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Aileen McHarg: Article 50, Parliamentary Authorisation and the Sewel Convention

The Divisional Court’s ruling in R (Miller) v Secretary of State for Exiting the European Union that parliamentary authorisation is required before the Prime Minister can give notice of the UK’s intention to withdraw from the EU under Article 50(2) TEU raises the question of what role, if any, the devolved legislatures will have in that process. 

The Divisional Court in Miller did not consider it necessary to address this issueHowever, it was central to the earlier decision of the Northern Irish High Court in McCordMcCord, in contrast to Miller, concluded that prior parliamentary authorisation was not required to trigger Article 50.  But even if it was, the court took the view that such legislation would not engage the Sewel Convention at least as it applies in Northern Ireland because it would relate to “excepted matters” under the Northern Ireland Act 1998 (NIA) (i.e., matters outwith the scope of devolved competence).  

Nevertheless, there is an argument to be made that, if the Supreme Court upholds the Divisional Court’s reasoning in Miller, the Sewel Convention would be engaged, at least as far as Scotland is concerned.

The Divisional Court’s Reasoning in Miller and its Application to the Scotland Act 1998

The central issue in Miller was whether, as the UK Government contended, notification of the UK’s intention to withdraw from the EU was a matter for it alone acting under the royal prerogative power to conduct foreign affairs, or, as the applicants contended, the prerogative had been ousted by the European Communities Act 1972 (ECA).  The ECA was enacted to give domestic effect to the accession treaty by which the UK became a member of what was then the EEC.  Although the ECA makes no express reference to Article 50, and is silent on the question of whether the foreign affairs prerogative has been curtailed in relation to EU matters, the Divisional Court – in an expansive (and contestable)[1] reading of the ECA – held that the prerogative had been ousted by necessary implication. 

There were essentially two parts to the court’s reasoning.  First, it argued that rights derived from EU law had their domestic source in the ECA, and the government could not therefore rely on the prerogative to remove or vary those rights.  It is a clearly accepted constitutional principle that prerogative powers are subordinate to statute; and the court assumed that triggering Article 50 would lead inexorably to the removal of EU-derived rights.  Secondly, the court argued that various provisions of the ECA assumed continued membership of the EU: section 2(2), which empowers ministers to implement EU obligations by Order in Council, and section 3(1), which refers to the ability to make preliminary references for rulings on the meaning of EU law to the Court of Justice of the EU (CJEU) (see para 93 (5) and (7)).  Again, therefore, to rely on the prerogative to withdraw from the EU would be to thwart the intention of Parliament. 

The first part of the court’s reasoning has no application to the Scotland Act 1998 (SA) or the other devolution statutes: they cannot plausibly be regarded as a source of EU-derived rights.  However, the SA clearly does presume the UK’s continued membership of the EU, and it has always been accepted that, in order to complete the UK’s withdrawal from the EU, the SA, like the ECA, would need to be amended.  Thus, there are direct equivalents of sections 2(2) and 3(1) ECA in the SA: section 53, read with section 57(1) empowers the Scottish Ministers to implement EU obligations; and section 34 provides for the making of preliminary references to the CJEU in circumstances where the legislative competence of a Holyrood Bill has been referred to the Supreme Court under section 33.  And of course, sections 29(2)(d) and 57(2) prohibit the Scottish Parliament and Scottish Government respectively from acting in breach of EU law.

Clearly, the SA would be less centrally affected by withdrawal from the EU than the ECA.  The EU law provisions are only one part of the devolution scheme, rather than its very raison d’être.  And the obligation to comply with EU law in the SA would still be legally effective (even if practically strange) in a way that the instruction in section 2(1) ECA to give domestic effect to “[a]ll such rights, powers, liabilities, obligations and restrictions from time to time created or arising by or under the Treaties …” would not.  This might be regarded as sufficient to distinguish the two statutes.  Nevertheless, EU withdrawal would have significant direct and indirect effects on the scheme of devolution established by the SA.  It is, therefore, at least arguable that, were the UK Government to proceed with notification of withdrawal under the royal prerogative, this would thwart Parliament’s intention when it enacted the SA, just as it would thwart its intention as embodied in the ECA.

Assuming this is accepted, why would it matter?

The Divisional Court argued that the ECA, as a “constitutional statute” cannot be impliedly repealed, but must be expressly repealed.  It seems to follow (a) that the “parliamentary authorisation” required to trigger Article 50 must take the form of legislation, rather than, say, a House of Commons resolution (something confirmed by David Davis MP in his statement to Parliament on 7 November) and (b) that such legislation would have to make express reference to its implications for the ECA.

Since the SA has similarly been held to be a constitutional statute (H v Lord Advocate), it also seems to follow that the SA would equally require to be expressly repealed.  This, then, raises the question whether any such express repeal of the SA would require the consent of the Scottish Parliament under the Sewel Convention.

The Scope of the Sewel Convention

The dispute in McCord did not concern whether, if legislation were required to trigger Article 50, this would materially affect the NIA, but rather the scope (and enforceability) of the Sewel Convention.  The court took a narrow view of the scope of the Convention, holding that it was limited to situations in which the UK Parliament is legislating on matters devolved to the Northern Ireland Assembly (such as health or education).  The court acknowledged a broader view, supported by a note submitted to the Attorney General for Northern Ireland by the Lord Advocate, whereby the Convention is engaged in relation to legislation affecting the scope of devolved competence.  But the court found nothing in the history of the Convention as it applied to Northern Ireland, either since 1999 or under the earlier period of devolution, to support the broader interpretation.  In any case, as a matter of convention, not law, the court considered that any requirement of devolved legislative consent was not legally enforceable.

In view of the Lord Advocate’s position, the court accepted that the situation might be different in Scotland.  It is certainly arguable that it is.  Devolution Guidance Note 10 envisages that the Scottish Parliament’s consent should be sought for any adjustment to the scope of devolution, and consent was in fact sought for both the Scotland Act 2012 and the Scotland Act 2016.  Unlike in Northern Ireland, the Sewel Convention was also placed on a “statutory footing” for Scotland by section 2 of the Scotland Act 2016.

However, the issue is not clear cut.  One problem is section 2 of the 2016 Act itself.  There was a good deal of argument at the time of its enactment as to whether the statutory wording captured only the narrow view of the convention as applied in McCord, or the broader view as practised in Scotland.  The UK Government sought to distinguish the Convention strictly so called (the narrow view, as declared by Lord Sewel during the passage of the SA) from the (broader) practice of legislative consent in Scotland.  This was unconvincing from analytical perspective, but it might persuade a court that the words contained in section 2 were not intended to bear the broader meaning.  In any case, and more convincingly, the UK Government argued that section 2 did not place any legally enforceable restriction on the ability of the UK Parliament to legislate for Scotland (i.e., the Convention remained a convention).  In addition, as the House of Lords Constitution Committee pointed out in its report on The Invoking of Article 50, the Sewel Convention only requires devolved consent “normally”.  In the Committee’s view, it was arguable that the Convention would not apply to legislation relating to withdrawal from the EU, since these circumstances are not normal within the meaning of the Convention.  Moreover, a Bill authorising withdrawal could potentially be sufficiently narrowly drawn (i.e., leaving sections 29 and 57(2) SA in place) such that it does not affect (or does not significantly affect) the scope of devolved competence.


Assuming that the Supreme Court will hear the appeals in Miller and McCord together, and given that the Lord Advocate is likely to intervene in the proceedings on behalf of the Scottish Government, the Supreme Court will be unable to side-step the devolution implications of a decision that the UK Government must seek parliamentary authorisation to trigger Article 50 in the way that the Divisional Court did.  Even if the Supreme Court holds that the Convention is not legally enforceable, its ruling as to the scope of the Convention will (should?) be highly authoritative and effectively decisive. 

It is by no means certain that the Supreme Court will hold either that parliamentary authorisation is required or, if so, that this will engage the Sewel Convention.  However, if it does so hold, what would be the implications?

First, it seems unlikely that the Scottish Government would wish to veto legislation authorising withdrawal altogether.  It has been careful since the EU referendum to argue that the will of the Scottish people to remain in the EU should be respected, not that this should override the desire of the majority in England and Wales to leave.  Instead, a requirement of devolved consent would appear, on the face of it, to give the Scottish Government significant additional leverage to argue for protection of Scotland’s position, via a grant of conditional consent (as Holyrood did in relation to the Scotland Act 2012).  Indeed, it seems probable that MPs and peers in general will use the parliamentary process to attempt to flush out, and influence, the UK Government’s negotiating position, rather than to seek to block Brexit altogether. 

While the Miller decision is therefore unlikely ultimately to “reverse” the referendum result, it is nevertheless likely to delay the triggering of Article 50, pending further parliamentary scrutiny, and negotiations between the UK and devolved governments.  In the current febrile political atmosphere, however, even delay is likely to be unacceptable to Brexiteers, and the UK Government may come under significant political pressure simply to ignore any reservations expressed by Holyrood or the other devolved legislatures.  It goes without saying that overriding a legislative consent motion would significantly exacerbate tensions between the UK and Scottish Governments.  Indeed, forcing an open confrontation is not something that either Government is likely to want. 

In short, there is a risk, if the decision in Miller is upheld, that it will make the constitutional mess created by the EU referendum result harder rather than easier to resolve.  The Divisional Court’s decision was based on constitutional principle, but it took a very restricted view of the relevant constitutional landscape, focusing narrowly on the relationship between Crown and Parliament.  While for centuries this relationship could have been said to be the central constitutional dynamic in the UK, in the contemporary constitutional order it produces an approach to the (legal) resolution of the current crisis which ignores other significant constitutional actors: the people of the UK via the referendum and the peoples of the UK via the devolved legislatures.  It is to be hoped that the Supreme Court will show greater sensitivity to the full constitutional implications of the case.

Aileen McHarg is Professor of Public Law at the University of Strathclyde

I am grateful to Mark Elliott, Chris McCorkindale and Tom Mullen for helpful discussions on the issues covered by this post.  The usual disclaimers apply.

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