Abstract: | The Miller case concerned the constitutional requirements for the UK to give notice of its intention to withdraw from the EU pursuant to Article 50 of the Treaty on European Union. The parties made submissions in terms of two competing syllogisms. The Government argued that ministers, exercising Crown prerogative, had the power to give notice without statutory authorisation. The Applicants argued that the process required authorisation by Act of Parliament because the UK's withdrawal would deprive people of rights arising under EU law. However, a majority of the Supreme Court decided in favour of the Applicants based on a third and significantly different syllogism, based on the proposition that the European Communities Act had established EU law‐making and law‐interpreting institutions as new ‘sources of law’. This note assesses the three competing syllogisms and examines the constitutional significance of the majority's proposition that these new EU sources of law were integrated into UK domestic law without disrupting the principle of parliamentary sovereignty. |