The majority of the Supreme Court in Miller decided to uphold the High Court judgment. They did so relying mainly on their construction of the European Communities Act 1972. This was the right approach to take, but the majority executed it in ways incompatible with established principle. The better analysis was offered in Lord Reed’s dissent. Here, I want to stress two particular ways in which the majority went wrong: (1) their use of the principle of legality and (2) their anachronistic approach to legislative interpretation.

The majority admitted that Parliament could have decided in the 1972 Act to give effect to Community/EU law on a conditional (‘ambulatory’) basis as argued by Professor Finnis and me in our respective papers for the Judicial Power Project. However, one is struck by the majority’s suggestion that this could have only been done by express words. This is supposed to follow from the principle of legality as discussed by Lord Hoffmann in Simms.

Used properly, the principle of legality is not a mechanistic formula according to which there must be express words in a statute recognising every effect that a statute has on any given rights. The real issue is whether an intent to effect a particular legal change can be attributed to Parliament. This is, to a significant extent, a function of the background law against which Parliament is legislating. And here comes the majority’s second sin: they seem to reconstruct the 1972 Act in the light of the current understanding of its significance, and not that of Parliament that enacted it.

As I argue in a recent Judicial Power Project publication, when understood in the context of the background law and the concerns the lawmakers had at the time, Part I of the 1972 Act is properly to be construed as preserving the Crown’s traditional role in the international realm by making direct effect of any EU laws and rights conditional on the UK’s international obligations.

Mikołaj Barczentewicz is a DPhil candidate in law at University College, University of Oxford. He specialises in legal theory and in UK public law and has published on the relationship between UK law and EU law.

Click here for further analysis of the Supreme Court’s Miller judgment.