The case at a glance

R (Miller) v The Prime Minister; Cherry v Advocate General for Scotland [2019] UKSC 41 (UK Supreme Court, unanimous, eleven Justices). Holding: the advice to prorogue Parliament was justiciable and unlawful; the prorogation was void and of no effect.

The story

In the tensest months of the Brexit process, the Prime Minister advised Her Majesty to prorogue — suspend — Parliament for approximately five weeks, an unusually long period at a moment of exceptional constitutional consequence. Challenges were brought in England by Gina Miller and in Scotland by Joanna Cherry MP and others, contending that the true purpose and effect was to prevent Parliament from scrutinising the executive at precisely the time scrutiny mattered most.

The question

Is the prerogative power of prorogation subject to legal limits at all — and if so, had those limits been crossed?

The decision

A unanimous Court held that the courts can determine the limits of a prerogative power — that question is one of law, not politics — and articulated the standard: a decision to prorogue is unlawful if it has the effect of frustrating or preventing, without reasonable justification, the ability of Parliament to carry out its constitutional functions of legislating and holding the executive to account. On the evidence, the five-week prorogation had exactly that effect, and no justification — indeed, no reason — had been put before the Court. The advice was unlawful; the prorogation was as if “the Commissioners had walked into Parliament with a blank piece of paper”; Parliament had never been prorogued at all.

Why it still matters

Miller (No 2) is the modern common law’s clearest statement that no exercise of governmental power is above legal accountability, and that constitutional principles — parliamentary sovereignty and parliamentary accountability — can themselves supply the standard of review. For readers in any Westminster-influenced system, Bangladesh included, it is a masterclass in how unwritten constitutional principle becomes enforceable law, delivered under the highest political pressure imaginable, unanimously.