Brexit and the relationship between the Crown and Parliament

On 3 November 2016, the Queen’s Bench Division handed down judgment in R (Miller) v Secretary of State for Exiting the EU. While the case has obvious practical significance for the Brexit process, for those of us on whom Britain’s leaving the EU would have no immediate effect, the decision is interesting primarily for its restatement of established principles of British constitutional law and for its application of those principles to a distinctly 21st-century problem.

The claimants in Miller sought a declaration against the defendant Secretary of State that the prerogative power of the Crown did not extend to giving notice under Art 50 of the Treaty on European Union of the United Kingdom’s decision to withdraw from the European Union. In support of their case, the claimants made two overlapping submissions

  • First, the claimants submitted that by reason of the incorporation of various treaty rights into UK domestic law by the operation of the European Communities Act 1972 (the ECA), withdrawal from the treaty would abrogate existing statutory rights. Because the Crown has no prerogative to alter existing legal rights, the claimants submitted, it followed that the ECA necessarily reserved to Parliament the power to determine whether the UK should withdraw from the treaty.
  • Second, in what was described as an “alternative submission”, the claimants submitted that the ECA’s transformation of treaty provisions into domestic law rights and liabilities impliedly revoked any pre-existing power of the Crown to withdraw from the treaty. This alternative submission involved a specific application of the well-established principle that once Parliament assumes control over a matter that formerly fell within the prerogative power of the Crown, the power is rendered wholly statutory in nature and “that in exercising such authority the Executive is bound to observe the restrictions which Parliament has imposed in favour of the subject.”

The Court held in favour of the claimants. In reaching its conclusion, the Court proceeded from the proposition that “it is a fundamental principle of the UK constitution that the Crown’s prerogative powers cannot be used by the executive government to diminish or abrogate rights under the law of the United Kingdom.” While this proposition now seems self-evident, the Court provided a valuable discussion of its history, referring to such seminal constitutional documents as the Case of Proclamations, Arts 1 and 2 of the Bill of Rights and Dicey’s Introduction to the Law of the Constitution.

It is somewhat difficult to tell which of the claimants’ two submissions was favoured by the Court. On the one hand, the Court’s statement that by enacting the ECA, Parliament intended to legislate for the domestic recognition of treaty rights “in such a way that this could not be undone by exercise of Crown prerogative power” suggests that the primary submission was adopted; on the other, the extensive discussion of such cases as Attorney-General v De Keyser’s Royal Hotel and R v Secretary for the Home Department; Ex parte Fire Brigades Union suggests that it was the claimants’ alternative submission that the Court accepted. Ultimately, it seems to me that the two submissions were fundamentally the same – at its heart, the case accepted by the Court was that Parliament’s adoption of treaty rights and obligations into the domestic law of the UK left no room for action by the Executive that would abrogate those rights and obligations.

The case is unlikely to have any specific impact on Australian law, although it will no doubt serve as a useful resource for Australian government lawyers interested in the history Parliamentary sovereignty in the Anglo-Australian constitutional tradition. The question how Australia might seek to withdraw from a treaty given domestic effect through legislation enacted in reliance on s 51(xxix) of the Constitution would raise additional questions that did not need to be considered in Miller, such as whether the Executive can withdraw from a treaty that Parliament has relied on as the source of its power to enact legislation pursuant to the external affairs power.

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