Abstract/Summary

In R (Miller) v Prime Minister (No. 2) the UKSC invalidated an attempted prorogation of Parliament, ostensibly because it was as an unjustified violation of the principles of Parliamentary sovereignty and government accountability. However, this article argues that the true basis of the Court’s decision was different: the court enforced what it perceived to be a constitutional convention sharply limiting the prerogative power to prorogue Parliament. This is a radical departure from the longstanding position of both courts and most scholars, which classified conventions among the rules of a political constitution that could not be enforced by the courts. Despite the Court’s description of its decision as a “one-off”, its reasoning may have far reaching implications. The tactic of describing real or putative conventions as instantiations of legal principles circumscribing the Crown’s prerogative powers can be used in future cases. Yet while the collapse of the distinction between the legal and the political constitutions would be a major constitutional innovation, the fact that a judicial decision would result in such innovation is hardly as shocking as the critics of Miller (No. 2) have suggested. In contrast with legal systems where the constitution is entrenched, United Kingdom’s courts shape its constitutional law, as they always have, subject to Parliamentary supervision. If their ability to do so is a concern ― and perhaps it should be, both to avoid judicial error and to limit the odds of the judiciary being dragged into damaging episodes of “constitutional hardball” ― the solution may well be to codify and entrench the constitution.