Public Law analysis: In its highly anticipated judgment in R (on the application of Miller and another) v Secretary of State for Exiting the European Union, the UK Supreme Court ruled (by majority) that an Act of Parliament is required to authorise the triggering of Article 50 TEU by the UK government. Our panel of experts considers what this means for the UK’s withdrawal from the EU, and also the wider legal, political and constitutional significance of the judgment.

The experts

• Katherine Apps (KA), barrister at Littleton Chambers
• Hazel Moffat (HM), partner at DLA Piper
• Charles Brasted (CB), partner, and Andrew Eaton (AE), associate, at Hogan Lovells
• Jamie Potter (JP), partner in Bindmans’ public law and human rights department

What is your initial assessment of the Supreme Court’s judgment?

KA: For the most part the judgment of the majority is not particularly surprising. The government had accepted that leaving the EU will directly change UK domestic law, and that the rights enjoyed by UK residents will be directly affected. The Supreme Court found that this direct impact on individual rights means that it is impossible for the government to withdraw from the EU Treaties without parliamentary authority. The challenges brought prior to the referendum by nonresident British citizens, who had no vote in the EU referendum, established that the referendum itself would have no impact on individual rights. This judgment is consistent with those cases.

The Supreme Court’s rejection of the devolution arguments is interesting. The Supreme Court held that the Sewel Convention, in Scotland, operates as a political restraint, but that policing it falls outside of the court’s remit. The Supreme Court also held that there is no separate requirement for the Northern Ireland legislature to have its say. The devolution statutes do not place responsibility for foreign affairs within the devolved legislatures’ powers—those remain in Westminster.

HM: This is the biggest constitutional case for a generation and is the first case to be heard by all eleven Supreme Court judges. Not surprisingly, the decision is very complete and considered although it is a clear defeat for the government with a ratio of eight to three judges agreeing that the UK Parliament will need to pass legislation in order to trigger Article 50 TEU. This is on the basis that while the government does have prerogative power to withdraw from international treaties, it cannot exercise  such power without an Act of Parliament if it would, in doing so, change UK laws. 

CB & AE: The claimants argued that an Act of Parliament was required to authorise the triggering of Article 50 TEU, and the Supreme Court has ruled (by a majority of eight to three) that they were right. 

The Supreme Court emphasised during the handing down of the judgment that the case had nothing to do with the political issues of Brexit, such as the merits of the decision to withdraw, the timetable for withdrawal, or the terms of any future relationship. However, as Lord Carnwath recognised in his dissenting judgment, it has provided an opportunity for the important legal issues at play to be brought before the UK courts at the beginning of the Brexit process—the detailed debate in the courts and the vigorous academic debate it has provoked will no doubt inform the process going forward.

It may surprise some that the question of whether an Article 50 notice could be revoked by the UK after the Brexit process has been triggered remains unanswered. The government expressly resisted this issue being ruled on, even though the Divisional Court noted that, if it could be revoked, the claim would be ‘blown out of the water’. The Supreme Court decided to make its ruling on the basis of an assumption that Article 50 TEU was irrevocable. Ultimately, whether this assumption is correct can only be determined by the Court of Justice of the European Union, and other claimants have already come forward seeking to have that question decided.JP: By a majority of eight to three, the Supreme Court upheld the Divisional Court ruling in favour of the claimants (the respondents in the appeal) that parliamentary authority is required before Article 50 TEU can be triggered, setting in motion the process for the UK to leave the EU.

In essence, the majority concluded that, through the European Communities Act 1972, Parliament had fundamentally changed UK law and granted rights to its citizens deriving from EU law. The triggering of Article 50 TEU would, in the view of the parties (the court did not actually determine whether Article 50 TEU was revocable), inevitably lead to a further significant change to UK law and the rights of its citizens, which required the authority of Parliament and could not be achieved through the use of prerogative powers (ie the historic powers vested in the monarchy, but now exercised in practice by the government of the day).

What does this mean for the government’s Brexit plan? 

KA: The government has already begun work drafting legislation to authorise the triggering of Article 50 TEU. It had been rumoured that the Labour leadership will instruct MPs to vote for it. It will be interesting to see how detailed this Bill is. Will it set out all of the rights which individuals will no longer have? I doubt it. Will it be a simple four-line Bill authorising the triggering of Article 50 TEU? Again, the political noises in the press suggest not. However, the simple fact is that, if the decision is taken to withdraw from the EU under the Article 50 TEU mechanism, any other steps are not within Parliament’s powers to mandate. They will all depend on achieving agreement from the EU. The government accepted expressly in arguments in the Supreme Court and Divisional Court that, once triggered, as a matter of EU law, Article 50 TEU could not be ‘un-triggered’. The Supreme Court did not consider whether the government would need separately to trigger withdrawal under the EEA Agreement. This question may rise to prominence in the weeks and months to come. 

HM: The result will be a blow to the UK government, but one for which it will have been preparing. However the extent of this blow has been limited. All Supreme Court judges unanimously agreed that there is no requirement to seek the consent of the devolved legislatures in this process which has, at least, removed one material political obstacle from the government’s path. The challenge for the government now will be to deliver on its plan to trigger Article 50 TEU and to start the UK’s exit negotiations from the EU—in March 2017.

Draft (alternative) versions of the Bill are thought to have been prepared already and it is expected that the Bill proposed will be extremely concise and focused in scope to help ensure that parliamentary debate and scope for amendment is as limited as possible. There has already been commentary from MPs that they fully intend to seek amendments to the Bill, including a suggestion from the SNP that their MPs will table 50 ‘serious and substantive’ amendments to the Bill including a demand that all three devolved governments must agree to triggering Article 50 TEU (despite the ruling). The Bill’s journey through the House of Lords is also expected to be bumpy and take longer, calling into question the deliverability of the government’s March timescale.

CB & AE: In practical terms, today’s judgment appears unlikely to affect the Prime Minister’s timetable for withdrawal, or her government’s objectives for Brexit. However, it does mean that the next step in the process of the UK’s withdrawal from the EU is for Parliament to take. The Supreme Court has made clear that Article 50 TEU can only be triggered by way of an Act of Parliament, although it did not prescribe what form that Act must take, saying that this is entirely a matter for Parliament.

It is significant that the Supreme Court has confirmed that the devolved legislatures in Scotland, Northern Ireland and Wales do not have a veto on Brexit and that the government has no legal obligation to consult them. This could have caused material delay for the government’s plans, not least given the forthcoming Stormont elections. However, the court did emphasise that the Sewel Convention acts as a political constraint that plays an important role in the operation of the UK constitution. We can expect the devolved legislatures to assert the significance of this statement in the coming weeks.

JP: As has been widely reported, the government has been preparing for this outcome for some time and intends to present a Bill to Parliament to authorise the triggering of Article 50 TEU imminently. While making the need for legislation mandatory, the judgment does not address what should be included in such a Bill and, indeed, the majority states expressly that ‘[w]hat form such legislation should take is entirely a matter for Parliament’.

However, they also note that ‘[t]here is no equivalence between the constitutional importance of a statute, or any other document, and its length or complexity’. No doubt, the length and complexity of the Bill will be subject to significant political debate and could end up back in the courts.

What is the significance of this decision for the UK, legally, constitutionally and politically?

KA: This is the most important constitutional case since I began studying as a law student. Constitutionally, it resoundingly reaffirms the power of Parliament in Westminster. Only they, and not the government in power, have the power to remove individual rights by withdrawing from the EU. However, it sounds most likely that Parliament will approve the triggering of Article 50 TEU. This will set the automatic countdown clock ticking.

HM: More detailed analysis of the outcome from a legal perspective will no doubt follow over time as experts take a detailed look at the judgment. In the short term, the significance is that Parliament will now play a part in the triggering of Article 50 TEU, and there remains a risk of derailment if the Houses of Commons and Lords seek to make significant amendments. There are also important comments regarding the extent of the devolved legislatures’ involvement in this process which will no doubt be a further source of political debate and comment politically and legally. 

We probably have not seen the end of Brexit litigation. There are other legal proceedings in the offing, not least on the important question of whether the Article 50 notice, once given, can be revoked. No issue was expressed by the Supreme Court on this point.

CB & AE: More broadly, this ruling will be studied closely by constitutional lawyers as it addresses a number of fundamental constitutional issues that rarely fall to be considered by the courts, including the interplay between the government’s executive powers in international law and legislative sovereignty, the powers of the court to supervise the exercise of prerogative powers particularly where existing law or rights are affected, and the fundamentally political, not legal, nature of the Sewel Convention on consultation of devolved legislatures. However, the court was at pains to say that its judgment reflects well-established constitutional principles.

JP: The decision does not reflect any paradigm shift in the UK constitutional or legal arena. It is, however, highly significant for its reinforcement of fundamental principles of the UK constitution and the separation of powers. In particular, all of the judgments reiterate and elucidate two fundamental principles of the UK’s unwritten constitution:

• the executive cannot change domestic law unless authorised to do so by Parliament, and
• the prerogative power of the executive generally includes a power to enter into and to terminate treaties without recourse to Parliament

The difference between the majority and the minority view arises from a difference as to how those principles are applied to the present circumstances, and in particular, the European Communities Act 1972 and subsequent related legislation. The majority also acknowledges the importance of the related principle that legal rights should not be removed without the authorisation of Parliament. 

The approach of the court also emphasises the fundamental importance of the separation of powers. The court was at pains to emphasise that this case had nothing to do with the political wisdom of leaving the EU or the political impact of the EU referendum. It was, however, the constitutional role of the court to rule on the legality of how any change was to be implemented and to ensure that parliamentary sovereignty was respected and that the executive did not act outside of its powers.

Politically, perhaps the biggest question left open by the judgment is the ongoing relationship between Westminster and the devolved administrations. The entirety of the court rejected the arguments of the devolved administrations that their consent was required before Article 50 TEU could be triggered. This argument had been primarily based on the Sewel Convention that, although having the power to do so, Westminster does not legislate on devolved matters without the consent of the relevant devolved administration (with some additional arguments based on particular legislation). Although acknowledging the political importance of the Sewel Convention, the court did not consider it was appropriate for it to be enforced through the courts. Any ‘enforcement’ was rather a matter for politics. Whether that state of affairs is acceptable to the devolved administrations politically is an open question. 

What will happen next? 

KA: The next legal steps will focus on the Bill in Westminster. The devolved administrations may seek to make political representations, but they will not have the power to block the triggering of Article 50 TEU. People who had built businesses or lives on the assumption that the UK would continue to be a member of the EU are now likely to start making changes to their plans. The Supreme Court didn’t carry out a detailed analysis of which EU law rights are theoretically capable of replication in UK law and which are not. This question will be of the greatest practical significance for individuals and businesses in the years and months to come.

HM: Theresa May’s proposed March 2017 deadline for triggering Article 50 TEU may be in jeopardy. An Act of Parliament will take time to achieve, even though any short Bill will probably be finalised this week for a speedy introduction. The standard procedure for creating a new law will have to be followed. The process will provide another airing of the arguments for and against leaving the EU in both the House of Commons and the House of Lords. There is also likely to be further debate about how the exit negotiations should be conducted, and the form of any withdrawal agreement.

CB & AE: Ministers have been managing expectations for some time, and will no doubt be ready to react. The government will be looking to get a Bill through Parliament quickly. Precedent suggests that it will be able to do that (indeed, following the events of 9/11, the Anti-Terrorism, Crime and Security Act 2001 passed through Parliament in only 32 days). There is a real risk, however, that the government may have to make concessions on parliamentary involvement in the process along the way. Already, the SNP has said that its MPs will table amendments to the Bill, and some Labour and Liberal Democrat MPs have announced that they will vote against the Bill.

JP: The government will now have to proceed to introduce a Bill to Parliament to authorise the triggering of Article 50 TEU. That Bill will be subject to debate and potential amendment in both the House of Commons and the House of Lords. Article 50 TEU cannot be triggered until the Bill is approved by both Houses and it receives Royal Assent. If the Bill includes any conditions on the triggering of Article 50 TEU, they will, of course, need to be met. The Bill may also specify conditions on how the negotiations with the EU are to be conducted and Parliament’s role in those negotiations. 

Outside Parliament, there will no doubt continue to be significant debate regarding the negotiations and the process for leaving the EU, as well as other legal challenges (some of which are already ongoing) on related matters. We will also need to wait to see the impact on relations between Westminster, the devolved administrations and the populations they represent.

Interviewed by Jenny Rayner.

This article was first published by LexisNexis.