Alan Greene: Miller 2, Non-justiciability and the Danger of Legal Black Holes

In R (Miller) and Others v The Prime Minister (hereinafter Miller No.2), the High Court of England and Wales found that the decision of the Prime Minister to advise the Queen to prorogue parliament was non-justiciable. In doing so, the judgment reveals the propensity of the judiciary to be much more protective of its own empire than that of the legislature. Ultimately, however, it is an approach that undermines both due to the creation of a legal black hole.

Legal holes and Miller No.2

Legal black holes are zones formally created by law within which, no recourse to the law can be made. A legal black hole is thus created when there is no legal control on the body exercising the power in question, leaving the decision-maker free to exercise their absolute discretion. At best, all the judiciary can ask is whether the legal black hole was validly created. There is therefore a close link between legal black holes and non-justiciable or political questions. Legal black holes should be distinguished from what David Dyzenhaus refers to as legal grey holes—questions of law which courts state that they do have the capacity to review; however, the review exercised is so light touch that it is essentially meaningless. Dyzenhaus contends that legal grey holes are more dangerous than legal black holes as the former cloak the decision with a thin veil of legality, thus legitimising them in a way that a finding of non-justiciability does not.

In Miller No. 2 the approach of the Court is to essentially create a legal black hole regarding the exercise of the prerogative power to prorogue Parliament. The Court found (at [51]) that:

The Prime Minister’s decision that Parliament should be prorogued at the time and for the duration chosen and the advice given to Her Majesty to do so in the present case were political. They were inherently political in nature and there are no legal standards against which to judge their legitimacy.

Ostensibly, this appears to be an exercise in judicial restraint albeit one that creates a legal black hole. What Miller No. 2 shows, however, is how a finding of non-justiciability can, nevertheless, legitimise a decision. Even such a thin conception of the rule of law such as that deployed to create a legal black hole can add a degree of legitimacy to a decision. This thin veil of legitimacy, however, is further compounded when the court accompanies its finding of non-justiciability with an implicit endorsement of the reasons given by the decision-maker. This is essentially what the Court does in Miller No. 2 (at [51]):

The evidence shows that a number of considerations were taken into account. We have summarised them extensively already. They included the need to prepare the Government’s legislative programme for the Queen’s Speech, that Parliament would still have sufficient time before 31 October 2019 to debate Brexit and to scrutinise the Government’s conduct of the European Union withdrawal negotiations, that a number of days falling within the period of prorogation would ordinarily be recess for party conferences, and that the current parliamentary session had been longer than for the previous 40 years…

Miller No. 2 is thus an example of the negative effects of a legal black hole and a legal grey hole. If the risks of a legal black hole are to be mitigated, their inherent illegitimacy must be acknowledged. Courts must therefore refuse to look at the decision-maker’s reasoning out of risk of endorsing this reasoning— explicitly or otherwise. For this reason, the courts were correct (at [41]) to reject Lord Pannick’s submission that the court should:

…explore the facts first, for the purpose of deciding whether there has been a public law error, and then turn to justiciability; and then in the limited sense of deciding whether “caution” should forestall intervention.

Lord Pannick’s suggestion would have the benefit of gaining some sort of judicial disapproval in a case which was ultimately lost on the justiciability question; however, the opposite occurs in the instant case where no error has been identified.

The consequences of legal black holes

It may be that the Court implicitly acknowledged the Government’s case regarding the purpose of prorogation in order to reassure itself of the ramifications of its judgment. This too can be seen by the Court (at [66]) downplaying hypothetical arguments pertaining to the consequences of a finding of non-justiciability:

We do not believe that it is helpful to consider the arguments by reference to extreme hypothetical examples, not least because it is impossible to predict how the flexible constitutional arrangements of the United Kingdom and Parliament itself, would react in such circumstances.

The difficulty with this argument, however, is that the doctrine of non-justiciability necessitates extreme hypotheticals due to its ‘all or nothing’ quality. If a five week prorogation is non-justiciable, then so too is a five month prorogation or longer. The question is non-justiciable in all instances, not just on the facts presented before the court. Indeed, it is these very extreme hypotheticals that assist in distinguishing a legal black hole from the even more sinister zone beyond law, the latter of which resemble Carl Schmitt’s contention that sovereign power exists prior to the legal order and thus cannot be constrained by law. While most legal black holes do not give rise to this risk, those that have the potential to usurp fundamental constitutional norms do.

At the time of writing, the Scottish Court of Session’s judgment in Cherry on this same issue was not available; however, the court summary does suggest that it took this question of the constitutional ramifications of prorogation much more seriously:

The Lord President, Lord Carloway, decided that although advice to HM the Queen on the exercise of the royal prerogative of prorogating Parliament was not reviewable on the normal grounds of judicial review, it would nevertheless be unlawful if its purpose was to stymie parliamentary scrutiny of the executive, which was a central pillar of the good governance principle enshrined in the constitution; this followed from the principles of democracy and the rule of law.

In contrast, the Court in Miller No.2 took a narrow reading of the principle of parliamentary sovereignty, rejecting (at [63]) ‘Lord Pannick’s formulation of a wider legally enforceable concept of Parliamentary Sovereignty, distilled to its essence as an ability to conduct its business unimpeded’ on the basis that it runs into ‘difficulties in identifying measures against which allegedly offending action may be judged.’ Equally, however, similar criticisms could be levied at the concept of the rule of law developed and applied in seminal cases such as Anisminic, Evans, and more recently, Privacy International.


It would appear therefore that while courts have jealously guarded their own jurisdiction, should the Supreme Court follow the judgment of the High Court, they would not have afforded Parliament the same courtesy they afford themselves. Thus while a finding of non-justiciability may ostensibly appear the court to be exercising judicial restraint, it is done so in a highly problematic manner, opening up the aforementioned judgments to further accusations of judicial activism.

Ultimately, when there is a clash between the legislature and the executive, it is inevitable that the judiciary gets asked to adjudicate. I would contend that abandonment of non-justiciability in favour of a spectrum of deference is a more nuanced and flexible approach. Such an approach would avoid the aforementioned risks of a legal black hole and take proper account of high political issues that courts may not be suitable for a court to second-guess. It remains to be seen what approach the Supreme Court takes.

Alan Greene is a Senior Lecturer in public law and human rights at Birmingham Law School.

(Suggested citation: A. Greene, ‘Miller 2, Non-justiciability and the Danger of Legal Black Holes’, U.K. Const. L. Blog (13th Sept. 2019) (available at