A High Court judge has allowed a son to visit his dying father - overruling the Government's Covid-19 lockdown orders.

Oliver Christiansen's dad lay dying and asking: "Where is my boy? Where is my boy?"

But Christiansen couldn't see him - he was subject to the Government's mandatory 14-day isolation period after arriving in New Zealand on April 23 on a flight from the United Kingdom.

Christiansen spoke to the Herald today about his "eight days of battling and about 36 hours to spare" before his father Anthony Christiansen, who had brain cancer, passed away.

When he left his family in London, Christiansen thought he had time to sit out the quarantine in New Zealand before spending his father's last days with him.

"Things were still looking okay. We thought we had plenty of time to see out the 14 days," he said.

But his father's condition deteriorated rapidly. Doctors gave him only a few days to live and suddenly it was a race against the clock.

Christiansen, who had no symptoms of coronavirus, applied to the Ministry of Health to allow him to see his dying father on compassionate grounds. The ministry, after first mistaking what Christiansen was asking for, repeatedly refused.

An email reply to Christiansen read: "...there is just nothing we can change at this time. 14 days isolation in managed facilities is a mandated requirement in force in New Zealand".

Christiansen then directly emailed Director-General of Health Dr Ashley Bloomfield and the Minister of Health David Clark.

Bloomfield responded within an hour and a half saying he will refer the letter to the managed isolation team to "carefully consider the information". But again he was denied.

Christiansen also asked for a Covid-19 test - but was refused because he had no symptoms.

Today, he said the unwillingness of authorities to test him for Covid-19 was extremely frustrating, as it seemed a "logical step".

So Christiansen went to court to challenge Bloomfield and the ministry's refusal to allow him to cut short his quarantine period.

"It just seemed like continual automatic rejection which fortunately meant the courts were a last avenue for a final roll of the dice," he said.

Meanwhile, his father's health kept going downhill rapidly.

His family was "increasingly desperate" for him to get home so he could farewell his father – and vice versa.

From his quarantine hotel, he could almost see his family's Auckland home just 5–6km away.

The courts recognised how precious time was, he said, and pushed through his case.

At a hearing on Friday in the High Court at Auckland, Justice Tracey Walker said the ministry got it wrong.

She said it was "difficult to envisage more compassionate grounds than those presented here".

Christiansen told the Herald he was able to spend just over a day with his father before he passed away.

When he finally got to see his father, it was an emotional time.

"It was a massive relief to be able to join the family in time," he said.

"There was a lot of emotion, a lot of release – anguish, grief, everything rolled into one.

"It makes you realise, in hindsight, just how critical it is that you're there at that time."

Justice Walker said in her ruling, released today, there was "a very strong argument" to allow Christiansen to visit his dying father after it was "not considered on the correct legal grounds and did not take account of relevant mandatory considerations".

"It had the hallmarks of automatic rejection based on circumscribed criteria rather than a proper exercise of discretion required by the Health Act (Managed Air Arrivals) Order," she said.

The judge said the Ministry of Health's decisions to decline permission were, on their face, "legally flawed on more than [one] basis".

"Had the correct approach been followed, Mr Christiansen's application may have successfully come within the compassionate grounds (with low risk of transmission) or exceptional circumstances categories," Justice Walker said.

The judge said, in her assessment, overall justice "demands an effective and swift response".

"I have in mind here particularly the imminence of Mr Christiansen's father's passing and the very material factor that visitation is only at a private home and not in a public space."

She ordered the ministry to permit Christiansen to leave managed isolation to visit his father.

But he could only do so if he travels unaccompanied by car to his dad's home and remains there until his father dies.

Christiansen was also told to maintain physical separation from other family members at the home and to return on his own within 24-hours of his father's passing in the same car to the isolation facility for the remainder of the 14-day period.

Justice Walker further told him to ensure any necessary cleaning and/or quarantining of that private car is carried out, to wear personal protective equipment, including gloves and a face-mask, to comply with any monitoring requirements by police or officials, and to comply with any other reasonable conditions directed by the Ministry to reduce any risk of transmission.

The judge also considered the question of "the appropriate deference to the expertise of the decision makers in a time of unprecedented public crisis".

"No matter how necessary or demonstrably justified the Covid-19 response, decisions must have a clear and certain basis," she said.

"They must be proportionate to the justified objective of protecting New Zealand bearing in mind the fundamental civil rights at issue – freedom of movement and of assembly in accordance with the New Zealand Bill of Rights Act 1990."

There have been several questions raised about the legality of the Government's strict lockdown orders in response to the pandemic, which have heavily curtailed individual rights and liberties.

Such concerns have included a Crown Law opinion warning the police they had little or no power to enforce the lockdown.

And last Friday, the president of the Court of Appeal, Justice Stephen Kós said challenges over the issue of whether the Government's coronavirus decisions have been lawful should be tested in an expedited judicial review.

Justice Kós made the comment at a hearing over two, ultimately unsuccessful, habeas corpus claims.

In today's full written decision on the case, the Court of Appeal reaffirmed that view and said: "As has been noted by the Regulations Review Committee and two of New Zealand's leading public law academics (Andrew Geddis and Claudia Geiringer), there are unresolved questions about the lawfulness of the notices issued under s70 of the Health Act."

Speaking at her post-Cabinet press conference this afternoon, Prime Minister Jacinda Ardern said authorities needed to make sure "we learn" from the Christiansen and other rulings.

It appeared the response to his application was an automotive response, so it was her expectation the Ministry of Health would take the ruling into consideration.

A total of 283 requests for exemptions to the lockdown have been sought to date - with 24 on the grounds of a relative dying - and 18 have been granted.

Christiansen said he has "full respect" for the New Zealand health authorities and what they are trying to achieve, and is sure "most of the time they are doing a fine job".

"But something seemed terribly wrong with this process," he said.

"If it means that other people don't have to go through the same thing, then it was worth it. And luckily, most importantly, we got to farewell him as a family."