Britain’s confusion over Brexit highlights the difficulties that can arise when constitutional principles are unclear, writes Sir Geoffrey Palmer
The Divisional Court on 3 November 2016 decided that the UK Government could not use the royal prerogative power to give notice of withdrawal under Article 50 of the Treaty of the European Union: R (Miller) v Secretary of State for Exiting the E.U.  EWHC 2768 (Admin).
The three Judges who decided the case were the Lord Chief Justice for England and Wales, the Master of the Rolls and a Lord Justice of Appeal. This is a bench of top-line legal talent.
The outpouring of intemperate criticism of their decision from the British media was remarkable. The judges were attacked in the media for interfering in matters beyond their competence, for being undemocratic, elitist and out of touch.
Ministers were upset and the Government has appealed the decision. MPs spoke out against the decision.
It took an embarrassingly long time for the Lord Chancellor to issue a statement defending the Judges and upholding the basic constitutional principle of English law, the independence of the judiciary. Later, other MPs defended the judges.
One might well have wondered what had happened to the rule of law value in the barrage of criticism.
As well, what happened to the principle that Parliament is supreme, not the Executive?
Are people applying to the court to be denied justice on a real legal issue for reasons of political expediency?
There was a real legal issue involving real constitutional law, even under the United Kingdom’s unwritten Constitution.
Once notice of withdrawal was given, the court said, it would inevitably result in the complete withdrawal of the United Kingdom from the EU.
The European Communities Act 1972 gave direct effect and primacy to EU legislation over domestic primary legislation.
And since the 1972 Act had been regarded as “constitutional” in a previous decision, it was not subject to the doctrine of implied repeal.
So although there had been a referendum conducted under a 2015 statute in which a majority of voters had voted to leave the EU, the foreign relations power of the Crown, exercised by Ministers under the royal prerogative, could not be used to give notice. The court so held in a unanimous decision.
The reason was because people had rights that would be taken away. The European Union provided by virtue of UK membership a category of rights to British citizens against other member states, such as rights to freedom of movement and of capital. These rights could be enforced in the courts of member states.
New Zealand lawyers have it seared into their legal souls that a Prime Minister cannot suspend an Act of Parliament using royal prerogative powers. The Act has to be repealed by Parliament itself. Any suspension of law without the consent of Parliament is contrary to the Bill of Rights 1688 which is part of New Zealand law as it is of English law.
When Prime Minister Muldoon tried to suspend superannuation legislation after a general election the Chief Justice Sir Richard Wild held that his action was illegal.
After the celebrated case Fitzgerald v Muldoon  2 NZLR 615 was decided in 1976, there was no appeal. Costs were awarded against the Prime Minister.
The issues involve hard law, not constitutional custom or convention.
The case, one of the few relevant precedents available, was cited with approval in the recent English case.
The New Zealand case contained “the powerful constitutional principle that the Crown has no power to alter the law of the land by use of its prerogative power…”
EU rights had been incorporated into English law by European Communities Act 1972. If they were to be removed it would have to be by Parliament not the royal prerogative.
The judges held that state of the law meant the Crown had no prerogative power to give the notice. It was a matter for Parliament.
The bedrock principle of the British Constitution is “the supremacy of the Crown in Parliament”.
Parliament is the supreme law-maker. It has the right to make any law whatever and, as Professor A V Dicey said long ago, no other person or body can set it aside. The Crown is bound by it.
After the UK passed the European Referendum Act 2015 the Government did little work on what would happen if the referendum favoured exit. Indeed, Ministers apparently forbade public servants from doing any work on the subject.
The referendum was what we in New Zealand would call an indicative referendum. It did not itself have any legal effect.
In New Zealand, when we make constitutional changes by referendum the legal effect of the vote is made clear in the legislation itself. This happened with MMP and the flag referendum. The precise legal effects if the British voted “No” was not clear.
There are a number of lessons that can be drawn from this decision that have implications for New Zealand’s constitution.
First, the range of the royal prerogative is uncertain and a potential source of power to ministers.
In relation to foreign affairs and defence those powers are strong.
In our proposed new constitution Andrew Butler and I propose to abolish the royal prerogative and replace it where necessary by powers contained in Acts of Parliament agreed by Parliament.
Second, Executive governments always look for power where they can find it. That is what British ministers did here. It was inconvenient and awkward for them to go to Parliament. So they tried to prevent it.
Ministers in the UK are faced with the problem that despite the outcome of the referendum there may be a majority at Westminster for remaining in the UK. Avoiding a vote in Parliament by relying on the royal prerogative was an escape hatch.
The same temptation should be removed for New Zealand. Parliament is the central democratic institution, not Cabinet.
Third, our proposed constitution limits the powers of the Cabinet, by ensuring that Parliament must agree to the the State being bound by any treaty. That agreement should not be restricted, as it is now in New Zealand, to changing the law to ensure New Zealand can carry out the terms of the treaty.
Parliament has never voted in New Zealand for the Trans Pacific Partnership Agreement despite the fact that legislation allowing ratification will be put through the Parliament soon, a surprising decision since the TPP is dead after the Trump victory in the United States election.
There is a difference between Parliament voting on legislation necessary to implement a Treaty that may or may not not require changes to domestic law and voting on whether as a matter of principle it approves of the agreement in issue.
Fourth, the British decision and the reaction to it shows how little even informed people in the UK understand about their own constitution. What happened in 1688 is not easily brought to mind.
If the constitutional arrangements of the UK could be found in one authoritative place such an argument would never have needed to take place. A written constitution would have removed the apparent confusion.
The Economist in the issue of 12 to 18 November 2016 in a leader complains that the “haziness of Britain’s unwritten constitution contributes to the confusion around the ruling”.
In the same edition of the paper the columnist “Bagehot” argues: “Better, surely, to confront all the interlocking quandaries in one big public discussion leading to reforms and perhaps written constitution.”
The decision of the three judges sitting in the High Court is in my view an orthodox application of British constitutional law and correct. The prospects of it being reversed in appeal appear to be unlikely.
Parliamentary action will be necessary.