A legal challenge against the country's level three and four Covid-19 lockdowns is to be heard in the Court of Appeal today.
Former parliamentary counsel and law drafter Andrew Borrowdale is appealing parts of a court judgment from last year.
Borrowdale's lawyer argued in the High Court in Wellington last July that Director-General of Health Ashley Bloomfield went beyond his powers putting the whole country into lockdown.
Borrowdale won one part of the judicial review - that the first nine days of lockdown level 4, 26 March to 3 April, requiring people to stay homewas justified but unlawful.
The court said the lockdown limited the Bill of Rights guarantee of freedom of movement, peaceful assembly and association.
Because public statements by the government and officials stating or implying that people must stay home did not have a formal health order to back them, these limits were not lawfully imposed.
A new order introduced by the government on 3 April corrected that - and the current laws are not affected by the judgment.
What did the court rule against Borrowdale?
Borrowdale's lawyer Tiho Mijatov had argued that three health orders made by Dr Bloomfield on 25 March, 3 and 27 April, putting the entire country into lockdown and defining what was allowed, were unlawful as they exceeded the reach of his emergency powers.
The main argument was about whether the power of the Act to require people to be isolated or quarantined could be used to require the entire country to stay at home in their household bubbles.
Essentially, Borrowdale's lawyer argued the law only allowed on a case-by-case basis to quarantine those suspected of being infected.
Mijatov also argued that Dr Bloomfield giving public servants the power to determine which businesses were "essential", and could therefore continue operating under lockdown, was unlawful.
But the judges ruled against Borrowdale on these two actions.
It said the power could be used to require isolation on a universal basis.
And the High Court said the ability to take decisive action would have been thwarted if the orders had to specify each and every place and premises that must close.
Accidentally leaving one off the list could have serious consequences in the case of a widespread outbreak of the virus.
The court said the ability to define which places must close by listing the exceptions was reasonable and necessary.
It also said that Dr Bloomfield was not in a position to do the fine-grained assessment of which businesses were "essential".
It ruled it was lawful to leave that operational detail to relevant government agencies.
The appeal
Borrowdale is appealing the decision relating to three orders under the Health Act issued by Dr Bloomfield.
RNZ understands this is on the grounds the Director-General of Health did not have the power to enact the lockdown.
Borrowdale said last year the High Court judgment raises vital issues about human rights and constitutional law, which should be assessed by a senior court.
He does not dispute that there should have been a lockdown, but that it should have been done lawfully.
The hearing is set down for two days, and will be heard by Justices French, Cooper and Collins.
Once again the Law Society - which represents 15,000 lawyers - will provide written and oral submissions as a neutral party in the case.
It says the issues raised in the case are of wide public importance, and concern the operation of the rule of law. Its says its perspective sits somewhere between Borrowdale and the Crown, and the Court might find its input useful.
Constitutional and parliamentary law expert Professor Claudia Geiringer said last year the lockdown powers were "some of the most extensive coercive powers ever to be exercised in this country's history".