Boris Johnson. Picture: REUTERS/PHIL NOBLE
Boris Johnson. Picture: REUTERS/PHIL NOBLE

Brexit has rewritten many rules of the game for British politics and constitutional law. It has just added another chapter of great importance to this saga.

On September 24 the supreme court of the UK ruled in a unanimous judgment by all eleven supreme court judges that Boris Johnson’s prorogation of parliament was unlawful. Commentators described this as a “stunning defeat” for the prime minister.

Johnson has been UK prime minister since July 24, after Theresa May resigned. Parliament repeatedly rejected her draft agreement to implement the 2016 British referendum result, adopted by a majority of 51.89%, to leave the EU.

After his election as premier, Johnson announced he will try once more to secure a new withdrawal agreement but if that fails, the UK will exit from the EU by end-October, “come what may”. Brexit would then occur by default because the latest extension by the EU to conclude a withdrawal agreement and secure an “orderly Brexit”, expires on October 31. He was adamant that no further extensions would be requested.

Exiting without a withdrawal agreement — and without the two-year transition period in which to work out the future EU-UK relationship — is known as a “hard Brexit”. Under this scenario, UK companies will immediately start trading with the EU, the UK’s most important trading partner in goods as well as services, and with the rest of the world under the more stringent rules and higher tariffs of the World Trade Organisation (WTO).

He strongly objects to the backstop provision in May’s draft withdrawal agreement but has limited time and not much enthusiasm to work out new proposals to address a very complicated matter

New preferential trade agreements would have to be negotiated from scratch, a process that can take years. (The recent trade deal between the EU and Canada took seven years to finalise.)

Most British MPs are against a hard Brexit. In early-September an alliance of opposition MPs and Conservative rebels passed a law that requires the government to seek an extension to the UK’s EU membership if he fails to secure a Brexit deal at the EU Council meeting of October 17-18. Under the Benn Act (proposed by Labour MP Hilary Benn) Johnson must ask for an extension if he fails to secure parliamentary approval for a Brexit deal by October 19.

That put Johnson on a collision course with parliament. He strongly objects to the backstop provision in May’s draft withdrawal agreement but has limited time and not much enthusiasm to work out new proposals to address a very complicated matter.

He must convince the EU that his plan for future customs procedures at the border between Northern Ireland and the Irish Republic will properly cater for post-Brexit needs, under which there must be borders between the EU and the UK, as well as sufficient freedom of movement to preserve the peace in Ireland.

If Brussels cannot be satisfied, there will not be an orderly Brexit. And there will be a hard border between Northern Ireland and the Republic of Ireland. The Good Friday Agreement, which in 1998 put an end to 30 years of Northern Ireland’s troubles, will be in danger. A hard Irish border after Brexit threatens the Irish peace process.

Not justiciable

But Johnson had a plan. At end-August he requested the queen to prorogue parliament from September 9 to October 14. This prompted an uproar from the Commons, especially from MPs who had planned to block a no-deal Brexit. Court applications to set aside the prorogation of parliament followed in the high court of England and Wales and in the Court of Session in Scotland.

The question was whether the advice given by the premier to the queen that parliament should be prorogued was lawful. The high court of England and Wales ruled that since the power to prorogue parliament is a prerogative, it is not justiciable in a court of law. The merits cannot be examined.

The Court of Session ruled the opposite. It found that the premier’s decision was motivated by the improper purpose of stymieing parliamentary scrutiny of the government. Any prorogation that followed it is unlawful, void and of no effect. Both these judgments were appealed in the UK supreme court.

What is the prerogative about? The term royal prerogative refers to powers that are unique to the sovereign. They belong to the monarch but are exercised by the premier. They have traditionally been viewed as of high political nature and not reviewable in a court of law.   

How did the UK supreme court decide these appeals? The premier’s lawyers followed the traditional path and simply argued that the prerogative is never justiciable. The courts would enter a “minefield” if they would rule over the exercise of prerogatives. The other side wanted the court to determine the lawfulness of the prorogation of parliament.

The supreme court was at pains to emphasise that this case was not about when and how the UK leaves the EU. The only issue was whether the advice given by the premier to the queen that parliament should be prorogued, was lawful; and the legal consequences if it was not.

The first question was whether the lawfulness of the premier’s advice to the queen was justiciable. This court held that it was. It did not say that the premier had an improper motive of stymieing or frustrating parliamentary scrutiny. The supreme court did not find that the prerogative has no place in the constitution.

It ruled that there are limits to the power to advise the monarch to prorogue parliament. If the prorogation has the effect, without reasonable justification, of frustrating or preventing parliament to carry out its constitutional functions, it is unlawful. The prerogative is, therefore, justiciable.

The court noted that proroguing parliament is quite different from a parliamentary recess. While parliament is prorogued, neither house can meet, debate or pass legislation, and members may not ask written or oral questions of ministers or meet and take evidence in committees.

During a recess the House does not sit but parliamentary business can otherwise continue as usual.

The recent prorogation also took place in exceptional circumstances: the fundamental change that Brexit will bring about to the constitution of the UK. Parliament, as the elected representative of the people, has a right to a voice in how that change comes about. The effect of Brexit upon the fundamentals of British democracy was extreme.

No justification for taking the extreme action of suspending parliament at such a crucial moment has been put before the court. It was bound to conclude that the decision to advise the queen to prorogue parliament was unlawful because it had the effect of frustrating or preventing the ability of parliament to carry out its constitutional functions without reasonable justification.

What remedy was ordered? The court found that since the premier’s advice to the queen was unlawful, void and of no effect, parliament has not been prorogued. It is for parliament, and in particular the speaker, to decide what to do next. The speaker immediately announced that parliament would meet again the next morning — and Johnson took an overnight flight back from New York.

Where does this ruling leave the Brexit process? Johnson is still in a defiant mood. The judgment will be respected, he says. But Brexit happens at end- October. How this will come about remains unclear.

He also wants an early election but does not have the required majority to make that possible.

The next notable deadline is October 19, when parliament must decide whether a new withdrawal agreement, secured by Johnson, can be adopted or whether a completely new parliamentary initiative is necessary.

• Erasmus is an associate at the Trade Law Centre.