The Supreme Court's hearing on prorogation

As a public law case where multiple senior judges have disagreed, the prorogation cases will be heard by a large panel

Chris Hanretty
Sep 11, 2019 · 3 min read
Institution of the Court of Session by James V in 1532, detail from the Great Window in Parliament House, Edinburgh. By Kim Traynor — Own work, CC BY-SA 3.0,

Earlier this morning (Wednesday 11th September), the Inner House of the Court of Session ruled that the prorogation of Parliament, which took place on Tuesday morning, was unlawful. All three judges agreed.

The decision follows a previous ruling by a Division Court of the High Court of England and Wales, composed of the Lord Chief Justice, the Master of the Rolls, and the President of the Queen's Bench division.

The unexpected decision from the Court of Session now presents the Supreme Court with an almighty headache. Senior judges in two different jurisdictions have now disagreed on the correct interpretation of UK law.

The first decision that the Supreme Court (or more accurately, the President and Deputy President of the Court) will have to make concerns the size and composition of the panel which will hear the case.

In a forthcoming book on judicial behaviour on the Supreme Court (A court of specialists: judicial behaviour on the UK Supreme Court, OUP, out sometime in the space year 2020), I look at both panel size and composition. For panel size, I find that:

  • panels are larger in "more important" cases, where more important means "more important legally", and where this is measured by looking at the number of generalist law reports (WLR, All ER, SJLB, Times; Session Cases, Scots Law Times and Green's in Scotland) which have reported the case.
  • panels are larger in cases where the government is involved;
  • panels are larger where there is greater "disagreement below", or where the ratio of (a) the number of judges who have ruled for the appellants to (b) the number of judges who have heard the case is higher.

For panel composition, I find that:

  • specialism in the relevant area of law (public/family/civil/tax and chancery/Scots/NI) is the single most important predictor of who will sit, and is more important the more important the case;
  • seniority matters, but only in more important cases (otherwise more senior judges would always be hearing a disproportionate caseload)
  • judges who agree with the presiding judge are actually less likely to be chosen in more important cases: far from stacking the bench, judges try to broaden it.

What does this imply for the hearing on Tuesday?

In terms of panel size, this is a case of the highest importance which involves the government, and where the judges that have heard the case are split 3:4 (three judges from CSIH versus the three judges in the High Court and one judge in the Outer House of the Court of Session). Because these cases are so recent, I can't create the same measure of importance I use in the book, but I would be surprised if the decisions were not reported in all of the reports I have just mentioned.

It's therefore difficult to see the Supreme Court sitting in a panel smaller than nine. It's not clear to me whether the Supreme Court would sit in a panel of eleven, which it did for the Miller case. It suited the internal politics of the court to sit in eleven for Miller, because the court was one member short. The court cannot sit as twelve (it must have an odd number of judges), and so if the court were to sit in a panel of eleven, it would necessarily leave out one judge. That might make a panel of eleven an unappealling choice. On the other hand, the division of opinion in Cherry/Miller no. 2 is greater and more concentrated than any divisions in Miller no. 1 — though obviously we still need to see the full text of the reasons of the High Court and Court of Session.

Panel composition is obviously a lot easier when the panel is made up of eleven judges, because the choice becomes a choice about which single judge to leave out. Seniority would suggest leaving out the most junior judge, but since Lord Sales (who became a Justice of the Court in January 2019) has more experience in public law than Lord Kitchin(October 2018), it may be that Lord Kitchin is left out. If the panel was a panel of nine, then a logic of specialisation would suggest that Kitchin, Briggs and Arden might not make the cut.

Chris Hanretty

Written by

Professor of Politics, Royal Holloway

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