On November 3, a three-member panel of the High Court of Justice’s Queen’s Bench Division ruled that government ministers do not have the unfettered right to trigger the United Kingdom’s withdrawal from the European Union by submitting notice under Article 50 of the Treaty on European Union. In a strongly worded opinion citing English case law from as far back as the early 1600s, the court concluded that longstanding constitutional arrangements limit the Crown’s—and therefore ministers’—“prerogative powers” to alter UK domestic law unilaterally. In defense, the government argued that the Article 50 notice represented the exercise of the Crown’s traditional prerogative powers in the field of international relations to conclude treaties. However, the judges were persuaded by the claimants that the act of submitting an Article 50 notice would lead inevitably to the UK’s withdrawal from the EU, which would necessarily cause the rights afforded to UK citizens under EU law— which form part of UK domestic law due to the European Communities Act 1972 (ECA)—to be withdrawn, and on matters of UK domestic law Parliament is sovereign.

In the contest between the Crown’s prerogative powers and the sovereignty of Parliament, the judges relied on the constitutional principle that, unless Parliament legislates to the contrary, the Crown does not have the authority to alter UK domestic law through its prerogative powers. The court then found that, in relation to statutes of “special constitutional significance” such as the ECA, there is a heightened burden in demonstrating Parliamentary intent to permit the Crown to unilaterally exercise its prerogative powers. Finding no evidence of such intent, the court then held that the Crown must give way to Parliament. The court did not, however, specify the form of relief to be granted. The government has announced that it will appeal the court’s ruling; the case has been fast-tracked to the UK Supreme Court, which is expected to hear arguments in early December.

The judgment in the case R (Miller) v. Secretary of State for Exiting the EU is available here.