A group fighting the fluoridation of drinking water supplies in the south Taranaki towns of Waverley and Patea has taken its legal battle to the Supreme Court.
It follows earlier hearings in the High Court and Court of Appeal, which ruled against legal arguments raised by New Health New Zealand, including a suggestion that fluoridation of the water breached the right to refuse medical treatment.
New Health's lawyer, Mary Scholtens QC, told the Supreme Court today the jury was still out on whether the substances used to fluoride drinking water were safe and effective.
The Court of Appeal and High Court had ruled that those compounds were not medicines.
But Ms Scholtens said they were also not the same chemicals as the medicine-grade substances used in fluoride tablets.
She said the fluoride put in water supplies contained by-products of superphosphate production and could contain mercury, arsenic and lead.
Ms Scholtens said the Bill of Rights guaranteed a right not to undergo medical treatment and the group she represented believed fluoride qualifies as a medical treatment.
She said when the Court of Appeal considered that matter, it took a narrow reading of the Bill of Rights which was incorrect.
"The section 11 right must be looked at, not primarily from the state's perspective but from that of the individual.
"It says everyone has the right to refuse medical treatment, but it [anticipates] that people would be treated against their will only when it's needed to protect the health of other people."
Ms Scholtens said that could not include the provision of fluoride in drinking water.
The Court discussed other instances in which additives are put in products consumed by the community, such as iodine in salt.
However Ms Scholtens said the fluoridation of a water supply was not the same as adding folate to bread, and the latter would not breach people's rights to not be medicated.
"In terms of salt, or folic acid or any of those other things ... we have a choice; iodised, not iodised, folic, not folic - it doesn't matter.
"[But] we have findings of fact from the High Court and Court of Appeal that there is no realistic option for people to avoid fluoridated water ... it's used in so many things it's harder to avoid."
Ms Scholtens said New Zealand's drinking water legislation included the power for chlorine to be added to make the water pure, but did not add anything about the addition of something like fluoride.
She said drinking water was the method by which the fluoride would be delivered to the community, but there was nothing in the Local Government legislation authorising a council to do that.
Ms Scholtens said her clients believed it was up to the Crown or local council to show that use of fluoride in an area's water supply was a proportionate response to dental health issues.
The case is expected to run until Friday.