has to be another Act of Parliament to authorise service of notice to leave. This is the effect, she says, of Rule 1. Thus, she says, Rule 2 is true, but does not apply.
 The government’s case is that the European Communities Act 1972, which did indeed make European rules into laws of the UK, will simply cease to operate if the UK leaves. The Act was only ever designed to have effect whilst we were members of the EU. It agrees that as a government it cannot alter the law of the UK which statute has made, but it says that if it serves notice to leave the EU, and in due course we leave, it would not be altering the statute; the statute would simply cease to apply because there would no longer be rules under treaties to which the UK was a party. Thus, it says, Rule 1 does not apply and Rule 2 does.”
Unsurprisingly in light of the vitriol already thrown at the Divisional Court (and doubtless to come towards the Supreme Court), Lord Neuberger was at pains to also preface his judgment by emphasising that:
“this case has nothing to do with issues such as the wisdom of the decision to withdraw from the European Union, the terms of withdrawal, the timetable or arrangements for withdrawal, or the details of any future relationship with the European Union. Those are all political issues which are matters for ministers and Parliament to resolve.”
Lord Neuberger began his substantive consideration of the case by examining the background and detailed wording of the European Communities Act 1972. He identified as ‘significant’ that “future treaties which were concerned with changing the membership or redefining the rules of the EEC could only become “Treaties” and “EU Treaties” and have effect in UK law as such if they were added to section 1(2) by an amending statute.” ‘Treaties’ gave rise to directly effective legal rights within the United Kingdom without further enactment.
Lord Neuberger stated that it was common ground that notice of withdrawal from the EU given under Article 50(2) of the Treaty of Lisbon could not be withdrawn once given, and that accordingly, once the United Kingdom gave Notice, it would inevitably cease at a later date to be a member of the European Union and a party to the EU Treaties.
Lord Neuberger then gave a whistlestop, but textbook constitutional history of the United Kingdom and the origins of the doctrine of Parliamentary sovereignty. He concluded that the:
“Crown’s administrative powers are now exercised by the executive, ie by ministers who are answerable to the UK Parliament. However, consistently with the principles established in the 17th century, the exercise of those powers must be compatible with legislation and the common law. Otherwise, ministers would be changing (or infringing) the law, which, as just explained, they cannot do…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…thus consistently with Parliamentary sovereignty, a prerogative power however well-established may be curtailed or abrogated by statute. Indeed… 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…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…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.”
With regards to the specific issue of the treaty making prerogative, Lord Neuberger held that:
“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…This principle rests on the so-called dualist theory, which is based on the proposition that international law and domestic law operate in independent spheres. The prerogative power to make treaties depends on two related propositions. The first is that treaties between sovereign states have effect in international law and are not governed by the domestic law of any state… The second proposition is that, although they are binding on the United Kingdom in international law, treaties are not part of UK law and give rise to no legal rights or obligations in domestic law… It is only on the basis of these two propositions that the exercise of the prerogative power to make and unmake treaties is consistent with the rule that ministers cannot alter UK domestic law.”
Having set out the legal background to the specific issues before the Court, Lord Neuberger considered the nature and status of the 1972 Act. He noted that 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.” He held 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,” and that the 1972 Act had provided for a new constitutional process for making law in the United Kingdom.
He concluded that:
“although the 1972 Act gives effect to EU law, it is not itself the originating source of that law. It is… 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… The primacy of EU law means that, unlike other rules of domestic law, EU law cannot be implicitly displaced by the mere enactment of legislation which is inconsistent with it…The 1972 Act accordingly has a constitutional character… However, legislation which alters the domestic constitutional status of EU institutions or of EU law is not constrained by the need to be consistent with EU law. In the case of such legislation, there is no question of EU law having primacy, so that such legislation will have domestic effect even if it infringes EU law (and that would be true whether or not the 1972 Act remained in force). That is because of the principle of Parliamentary sovereignty which is, as explained above, fundamental to the United Kingdom’s constitutional arrangements, and EU law can only enjoy a status in domestic law which that principle allows. It will therefore have that status only for as long as the 1972 Act continues to apply, and that, of course, can only be a matter for Parliament…The 1972 Act effectively operates as a partial transfer of law-making powers, or an assignment of legislative competences, by Parliament to the EU law-making institutions.”
Lord Neuberger then analysed the various rights that would be lost to UK citizens as a result of the UK’s exit from the EU, and concluded that it was clear that some rights (even if replicable in UK law) would be lost – for example, the rights of UK citizens to the benefit of employment protection under the Working Time Directive.
Lord Neuberger concluded on the key issue before the court that:
“we consider that, by the 1972 Act, Parliament endorsed and gave effect to the United Kingdom’s membership of what is now the European Union under the EU Treaties in a way which is inconsistent with the future exercise by ministers of any prerogative power to withdraw from such Treaties….In short, the fact that EU law will no longer be part of UK domestic law if the United Kingdom withdraws from the EU Treaties does not mean that Parliament contemplated or intended that ministers could cause the United Kingdom to withdraw from the EU Treaties without prior Parliamentary approval. There is a vital difference between changes in domestic law resulting from variations in the content of EU law arising from new EU legislation, and changes in domestic law resulting from withdrawal by the United Kingdom from the European Union. The former involves changes in EU law, which are then brought into domestic law through section 2 of the 1972 Act. The latter involves a unilateral action by the relevant constitutional bodies which effects a fundamental change in the constitutional arrangements of the United Kingdom…
One of the most fundamental functions of the constitution of any state is to identify the sources of its law…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… 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…
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, which gave that source an overriding supremacy in the hierarchy of domestic law sources…
[B]y the 1972 Act, Parliament endorsed and gave effect to the UK’s future membership of the European Union, and this became a fixed domestic starting point. 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 a 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.
[T]he EU Treaties not only concern the international relations of the United Kingdom, they are a source of domestic law, and they are a source of domestic legal rights many of which are inextricably linked with domestic law from other sources. Accordingly, the Royal prerogative to make and unmake treaties, which operates wholly on the international plane, cannot be exercised in relation to the EU Treaties, at least in the absence of domestic sanction in appropriate statutory form.”
Lord Neuberger went on to hold that the:
“improbability of the Secretary of State’s case is reinforced by the point that, if, as he contends, prerogative powers could be invoked in relation to the EU Treaties despite the provisions of the 1972 Act, it would have been open to ministers to take such a course on or at any time after 2 January 1973 without authorisation by Parliament. It would also follow that ministers could have taken that course even if there had been no referendum or indeed, at least in theory, even if any referendum had resulted in a vote to remain. Those are implausible propositions.”
Lord Neuberger also rejected arguments made by the Government founding on the various acts passed since 1972 concerning the relationship between the UK and the EU, holding that they were entirely consistent with an assumption by Parliament that no power existed to withdraw from the treaties without a statute authorising that course.
Lastly, with relation to the 2016 referendum, Lord Neuberger rejected the Government’s argument 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. He noted that the 2015 Referendum Act (unlike other acts authorising referendums) did not provide for the consequence of its two possible outcomes. He concluded that “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.”
One slim consolation for the Government was that Lord Neubergeralso held that “[w]hat form such legislation should take is entirely a matter for Parliament.”
This judgment will doubtless be seized on by many as another example of judicial activism, and inappropriate interference with the democratic result of the referendum. However, despite the minority judgments of Lords Reed and Hughes to the effect that the 1972 Act was only intended to have an effect for as long as the Government decided that the UK should be part of the EU, the majority judgment is rooted in a fundamental statement of the basic principles of parliamentary sovereignty and the limits on the executive – which aims ironically the Leave campaign sought to advance.