This article analyses the recent decision of the UK Supreme Court determining the UK’s ‘constitutional requirements’ for triggering Article 50 TEU. It demonstrates that the underlying disagreement in the case concerned the proper conceptualisation of EU law as it operates in the UK legal order. The Government and its academic supporters denied that EU law rights could be equated to domestic law rights; this allowed them to argue that their loss through withdrawal from the EU would not breach the long-standing prohibition on Executive prerogative action removing domestic law rights or altering domestic law. The article argues that the Supreme Court was right to reject this argument. In doing so, the Court emphasised that EU law had not only deeply infused the domestic legal order but had significantly changed it. Hence use of Executive powers to withdraw from the EU would amount to the Executive changing the constitution. The article considers how this ‘constitutional change’ argument – already strongly criticised – should be understood, and seeks to shed light on it via the notion that constitutional amendment is usually recognised as an exercise of especial normative significance. While acknowledging that the UK’s constitution lacks the formal process for such change required by other European states, it argues that the invocation of this principle in Miller may be related to recent developments in constitutional doctrine recognising the special status of fundamental constitutional rights and principles. In doing so, it argues for a significant change to our understanding of ‘constitutional statutes’.