By Lisa Burton Crawford and Patrick Emerton

In June 2016, a referendum was held in the United Kingdom, asking the people whether they should remain a member of the European Union, or leave. A majority voted to leave. The result has sent shockwaves through the UK and the rest of Europe which continue to reverberate, not least in the decision of the UK Supreme Court handed down yesterday.

In R (on the application of Miller and Dos Santos) v Secretary of State for Exiting the European Union, the Supreme Court upheld the decision of the High Court before it, and concluded (by a majority of 8-3) that UK government ministers cannot give notice under Article 50 of Treaty of the European Union, and hence cannot trigger ‘Brexit’, without statutory authorisation. In other words, there is no non-statutory or ‘prerogative’ power to trigger Brexit. However, the Court unanimously held that the UK Parliament is not required to consult with or obtain the consent of the devolved legislatures of Scotland, Northern Ireland and Wales. The following is a brief summary of the key points of the majority decision. It does not profess to all explain all aspects of the judgment, and especially not the conclusions of the Court with regards to devolution.

In certain respects, the decision seems uncontroversial: it endorses many orthodox principles of UK constitutional law. Yet, the reasoning employed by the Supreme Court and the High Court before does raise interesting questions about the proper interpretation of statutes (including so-called ‘constitutional statutes’) and the place of EU law within the UK legal system — the answers to which are not necessarily straightforward.

The majority states that: ‘Parliamentary sovereignty is a fundamental principle of the UK constitution … Parliament has “the right to make or unmake any law whatsoever; and further, … no person or body is recognised by the law of England as having a right to override or set aside the legislation of Parliament”‘ (at [43]). Of course, this is consistent with the arguments put by our own Jeff Goldsworthy, who has long defended the doctrine of parliamentary sovereignty against those who argue that it is wrong, or else can be overturned by judges. On that latter note, the majority states: ‘it is not open to judges to apply or develop the common law in a way which is inconsistent with the law as laid down in or under statutes.’ (at [42]) Accordingly, the majority states that, while the executive enjoys certain prerogative powers, it cannot use those powers in a way that is inconsistent with legislation, or otherwise change or override the law. This has been the accepted position since the 17th century (see eg. [45]-[50]). Pertinently, the executive has prerogative power to enter into and withdraw from treaties — but this does not, and cannot, change domestic law.

The key statute in issue in this case is the European Communities Act 1972 (UK) (‘EC Act’), s 2(1) of which provides that: ‘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 …’  It was common ground that giving notice under Article 50 would change the law, including by removing rights conferred by this statute. It was also common ground that the legislation enacted to facilitate the Brexit referendum (although of great political significance) did not empower executive Ministers to make that change. While it would have been open to the sovereign Parliament to empower executive Ministers to give notice under Article 50 (and hence change the law), clear words to that effect would be required. The EC Act did not confer any such power (see [87]-[88]).

As noted at the outset, the principles articulated by the majority are not controversial, though people have debated how they ought to have been applied in this case, and Lords Reed, Carnwath and Hughes dissented. More interesting, we suggest, is the attitude towards the UK’s membership of the EU implicit in the majority’s reasoning.

The majority describe the EC Act as ‘the “conduit pipe” by which EU law is introduced into UK domestic law.’ ([65]) More importantly, the EC Act made EU institutions a source of EU law ([65]) — and so it ‘provided a new constitutional process for making law in the United Kingdom.’ ([62]) As a result of this Act together with the EU Treaty, ‘a dynamic, international source of law was grafted onto, and above, the well-established existing sources of domestic law: Parliament and the courts.’ ([90]) Thus the act of giving notice under Article 50 will not merely change the law, but also the constitutional arrangements that determine how law is made ([78]). So, while the Court properly refrained from commenting on the wisdom or otherwise of Brexit, the majority’s reasoning emphasises the fundamental integration of EU and UK law and legal institutions — and hence the enormity of the UK exiting the union.

So read, the judgment represents a striking extension of traditional UK constitutional ideas to the novel institutional arrangements of the European Union. Though the majority clearly endorse long-standing constitutional principles, they also emphasise the fluidity of the UK constitutional structure ([40]): as Dicey described it, in terms quoted by the majority, the UK is ‘the most flexible polity in existence’ ([40]). If we accept the majority judges’ view, the enactment of the EC Act, together with UK’s entry into the Treaty of the European Union, changed the constitutional structure of the UK. When the UK exits the EU (pursuant, we now know, to an act of Parliament), that structure will change again. This reminds us of — potentially, increasingly —differences between the UK and Australia, where constitutional change can only be effected by referendum.

Dr Lisa Burton Crawford is a Lecturer in the Monash Law Faculty. Dr Patrick Emerton is an Associate-Professor in the Monash Law Faculty and an Associate of the Castan Centre for Human Rights Law.

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