The Government message to isolate at home at the start of the national Covid-19 Alert Level 4 lockdown was justified, but unlawful, according to a judgement from the High Court.
While the measure was a "necessary, reasonable and proportionate response" to the pandemic at that time, the requirement was not mandated by law and was contrary to the NZ Bill of Rights Act, the court states.
For nine days between March 26 and April 3, the order for people to stay at home and in their bubbles was justified but unlawful, according to the court.
A law change on April 3 then made the lockdown legal. The High Court said its ruling today has no effect on restrictions after April 3, including the current restrictions in the Auckland region.
In his own statement today, Attorney-General David Parker acknowledged the court found an "imperfection" in the initial lockdown orders but says it was "cured by the 3 April order".
He says the finding that the initial lockdown wasn't legally supported and breached the Bill Of Rights Act was for "just nine days".
"In the end the measures taken by the Government worked to eliminate Covid-19, save lives and minimise damage to our economy," he said.
Lawyer Andrew Borrowdale sought a judicial review of the legality of the early stages of the lockdown against the Director-General of Health and the Attorney-General in the High Court in Wellington last month.
In court Mr Borrowdale's lawyer, Tiho Mijatov, said the Government needed to follow the law and couldn't make rules by decree.
"The commonsense notion that the ends don't justify the means, or in this case the emergency, doesn't create the power," he said.
Today's ruling found the initial lockdown enforcement period lasted nine days before it was legally authorised.
Other challenges in the court battle, including around the definition of "essential services", were dismissed.
The court says it's not clear how many charges were laid against people during that illegal period, but says it's likely "that there would be few, if any, prosecutions affected".
Mr Parker says no decisions have been made about whether they'll appeal the decision.