Dean Knight: Reasoning Through Challenges to Prorogation: Cherry and Miller (No 2)

The challenges to the prime minister’s request to the Queen to prorogue Parliament in the face of the fast approaching Brexit deadline have many fascinating dimensions (Cherry v Advocate General [2019] CSIH 49 and R (Miller) v Prime Minister [2019] EWHC 2381 (Miller (No 2)). The question of justiciability has been at the forefront. And remedy — especially the consequential effect of the Cherry ruling — also looms large. But the dimension I find especially curious is a doctrinal one, about the appropriate ground of review or methodology employed to scrutinise the decision to prorogue. The Inner House of the Court of Session seized on improper purpose as the key trigger for intervention. Proroguing at this time would ‘stymie’ essential parliamentary scrutiny of the government’s tactics and actions in relation to Brexit.

In this post, I reflect on the grounds used by the court in Cherry to justify intervention and float some other ways the courts might reason through whether the prime minister’s request justifies judicial intervention. One way of thinking about judicial supervision — and debates about whether a basis for intervention has been made out — is a struggle between vigilance on the one hand and restraint on the other (see Knight, Vigilance and Restraint in the Common Law of Judicial Review (CUP, 2018)). Here, arguments that the power to prorogue must be exercised properly and democratically have strong normative force. But so too do arguments in favour of being circumspect, respecting the political and judges not weighing in on things they are not adept at judging. This novel context reveals this contest perhaps more than in workaday judicial review cases. How, then, might the courts reason through that delicate balancing process in the prorogation case?

The tradition in England and Wales — and, I am assured as I am not expert in the jurisdiction, Scotland too — is to reason through a grounds of review framework. Grounds express a natural balance: legality is vigilant; unreasonableness restrained. Variability in depth of scrutiny comes indirectly, either by framing a complaint under different grounds or by circumscribing the available grounds by a doctrine of non-justiciability.

We see the latter in Miller (No 2). We don’t reach the grounds of review because the circumstances (high policy and absence of legal benchmarks) demand absolute restraint: a blanket no go zone. Yet complete categorical restraint like this seems out of step with the direction of travel of modern judicial review.

Cherry generally follows a traditional grounds of review framework but reaches a different conclusion than in Miller (No 2).

First, Lord Carloway didn’t think the orthodox grounds applied but said there was an actionable breach of constitutional principle. We could think about this as a relatively novel ground of review. Or, as Mark Elliott (‘Prorogation and Justiciability’) and Alison Young (‘Prorogation, Politics and the Principle of Legality’) explain, the illegality ground supercharged by the principle of legality. This principle moves matters like the wisdom and fidelity of the decision from restrained unreasonableness grounds into the vigilant legality ground, effectively enabling de novo review by the courts. While presented as benign and orthodox, the choice to vary the depth of supervisory eye demands careful justification.

Secondly, Lord Drummond Young reasoned the call for intervention in terms of the improper purpose ground. Again, an ostensibly uncontroversial ground but one that is slippery. Improper purpose (whether an aspect of the legality ground, a touchstone of the unreasonableness ground or a ground of review in its own right) can be applied benevolently, with restraint, or aggressively, with vigilance. Thus improper purpose, without more, raises suspicion about whether the courts have pressed it too hard – as might be the case here.

Thirdly, Lord Brodie echoed concern about the decision being made for an improper purpose but also wondered if the irrationality ground was also made out. In doing so, Pham’s ‘sliding scale’ of justification was accepted as being in play — adding another doctrinal method for mediating competing claims for vigilance and restraint, namely explicit calibration of intensity of review (a style of reasoning I argue has considerable virtue). Curiously, though, Lord Brodie was vague about which way the scales slid. On the one hand, he had been invited to apply more vigilant anxious scrutiny. On the other hand, he characterised the prime minister’s actions as ‘egregious’ (commending the language of Sales LJ referring to cases where there was ‘a clear failure to comply with generally accepted standards of behaviour of public authorities’), suggesting intervention was triggered even with light-handed review.

In highly charged cases like this, the desire to present judicial supervision and methodology as trite and ordinary is understandable. Yet the casual employment of grounds does little to assuage concerns otherwise.

Finally, based on the gist of the court’s concern in Cherry, some other approaches to justify intervention might be open.

The first keeps the court within a grounds of review framework but acknowledges that the circumstances demand the modification or circumscription of the grounds of review. In other words, rather than non-justiciability being absolute, a form of second non-justiciability is deployed (as Harris calls it (‘Judicial Review, Justiciability and the Prerogative of Mercy’ (2003) 62 CLJ 631)) where the traditional grounds are replaced with more restrained grounds, for example, bad faith, corruption, fraud or other variations. Recall the Court of Appeal’s approach in Cart ([2010] EWCA Civ 859) and add examples from New Zealand and Canada, especially in cases dealing with, for example, commercial decisions, self-regulatory bodies, or prosecutorial discretion where calls for restraint speak loudly. One benefit of this approach is that it avoids the unpalatable bluntness of non-justiciability, while still respecting the conceptual concerns counselling restraint. In doing so, it is open to a finding that the request to prorogue met this higher threshold of flagrant impropriety, without needing to shoehorn the complaint into traditional grounds in unfamiliar circumstances. In some respects, this could be an explanation of Lord Brodie’s sliding scale approach but expressed in familiar grounds of review rather than calibration of intensity.

A second, as Ewan McGaughey (‘Is There a “Legal Measure” to Judge Parliament’s Prorogation?’) suggests, is the proportionality ground. However, it would be a bold move to (finally) canonise that as a free-standing common law ground of review in this context. And, while proportionality provides structure, it doesn’t itself resolve crucial questions of depth of scrutiny.

A third approach — although one I’m not a fan of — comes from the Court of Appeal’s decision in Guinness ([1990] 1 QB 146), where Lord Donaldson spoke of the courts intervening when ‘something had gone wrong of a nature and degree which required the intervention of the court’. This is sometimes called the innominate ground, although I prefer to think of it as a distinct style of contextual review involving judicial appraisal in the round without any doctrinal guidance (see ‘Contextual review: the instinctive impulse and unstructured normativism in judicial review’). There are obvious rule of law concerns about this trigger for intervention. But this (and kindred formulations) pop up throughout the Anglo-Commonwealth now and then — especially when the institutional context lacks traditional legal benchmarks for evaluating a decision under review.

The contest between demands for vigilance and restraint in Cherry and Miller (No 2) is especially acute. Others here and elsewhere have offered useful views on that tension and the strength of those claims. Doctrinal methodology provides a means by which judges can reason through those competing claims, each of which has different virtues when measured against the rule of law. The speedy circumstances may mean it is overly optimistic to expect too much from the Supreme Court on judicial review’s schematic architecture and different styles of reasoning but we should expect some care about the doctrinal device used to balance the competing claims for vigilance and restraint.

The author thanks, subject to the usual caveat, Eddie Clark, Martin Loughlin, Tom Poole and Paul Scott for comments on a draft of this post.

Dr Dean R. Knight, Associate Professor, Faculty of Law, Victoria University of Wellington; Visiting Fellow, London School of Economics and Political Science and Bingham Centre for the Rule of Law.

(Suggested citation: D. Knight, ‘Reasoning Through Challenges to Prorogation: Cherry and Miller (No 2)‘, U.K. Const. L. Blog (16th Sept. 2019) (available at