Today’s ruling marks the latest chapter in the struggle between the Crown and a democratically elected legislature.

So now we know. A powerful court consisting of the lord chief justice of England and Wales, the master of the rolls and Lord Justice Sales has concluded: ‘…the secretary of state does not have power under the Crown’s prerogative to give notice pursuant to article 50 of the TEU for the United Kingdom to withdraw from the European Union.’ (para 111)

Article 50 states that notice must be given according to the constitutional requirements of a member state. Everyone agreed that the court could determine what the UK’s constitutional requirements were.

The secretary of state acknowledged that, when the Crown’s notice took effect, existing EU law and treaties and provisions of the European Communities Act 1972 would be stripped of their effect in domestic law. The judgment identifies three sets of rights that would be lost: those in the UK, those in other EU member states and those in EU institutions.

Such a dramatic result could be justified because, it was said, parliament had always intended that these rights should be conditional on continued EU membership. Continued EU membership was always intended to depend upon the actions of the Crown in international law. So the prerogative, available in the sphere of international law, could be used to give notice.

The claimants had not shown that parliament had intended the prerogative to be inapplicable.

The court’s response to these submissions was polite but firm. It said they ‘left out part of the relevant constitutional background’ (para 84). They were ‘flawed at this basic level’ (para 85). They ‘gave no value to the usual constitutional principle that, unless parliament legislates to the contrary, the Crown should not have power to vary the law of the land by the exercise of its prerogative powers.’ (para 84)

The Crown can use these powers only on the international plane and not to alter domestic law. The European Communities Act 1972 did not reserve power to the Crown to act internationally or serve notice.

The submissions on behalf of the secretary of state did not stand up. Nevertheless, the court went on to agree with the claimants that the Crown needed authority under an Act of Parliament to change domestic law and nullify rights. It did not have it, expressly or impliedly. So, ‘on this further basis’, the secretary of state’s failure was confirmed.

In 1995, Lord Browne Wilkinson said: ‘The constitutional history of this country is the history of the prerogative powers of the Crown being made subject to the overriding powers of the democratically elected legislature as the sovereign body.’ (Ex p. Fire Brigades Union [1995] 2 All ER 244, 254d).

In this judgment the court has written another chapter in that history. It is clear and cogent. Those who want direct, instead of representative, democracy will disagree with it. Before the Supreme Court, which will hear the appeal in December, much more than Brexit is at stake.

Dr Timothy Lyons QC is a barrister at 39 Essex Chambers