Irrespective of whether you agree with the judgment – and, for many of the reasons detailed by other contributors, I regard it as mistaken – there is something slightly quizzical about how the High Court answered the question before it. As Aileen McHarg noted, the judgment is ‘a curious mixture of new and old constitutionalism’. (See also Paul Daly on this).

The ‘old’ embraces the Court’s endorsement of constitutional orthodoxies, including parliamentary sovereignty. (‘Parliament remains sovereign and supreme’ and ‘can, by enactment of primary legislation, change the law of the land in any way it chooses’). It is Bingham’s dicta in Jackson that is cited, not Steyn, Hope or Hale. The traditional lens of representative democracy dominates, with the EU referendum largely absent (the referendum was a ‘political event, the significance of which will have to be assessed and taken into account elsewhere’).

The ‘new’ includes the stress on the EC Act 1972 as a ‘constitutional statute’ which attracts more flexible (less disciplined?) interpretative approaches informed by (a very incomplete set of?) ‘background constitutional principles’. Formalistic interpretations are for the constitutional ash heap, replaced by new (strained and unconvincing?) legal fictions about what the 1972 Parliament intended. The multi-layered constitution is in plain sight (but not the powerful parallels with terminating treaty-based rights in double-tax treaties).

What is disquieting (for me) is that parts of the ‘old’ are employed (twisted?) to justify parts of the ‘new’, whilst the effect of the ‘new’ is to undercut the ‘old’. If invocations of the ‘old’ were intended to comfort and reassure, as well as to justify and persuade, they left me feeling cold.

Where does this leave us? Not for the first time of late I find myself recalling a character by the name of Mike Campbell in Hemingway’s The Sun Also Rises. Someone asks Campbell ‘How did you go bankrupt?’ Campbell replies that he went bankrupt two ways: ‘Gradually and then suddenly’. Yesterday’s decision suggests that something similar might be said about the constitution and the judicial roles within it. If our constitution is changing (in part because of changing judicial roles), it has done so gradually and suddenly – and, in many respects, it is the cumulative consequences of gradual change that normally concern me more. But yesterday’s decision is a sudden change of some significance. The Supreme Court should correct the High Court’s mistake and reassert the tried and tested good sense of the old constitution.

Graham Gee is Professor of Public Law at the University of Sheffield and Editor of the Judicial Power Project website.

Click here for further analysis of the Miller case.