Much of the case by applicant Nga Kaitiaki Tuku Ihu Inc focuses on whether the vaccine being rolled out to the majority of the country fits within the provisional consent legislation in the Medicines Act that it has been granted under.
The vaccine, Pfizer-BioNTech Covid 19, has been formally tested on more than 40,000 people - half received the vaccine, the other half a placebo which consisted of slightly salty water. Since it started being used widely, tens of millions of people have now received it.
One of the group's lawyers, Warren Pike, told the hearing that the provisional consent in section 23 (1) of the Act is not meant to encompass a large number of people, and the legislation was designed for "orphan drugs" for a small number of patients.
Pike claimed that it wasn't necessary to have the vaccine being rolled out under provisional consent because it was "self evident" that there is no "need" for the rollout right now because of our Government's success with the lockdown.
However, Judge Rebecca Ellis said there was an ever-present risk of more virulent strains breaking through the borders.
Crown lawyer Kate Wevers said Director-general of Health Dr Ashley Bloomfield was concerned about misinformation being spread about the vaccine and the country was facing a serious threat.
"I don't think there can be any credible suggestion that the court can proceed on any other basis," she said.
Wevers told the court it was not possible to eliminate the risk by only vaccinating border workers - and the borders measures come at a huge economic cost.
She said pausing the programme now would deny people who have only had the first vaccine the full protection, and we don't have evidence on what effect a delayed second dose would have.
As well as this, Wevers said the Crown was concerned that even a short-term interim order could have a chilling effect on vaccine uptake.
Fellow counsel for the applicant, Nelson-based lawyer Sue Grey told the hearing that people would be unable to consent if they didn't know the "risks".
"There's no evidence that they've been given any other alternatives - it's all 'vaccine, vaccine, vaccine'," she said.
Crown lawyer Jessica Gorman noted that the MedSafe website shows the risks associated and had sections for things like what people should know when getting the vaccine.
"It is a serious claim to suggest that people who are receiving vaccine won't get the guidance from a healthcare professional."
Gorman submitted that the total of over 16-year-olds in New Zealand was a limited number of people, therefore abiding by the act.
Documents put forward to court by Nga Kaitiaki Tuku Ihu Inc claim the Medicines Act was breached and it seeks a declaration that the vaccination rollout is unlawful.
It also states that there is a lack of coherent research on the effects or risks of the Pfizer vaccine for use on elderly, immunocompromised, pregnant women, or people using medicines.
The action has been brought against the Minister of Health and the director general of health, as well as Prime Minister Jacinda Ardern, among others.
The judge has reserved her decision.
