Constitutional specialist and former Prime Minister Sir Geoffrey Palmer says British Prime Minister Boris Johnson's biggest error in the case over proroguing Parliament was not to offer the Supreme Court any reason for his decision.
Palmer said Britain was in a delicate constitutional crisis which could result in the breaking up of the United Kingdom.
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Former Attorney-General Christopher Finlayson says to court seemed determined to make a ruling that wandered into the heart of politics, but he said it would be harder for that to happen in New Zealand because of a law passed in 2014.
Proroguing of Parliament - suspending all proceedings of an elected Parliament before a new session starts up - has not happened in New Zealand for many years although it is still in the law.
Palmer has been following the roller-coaster events of Brexit closely including last week's decision by the Supreme Court to declare the proroguing of Parliament unlawful.
"This was rapidly done and not well considered," he said. "But the main error that the Prime Minister of the United Kingdom made was not to put forward the reasons for it.
"They were not wanting to offer any targets so they didn't offer any reasons for it and the absence of reason is never very appealing to a judge."
The Johnson Government has said the court had developed new law as it was entitled to do but it did not agree with its decision.
It was a decision which surprised Palmer along with most constitutional experts.
Palmer had predicted the court would declare the issue not justiciable, or outside its authority to rule upon.
"I was reasonably surprised that they did not but I do understand the reasons they did not because the British constitution is based on the idea of parliamentary sovereignty, a proposition which is a really more a political proposition than a legal proposition, because there aren't many cases supporting it as a doctrine, explaining it any authoritative way.
"But it is regarded as a keystone of the British constitutional system and they really couldn't deny the centrality of Parliament, having defeated the Theresa May Government on a similar issue."
Palmer was referring to a case brought by British businesswoman Gina Miller who took a case upheld by the Supreme Court in 2017 requiring a parliamentary majority to trigger Article 50 of the Treaty on European Union, the first step to take Britain out of the European Union.
"I think this is going to be paralysis for some time," said Palmer. "They've had three years of paralysis and they are no closer to a solution now than they were then.
"Every constitutional lawyer I know is absolutely obsessed with Brexit and I include myself in that category."
Palmer also has a connection to one of the judges – many years ago he taught comparative constitutional law at the University of Virginia to Lord Phillip Brodie, one of the judges in the Scottish court whose decision on prorogation the Supreme Court upheld last week.
"This is a very, very delicate constitutional crisis that Britain is in."
"They've had polarisation of an extraordinary sort. The body politic in the United Kingdom is suffering and it is quite possible that the United Kingdom may break up as a result of this," Palmer said.
"This is constitutionally extremely worrying and if you are interested in stable western democracies, there's not a lot on offer around the world right now."
Proroguing Parliament is not the same as a recess, during which select committee business can continue to be conducted.
Dissolution of Parliament happens shortly before an election.
In prorogation, MPs continue in their jobs but parliamentary business stops until a new Parliament is opened and it can happen within the same session of Parliament.
The prorogation proposed by Johnson of 34 days was long compared with previous ones, but when the usual recess allowed during party conference time in September was taken into account, it was only seven days that would have been lost, according to a memorandum from an official in Johnson's office.
Proroguing Parliament is deemed a "Royal Prerogative," one which was an inherent power of the Crown before parliamentary supremacy in 1688.
These days is it actually a Prime Minister's decision, and is rubber stamped by the Crown on the advice of the PM or ministers.
In Britain it is part of the common law and is done by an order-in-council.
In New Zealand it is set out in the Constitution Act and takes effect either by a notice in the Gazette or by a verbal proclamation in the presence of the Clerk of the House and two others.
Reasons have never had to be given.
Because it involves the start and finish of Parliaments, it has often been regarded as a proceeding of Parliament – which is off limits to the courts under the accepted separation of powers.
But Britain's Supreme Court said it was a government decision, not a parliamentary proceeding, and therefore justified its decision to examine the matter.
Finlayson said he was surprised by the decision and believes the Parliamentary Privilege Act may have made it hard for any court in New Zealand to go that far.
"I am really quite surprised by that decision. It really is getting into the realm of politics.
"Once you have got judges opining on what are intensely political matters, and I wouldn't have thought it was a justiciable matter, regardless of whether they say it is a one-off, you are heading down the path of the United States' Supreme Court model.
"I would hate to see judicial appointments politicised in the United Kingdom and New Zealand like they are in the United States."
Finlayson is wary of accepting the court's argument that proroguing Parliament is not a parliamentary proceeding.
"I just think that is attempting to make that which is at the very heart of the House of Commons something that the courts can look it. I find their explanation peculiar."
Finlayson believed that prorogation would meet the definition of a parliamentary proceeding under the Parliamentary Privilege Act passed in 2014 – and therefore be off limits to the courts in New Zealand.
Section 10 says: "Proceedings in Parliament, for the purposes of Article 9 of the Bill of Rights 1688, and for the purposes of this act, means all words spoken and acts done in the course of, or for purposes of or incidental to, the transacting of the business of the House or of a committee."
On the issue of whether the British decision lent support to it having a written constitution, Finlayson says it would have made no difference.
"They were determined to make their rulings and they have wandered into politics.
"This is a political mess that has been created by politicians and I can't see how the judges can get people out of it. Britain has got to suffer the consequences."
Palmer, one of New Zealand's leading proponents of a written constitution, said the issue had renewed debate in Britain over a written constitution.
"I actually think this is going to predicate constitutional change in Britain because they don't want to go through this again.
"You can't avoid by constitution all political ructions," he said. "But you have the ship of state running on a set of rails that make it fairly clear what might happen and what might not happen."
Clerk of the New Zealand Parliament David Wilson said that until the recent case he had not given much thought to whether proroguing Parliament was reviewable in the courts.
His initial view was that proroguing was a proceeding of Parliament because it brought Parliament to an end temporarily.
"But when I thought about it a bit more, I thought it is just an action of the executive. It affects Parliament.
"I don't know that it is breaking new ground or changing the boundaries between the different branches of Government.
"It seems to me squarely within their jurisdiction to declare what the law is and to look at the actions of the Governments on application for a judicial review."
It was just because it involved the highly contentious issue of Brexit that it had got the attention.
Proroguing Parliament in New Zealand stopped between 1993 and 1996. It was decided just to have sessions that lasted three years.
One of the more interesting prorogations in New Zealand was in the summer of 1990 and 1991 when it was used to get the House back faster than usual rather than suspend it.
The first Gulf War had begun when Parliament had already adjourned for the summer.
The Government wanted to recall Parliament to debate New Zealand's contribution but the only way it could be done back then was to prorogue it and set a return time earlier than had already been scheduled.