The government has a good chance of winning the Brexit Supreme Court appeal – here's why

The High Court’s decision in the Article 50 litigation (R (Miller) v Secretary of State) illustrates the tension between the rule of law, the democratic will and the place of our representatives to determine it. Put another way, between the judiciary, the electorate and Parliament.

Who has the authority and who the legitimacy to make decisions of such magnitude as Britain’s membership of the European Union? How may those decisions be made? And who must arbitrate when the powers of government and Parliament and the effect of the decision of the people, in a referendum, are in doubt?

That final question answers itself. A strong and independent judiciary, able not only to determine complex questions of law but to do justice for the weak against the strong, is the cornerstone of a society of laws. Judges have an onerous responsibility. They are not the “enemies of the people” but the guardians of their rights. They must balance the relationship between people, government and Parliament. Yet they are fallible and will always disappoint some. To attack judges or litigants personally is the behaviour of the demagogue, not of mainstream newspapers or democratic politicians.

So the judiciary cannot be blamed for determining the limits of the authority of the Crown, the role of the people and the power of Parliament. But that is not to say that they – or their power – are beyond criticism; nor that criticism of judgments is in some way contrary to the rule of law. Far from it. Open – even distasteful – debate is the lifeblood of a stable society.

These tensions could not be more heightened than they were in Miller. The referendum it concerned was authorised by an Act of Parliament introduced by a government elected on a manifesto commitment to follow its result; it was enacted on the express understanding that the government (not Parliament) would withdraw in the event of a Leave vote; and the prime minister, during the campaign, undertook to give notice under Article 50 in that event. Save for one reference to the legal effect of a referendum being advisory in a House of Commons paper, the intention of Parliament was to delegate the decision to the electorate.

Yet the political argument of the claimants has been to represent themselves as the champions of Parliamentary sovereignty; occasionally expressed in opposition to “popular democracy”. It is suggested that ensuring that Parliament has a vote before notification – a process that will lead inevitably to the United Kingdom leaving the European Union – would be to allow the government to defeat rights accrued by membership of the Union, including rights that could not be replicated outside it.

This argument succeeded in its legal form. The government’s freedom to operate in the “international plane” by terminating the EU Treaties was, the Court found, abrogated by the European Communities Act 1972, whether or not the 1972 Act expressly withdrew that prerogative power. Notification would have the inevitable result of terminating “statutory” rights and so could not be done without Parliamentary approval.

The government’s legal argument can be put simply. Only the Crown has the power to act internationally; only the government can make or terminate treaties. Indeed, the Court recognised that “the Crown’s prerogative power to conduct international relations is regarded as wide and outside the purview of the courts precisely because the Crown cannot, in ordinary circumstances, alter domestic law by using such power to make or unmake a treaty.” (Paragraph 32)

An important part of the government’s argument – though given little weight in oral argument – was that rights conferred by Acts of Parliament dependent upon the UK being a party to treaties can be and have been varied and even removed by the government. A particular example is the right not to be subject to “double taxation”, which, though enshrined in domestic law, are vulnerable to being terminated not only by the government but by foreign governments. This argument is supported by Professor John Finnis, Professor Mark Elliott and Professor Paul Craig.

So it is by no means certain – despite the strength of the High Court (effectively the Court of Appeal in all but name and containing its two most senior judges) – that the government’s appeal will fail.

Yet what is the true legal effect of this decision? The control that the Court has declared Parliament to have is extremely limited: no more than that only it may authorise notification of withdrawal from the EU by the government. While an Article 50 notification might contain expressions of objectives, these could not bind the Government acting on the international plane. Moreover – as the Court acknowledged – even if objectives set out in an Act of Parliament could bind the government, the negotiations are wholly outside Parliament’s hands. Ultimately, Parliament will be limited to authorising withdrawal and to authorising or to rejecting, but probably not to amending, the deal agreed with the European Council.

And what of the political effect? Parliament has already enacted a referendum on the understanding that it would respect the will of the people. The only decision that the people have made is to leave the EU and the only way in which it can be put into effect is through notification by Article 50. So Parliament has had its sovereignty “restored” in order to choose between respecting the result of a referendum it legislated for or to ignore it. It may do no more.

A grand and important assertion of Parliamentary sovereignty? A grubby attempt to thwart the will of the people? Or a damp squib?

Francis Hoar is a barrister specialising in public law.