Richard Ekins’ ‘What the PM gets right about the Brexit litigation‘, was first published on the Reaction site on 5 October 2016.

The Government’s legal authority to invoke Art 50 is being challenged in the courts. In her speech on Sunday, the Prime Minister stated in strong terms that it is up to the Government – not the Commons or Lords – to invoke Art 50. Those who argue the contrary are not standing up for democracy, she said, but seeking to subvert it, insulting the intelligence of the British people and aiming to kill Brexit by delay. Is she right? Does it matter?

The Art 50 litigation has sometimes been presented, cannily, as a defence of parliamentary sovereignty against an over-mighty, unelected executive. The claimants may well believe, in good conscience, that democracy requires Parliament to second-guess the referendum result. However, the basic point of the litigation is not to avoid executive tyranny or to promote democracy but rather to introduce a new stumbling block, to delay Brexit, and to provide sympathetic MPs and peers with an opportunity to frustrate the referendum result.

If the concern were to ensure that the Government did not begin to remove the UK from the EU without parliamentary approval then the litigants would be content to bring political pressure on the Government to seek resolutions of each House of Parliament before acting.

As the Prime Minister implied, there is now no constitutional need for express parliamentary approval – Parliament enacted the European Union Referendum Act 2015 and thereby chose to put the question of whether to leave to the British people on the clear understanding that the vote would be decisive. The Government does not act improperly if it now honours that undertaking.

True, the Government is accountable to Parliament for its actions in relation to Art 50 and in extremis the Commons could unseat the Government if it had no confidence in its plans. Litigation is not needed for Parliament to be able to hold the Government to account or even to block Brexit altogether if it wishes.

But what the litigation would achieve, if successful, is significant delay. The Government would need to persuade the Commons to support legislation authorising it to begin the process of Brexit and might need to invoke the Parliament Acts 1911 and 1949 to overcome resistance in the Lords, which would add at least a year to the timetable.

This would likely embolden some MPs and peers to try to thwart the Government’s intention to honour the referendum result. It would also outrage the electorate, further undermining political trust, and encouraging criticism of the judiciary for having helped frustrate the public’s decision.

However, the Art 50 litigation is not about democratic principle so much as about the demands of the rule of law. The claimants insist that without the authority of an Act of Parliament the Government simply has no legal power, to initiate Art 50. They insist that in this context the royal prerogative to conduct foreign policy has been overtaken by legislation.

This is a clever argument but it is also clearly wrong. The royal prerogative authorises the Crown, accountable always to Parliament, to commit the UK to treaties, to withdraw from them, and more generally to represent the UK in the international realm. Parliament could legislate to restrict this power but in this case it has not done so.

The European Communities Act 1972 presupposes that the prerogative has not been limited – that the Crown retains the power to conduct foreign policy. Parliament has since enacted particular restrictions on this power, mostly to prevent the Government from expanding EU powers without parliamentary approval. These restrictions confirm that the 1972 Act did not supplant the prerogative and that the Government otherwise remains free to act.

The best case for the litigants is to draw strained analogies with established constitutional principles. It is true and important that the executive cannot suspend statutes and that it cannot change domestic law by fiat. But this in no way makes it unlawful for the Crown to convey to the European Council the UK’s decision to leave the EU: this decision has consequences, eventually, for our domestic law only because of the terms of existing British statute.

The courts should dismiss the argument that the 1972 Act limits the prerogative. The litigation is anti-democratic in that it seeks to frustrate the public’s decision by way of judicial action. But this is not why the courts should reject it. The duty of the court is to help maintain the rule of law, which here means respecting the established legal position that the Government has the power to act. The judges should adhere to that position even if they wrongly think that democracy would be better served if Parliament were required to affirm or undo the referendum result.

If the courts uphold the rule of law, they will not lend their authority to an undemocratic challenge to the Government’s clear legal power to implement the outcome of the referendum.

Prof Richard Ekins leads Policy Exchange’s Judicial Power Project