Brexit: When politics and the law collide – a UK Supreme Court decision

In a decision that received widespread international media attention, the UK Supreme Court ruled in R (Miller) v The Prime Minister [2019] UKSC 41 that a decision to prorogue (i.e. suspend) the UK Parliament for five weeks was unlawful.

The ostensible purpose of the prorogation was to prepare a Queen’s speech and a legislative program for a new session of Parliament. The English High Court held that the prorogation of Parliament was not justiciable (i.e. not capable of challenge in the Courts). They referred to various decisions where the Courts ruled that certain prerogative powers were not susceptible to judicial review, due to their nature and subject matter.

Traditionally, the Courts do not interfere where exercises of prerogative power involve matters of “high policy” or are “political”. The reason for this is partly because of the separation of powers - it is for the Executive, not the Courts, to govern - and partly because political matters require political, rather than judicial, resolution. In previous cases, the Courts have said that the function of the Courts is to adjudicate on the rights and obligations of individuals, not on political matters. The High Court said that “political” issues are characterized by an absence of judicial or legal standards by which to assess the legality of the Executive’s decisions.

The High Court considered that the decision to prorogue Parliament at that particular time and for that duration was political, with a number of “intensely political considerations” taken into account. It was not able to make a legal assessment of whether the prorogation was excessive. There had been a number of occasions in the twentieth century when Parliament had been prorogued for several months, sometimes for political advantage. Therefore, the Court could not assess by any measurable standard how much time the Government could legitimately spend on preparations for its legislative program, or how much time Parliament needed to hold the Government to account.

On appeal, the UK Supreme Court approached the matter in a less orthodox way. The authorities which the High Court had relied on to explain why the Courts do not interfere in political matters were not deeply analyzed. The Court said that the separation of powers, a core constitutional principle, would be upheld by ensuring that prorogation was not used unlawfully; the judicial function was to determine the legal limits of the powers conferred on each branch of Government, and the Courts must do this even though the questions raised were political. The Supreme Court then went further, finding that Parliamentary sovereignty would be undermined if the Executive could, through the use of the prerogative, prevent Parliament from exercising legislative authority. The Supreme Court defined the relevant test as being whether prorogation prevented, without reasonable justification, the ability of Parliament to carry out its constitutional function as a legislature responsible for supervising the Executive.

In reaching these conclusions, the Supreme Court fashioned a wider principle of Parliamentary sovereignty. The High Court had earlier described this idea as “novel”, and criticized it as an invitation for judges to “ … exercise hitherto unidentified power over the Executive branch of the state in its dealings with Parliament”. It also meant that the Supreme Court had to consider the very same (arguably political) reasons for prorogation that the High Court found itself unable to assess. The Court concluded that the prorogation “ … was not a normal prorogation in the run-up to a Queen’s Speech”.

That the UK High Court and Supreme Courts could reach such different conclusions on a fundamental issue is startling, and the outcome heralds a greater willingness to intervene in areas previously considered non-justiciable. At the very least, the line delineating the separation of powers - reflecting the different constitutional areas of responsibility of the Courts, Executive and Parliament - has arguably become rather blurry. The UK judiciary is already facing calls for more political scrutiny as part of their appointment process, as in the US.

The decision also has potential implications for New Zealand, although a decision of the UK Supreme Court is no more than a persuasive authority. But the constitutional principles at play are analogous, for example under the Constitution Act 1986, the Governor-General has power to dissolve or prorogue Parliament, and the Governor-General must, by convention, act in accordance with the advice of the Executive Council.

Faced with a legal challenge to the prorogation of Parliament, or other exercise of prerogative powers involving political considerations, how will our Courts react?