The prorogation case: a matter of principle – Part 2 of 2

This post was contributed by Colin Munro, Emeritus Professor of Constitutional Law, University of Edinburgh and tutor for Undergraduate Laws.

A few days ago I published a blog which detailed the Supreme Court’s judgement surrounding the decision to prorogate Parliament. I posed a number of questions there and I hope that these have provoked some discussions for you. This post has some comments on those questions.

Question mark banner.

Was this case about Brexit?

It was about one of the twists or turns on that tortuous road.  The Johnson government, in its determination to honour the referendum result, had been tempted to take a short cut that might reduce impediments.  However, the case did not directly concern the destination.

The justices, no doubt preferring not to be slated as “enemies of the people” or such like in the toxic atmosphere of contemporary politics, were keen to emphasise that the issue was not about the UK’s departure from the EU [1].  They also observed that, while the referendum result had not technically been legally binding, it has since been treated as politically and democratically binding” [7].

Was this case about constitutional conventions?

No.  The High Court not only found no legal restrictions on the length of prorogation, but observed too that “there is not even a constitutional convention which governs the matter”, before hastening to add that conventions are not enforceable by courts anyway [54].  The Supreme Court was careful to maintain that it was identifying legal limits on the exercise of power.

Did the case involve parliamentary sovereignty?

The case did not concern what may or may not be done by Act of Parliament or the validity of a purported Act.  However, in reaching its decision the Supreme Court used an expanded concept of parliamentary sovereignty that included protection for Parliament’s ability to enact legislation.  In the court’s recognition and defence of   this wider conception of parliamentary sovereignty, there is some analogy with Fire Brigades Union [1995] 2 WLR 1 and with Miller [2017] UKSC 5.

Did the case involve the rule of law?

Perhaps curiously, the phrase “the rule of law” does not appear anywhere in the Supreme Court’s judgment.  However, the subjection of even the most powerful in the land to legal rules is central to many rule of law theories.  For example, for Lord Bingham in his book on the subject, one of the eight key characteristics of a system conforming to the rule of law is that “Ministers and public officers at all levels must exercise the powers conferred on them in good faith, fairly, for the purpose for which the powers were conferred, without exceeding the limits of such powers and not unreasonably” (The Rule of Law, p 37).  The tenor and even the terminology of the Supreme Court’s ruling accorded closely with this demand, and it is entirely foreseeable that the case will come to be cited along with others such as M v Home Office [1994] 1 AC 377 in discussions of the concept.

Did the separation of powers feature?

The doctrine of the separation of powers was mentioned several times by the courts involved in this case, and it can be argued to have been very relevant.  The Supreme Court used the “fundamental principle” of parliamentary accountability as a standard leading to its decision, and parliamentary accountability may be viewed as one of the “checks and balances” which one version of the separation of powers theory demands.

However, it is important to realise that there are different versions of what the separation of powers entails when one drills down into the literature and discussions.  These different versions have different and sometimes inconsistent implications, as displayed in Fire Brigades Union [1995] 2 WLR 1, where the 3-2 split amongst the judges reflected different understandings of the theory.  The decision in Miller/Cherry can be seen as the judicial branch stepping up to protect the legislative branch against a threat from the executive.  However, on another view of the separation of powers, judicial restraint would have been appropriate so as not to trespass on another institution’s functions.

Do we learn anything about the royal prerogative from this case?

The principles of the law concerning the prerogative were essentially confirmed and applied. The case does, however, provide further demonstration that the obiter dicta regarding non-justiciability found in Council of Civil Service Unions [1985] AC 374 need to be treated with some scepticism.  The exclusion of some prerogative powers from justiciability in the abstract, as Lord Roskill seemed to suggest in that case would be appropriate, can no longer be taken to represent the law.  It is rather the specific exercise of a power in a particular instance that has to be decided to be justiciable or not.

Where does the case leave the prerogative of prorogation?

There is still a prerogative power to prorogue Parliament, but the common law imposes some limits on its use, if it is to be exercised lawfully.  A prorogation for six or seven days with the purpose of preparing for a new session of Parliament and a Queen’s Speech would be unexceptionable.

Like other prerogatives, prorogation is always liable to be regulated or constrained or abolished by Act of Parliament.  The related prerogative of dissolution was abolished and replaced by statutory provisions in the Fixed-term Parliaments Act 2011, at which time the power of prorogation was explicitly left untouched (s.6).

Should the case have been dismissed by reason of parliamentary privilege?

Some commentators and lawyers had suggested that Article 9 of the Bill of Rights (1688), which bars courts from questioning “proceedings in Parliament”, should have prevented the court from acting in this area.  However, a narrow interpretation of the phrase, confining it to business or actions of the Houses in a collective capacity, has prevailed in recent times, as in R v Chaytor [2010] UKSC 52 (a case concerning prosecutions over false expenses claims), and the Supreme Court readily rejected the suggestion.  The act of prorogation, it observed, was not done by the Houses, but was done to the Houses, bringing their business to an end [68].

Was this a landmark case?

It might rather be called an important case.  There was predictably much sound and fury surrounding it in these turbulent times.  Politically, the case may have been important for the yellow card shown to a Prime Minister who was showing signs of being prepared to bend the rules. Legally the effects are more doubtful.  The Supreme Court called the case a “one off” [1]. In a rather open case, where the result was not obviously determined by rules or precedents, the unanimity of approach was perhaps surprising, and perhaps its most interesting aspect was the resort to reasoning from a selection of claimed “constitutional principles.”


  1. Thank you for your very clear answer, Professor. It is always a pleasure to follow your reasoning.

    I am still not clear whether in fact this case is one which does originate from constitutional conventions. If the right to prorogue is a poltical process, albeit through prerogative residual crown powers per Dicey- , it is still in origin a convention not a legal matter, is it not? In your lectures you state that this a mistake many students make, that Royal Prerogative is common law based. That in fact:

    Royal Prerogative does not have its origins in convention but in common law. Accoring to your definition:

    ‘’comprising those attributes belonging to the Crown which are derived from common law, not Statute, and which still survive’’. The royal prerogative amounts to the residue of the Crown’s unique common law powers which were above and beyond those shared with other legal persons.

    I understand that this is the collective wisdom of the profession. Yet in the absence of anything written, given that the nature of the restoration of the monarch and sovereignty of power exercised through a Sovereign Parliament was achieved by convention, is it safe to reach to common law as the source of prerogative? Or given Parliament’s sovereignty was achieved by an acceptance – convention – of the separation of powers, that in fact the origin of the Royal Prerogative must derive from that convention, of accepting the separation of powers, Law, Legislature and Government in Parliament… The rule of law through common law legitimates Royal Prerogative going forwards, but it’s origin ariies from constitutional convention? Have I not understood anything?

    This case does confirm that it is the common law of England, founded in the rule of law that allows the courts the final arbiter of whether a particular type of prerogative exists or not. Nevertheless, certain prerogative powers [1688 case of proclamations] have been widely acknowledged and accepted over time as being subject to review, while others have fallen out of use, so again this seems to suggest some form of convention, which is not justicable. Or is common law able to just fall into disuse, like a convention?

    So is this just yet another step towards the common law constitutional principles? I have deliberately avoided the grund-norm – or rule of regognition as I don’t undertand its application in English common law, which is all about interpretation as far as I understand.

    Thank you very kindly for your posts.

  2. A few clarifications Professor.

    No evidence of a constitutional convention which governs the matter of length of parliamentary prorogation. So matter could be justicable. Thank you for the clarity in explaing that the prorogation was not done by Parliament, by to Parliament through the use ofprerogative.

    Conventions supposedly deal with the relationship between constitutional actors – parliament, the queen, and the courts. The separation of powers require judicial restraint would have been appropriate so as not to trespass on another institution’s functions. You also mention the inconsistent application of separation of powers, Fire Brigades Union [1995] so is there still perhaps further clarification necessary from the court? I am not sure I quite understand the border of constitutional conventions in respect to justicability of the courts.

    What if the Government refuses to accept the prohibition on crashing out with no deal on 31st Oct. 2019. Can the courts get involved with enforcing an act of Parliament against an elected government? Is this justicable? Or is it regulated by convention?

Leave a Reply