The decision in in R (Miller) v Secretary of State for Exiting the European Union rested on the Sovereignty of the Parliament at Westminster. But the referendum was an expression of the will of the People. It is not at all obvious how these competing claims can be reconciled.

A Sovereign Parliament is free to make or unmake any law. Arguments which rely on the Sovereignty of Parliament necessarily imply that Parliament is free to set aside the referendum result.

In 1835 King William IV dismissed a Whig government which had not yet lost the confidence of Parliament. He did so because he ‘fancied that public opinion was leaving the Whigs…’. Bagehot argues that although the King had the power to act he was unwise to do so: his actions ‘looked inconsistent with the liberties of the People’ (Bagehot, 183). The Tories failed to win the resulting election. The episode ultimately highlighted the waning influence of the monarchy over the people – that weakened the institution of the Crown.

The experience of King William is a cautionary tale for Parliament. Some might fancy that public opinion is leaving the Brexiteers. Some might fancy that Parliament could act to prevent Brexit. In light of the High Court judgment in Miller it could be argued that a Sovereign Parliament would be free to do just that: but it would be unwise.

As Prof Bogdanor put it in The Telegraph, “Brexiteers wanted to re-establish the sovereignty of Parliament. But Parliament will now be constrained, not by Brussels, but by the British people”.

Parliament should rely on Miller to cautiously assert its authority. It should seek assurances but ultimately, if and when it is asked, it should trigger art. 50. To do otherwise would be to risk appearing ‘inconsistent with the liberties of the People’ and that would be risky.

Fergal Davis is a Reader in Public Law at The Dickson Poon School of Law, King’s College London, and a Senior Visiting Fellow.

Click here for further analysis of the Miller case.