The politically febrile aftermath of Miller I  and Miller II  is not an ideal time to consider the reform of our Supreme Court. Those decisions seemed, at the time, of enormous political significance, and partisans for the losing side (I am not one) may appear to be motivated by a desire for revenge.
There are two bad arguments for the reform of our ultimate level of appeal that I disassociate myself from at the outset.
First the claim that the change of venue and title from the Judicial Committee of the House of Lords to the Supreme Court made a substantive difference. The only thing to be regretted about this rebranding exercise is that Middlesex Guildhall, however much its interior has been altered, is a squat unattractive municipal building that is the least impressive ultimate appellate court building of any major nation (and of most minor ones).
Second is the claim that there has been an increase in inappropriate judicial activism. That does not mean that we should not guard against it, but the world of political, legally indefensible, decisions, such as that of the House of Lords in 1901 in Quinn v Leathem, driven by the Conservative Lord Chancellor the Earl of Halsbury, is not the one we now live in.
For what it is worth, I found the dissent of Lord Reed in Miller I wholly persuasive and see no answer to it in the majority or the voluminous subsequent literature, but also thought Miller II obviously right. However, neither showed that the court was in any way dysfunctional. It isn’t. That a legal dispute has political consequences does not mean that the reasons of the judges in making it are themselves political.
That said, here are seven supplemental reasons why Professor Derrick Wyatt QC’s proposal to replace the membership of our ultimate court of twelve with a rotating panel drawn from an expanded membership (of fifty?) from the Court of Appeal and elsewhere has merit.
The time when it was acceptable to have twelve white men serving as our ultimate arbiters of law has passed. It is, at a minimum, symbolically important that our judges reflect us.
If you make one appointment to a group of twelve, every three years or so, instead of four appointments to a group of fifty, diversity in appointments is much harder to achieve. The former may result in a group of all white men, the latter will not. We can achieve the twin goals of diversity and having all of our most able judges serving by changing the composition.
2. Under and Over Representation
Scotland and Northern Ireland are currently simultaneously under and over-represented on the Supreme Court.
They are under-represented because if there is an appeal on, say, an aspect of Scottish common law, the two Scottish judges will be outnumbered by three from elsewhere. Although only very rarely are the Scottish judges left in a minority on their own law, the more significant problem is that the other members of the court will defer to those from other nations on the correct view of the law of those jurisdictions. Instead of an appeal to a five member court, de facto it is to two or even one. This problem has been masked because for twenty-five years the Scottish judges appointed to our ultimate court have been of the very highest quality. This has not, however, always been the case.
They are over-represented because the proportion of judges on the court from jurisdictions other than England and Wales is larger than the size of those jurisdictions warrants. Using size of population as a rough guide, Scotland should have roughly one in twelve, when it has one in six, Northern Ireland one in thirty three.
Ring-fencing court places in this way also exacerbates the diversity problem above. All the Scottish and Northern Irish appointments have been white men.
This does not mean that having representatives from different jurisdictions sit on appeals has been anything other than beneficial to all the constituent parts of the United Kingdom. However, panels drawing more heavily on the expertise of Scotland and Northern Ireland as and when necessary, is achievable under Wyatt’s proposal. This is more substantive than the Court touring hearings around different parts of the country.
3. Lack of Specialist Knowledge
It is very important that lawyers in general, and judges in particular, do not develop a stove-pipe mentality, believing that only public lawyers can understand administrative law, or only company lawyers directors’ duties. Having judges with a range of expertise drawn from different areas is helpful in avoiding the errors caused by group think.
That said, a panel of twelve will not cover the full range of practice that will be litigated before the court. The court is therefore in some cases reliant upon counsel to ensure that its members understand the issue fully which is usually, but not always, the case.
The area where this has caused most difficulty is the criminal law. The history of notorious decisions in the criminal law is a long one. The lack of criminal law expertise has been alleviated to an extent by co-opting the Lord Chief Justice on to the court. But we can do better. Wyatt’s proposals would allow the composition of the court to include more members with practical expertise in an area. Overtime, this should improve the quality of our law.
4. Equitable Work Loads
Although I agree with the late Peter Cook as to how tough the job of a judge is, it is the case that that Supreme Court judges have more time to decide individual cases than is afforded members of the Court of Appeal. This is appropriate, we want the final appellate court to have more time in reaching its decisions. If we aggregated the membership of the Court of Appeal and Supreme Court, we could distribute the workload more equitably (ie we could give members of the Court of Appeal a break from the grind).
5. Protection from Political Interference
It is much to the credit of our Supreme Court that the press and public generally do not care who they, as individuals, are (as opposed to legitimate concerns about the overall composition of the court). Inevitably, when cases of political importance are decided, there is an uptick in interest. The enormous political significance of appointments to the United States Supreme Court creates great press coverage, and inevitably bleeds into a belief that the identity and political views of our judges matters here.
We can protect our judges, who in my experience have generally no interest in having celebrity status, by anonymising them in a larger group. The pressure to have some kind of political “oversight” in their appointment will also be removed. Little point, when the group is 50 and not 12.
6. Courts within the Court
Because the UK Supreme Court does not generally sit en banc, the problem that has arisen elsewhere (most obviously in the United States Supreme Court, but also recently in the High Court of Australia) of judges operating in cohesive groups, and so as a majority court within the court, has not usually arisen. However, although lack of self confidence is not much of a problem in our senior judiciary, it is the case that able and dominant personalities can achieve a degree of influence over their colleagues when working together as a group overtime. A rotating panel would prevent these problems from arising.
7. Continuity of Role
The job of a member of our ultimate appellate court is to decide the case before her according to the positive law and principles of justice. This is exactly the same job as that of a member of the High Court or Court of Appeal. The only difference is the extent to which previous decisions bind its members. There is no drop off in quality between the members of our ultimate appellate court and that of the Court of Appeal, indeed the court of Scrutton, Bankes and Warrington LJJ was more than a match for that of any five of the members of the House of Lords in that era.
Members of the Supreme Court are not junior members of the legislature, enacting delegated legislation. The occasions when members of the court have lost sight of this are vanishingly few, but a change in composition should prevent it altogether.
Two arguments against Wyatt’s proposals have been made. 
First is the logistical one of determining who serves when on our ultimate court. This seems trivial. We need a basic rotation rule, modified by expertise and availability. A more complex, but hardly Byzantine, version of precisely the system currently in operation.
Second is the suggestion that members of the Court of Appeal may be reluctant when serving on the ultimate court to overturn their colleagues.
This suggests a degree of timidity that is not my experience of senior members of the judiciary.
Robert Stevens is Herbert Smith Freehills Professor of English Private Law, University of Oxford
 R (Miller) v Secretary of State for Exiting the European Union  UKSC 5.
 R (Miller) v The Prime Minister  UKSC 41. Cherry I in Scotland.
  AC 495.
 But see Cleisham v British Transport Commission 1964 SC (HL) 8 (Lords Reid and Guest dissenting) AG Ref No 2 of 2001  2 AC 72 (Lords Hope and Rodger dissenting).
 But not the only one. AIB Group (UK) v Mark Redler  UKSC 58 would have greatly benefitted from having had a judge familiar with accounting principles in equity, and why the common law analogues the court relied upon were the wrong ones.
 Eg DPP v Smith  AC 290 (which caused the High Court of Australia to decide that decisions of the House of Lords were no longer binding Parker v R (1962-63) 111 C.L.R. 610); Shaw v DPP  AC 220 (the invention of a crime); Anderton v Ryan  AC 560 (so obviously wrong it was reversed a year later, R v Shivpuri  AC 1); R v Hinks  3 WLR 1590 (the sorry history of the interpretation of “appropriation” in the law of theft here reached its zenith); Ivey v Genting Casinos  UKSC 67 (regardless of the merits of the decision, we should not be greatly expanding the scope of criminal culpability in obiter dicta in contract cases).
 Peter Cook “Why I’d Rather Be a Judge than a Coal Miner” https://www.youtube.com/watch?v=ed0UgcXZCh8&ab_channel=crokit
 The description of Sir Terence Etherton MR by the Daily Mail as an “openly gay ex-Olympic fencer” was a laughable low-point https://www.dailymail.co.uk/news/article-3903436/Enemies-people-Fury-touch-judges-defied-17-4m-Brexit-voters-trigger-constitutional-crisis.html
 Unfortunately, I agree with Lord Mance (in dissent) in Patel v Mirza  UKSC 42 - that the attempt to re-write the applicable rules on illegality to a much wider range of cases than arose in that case to be decided was wholly inappropriate. The court itself has begun to retreat from the error of that decision Stoffel 7 Co vv Grondona  UKSC 42, .