A High Court judge has found a law that prohibits all prisoners from voting breaches their human rights.
The ruling is a victory for career criminal Arthur Taylor, who has been fighting to give prisoners the right to vote since a 2010 law took it away from all inmates, no matter how long their sentence.
At the time the legislation was being considered, the Attorney-General warned Parliament that a blanket ban contravened the Bill of Rights, but the law was passed anyway.
Now Justice Heath has made a formal declaration that the law is inconsistent with the Bill of Rights and is unjustified.
Under New Zealand law, Parliament can pass legislation that is inconsistent with the Bill of Rights if there are justifiable grounds for doing so.
However, Justice Heath found that the law was full of inconsistencies and would lead to arbitrary outcomes.
One example he gave was home detention, where the person would keep their right to vote, whereas a person sentenced to the same amount of time in prison would be disenfranchised.
Voting was one of the most fundamental aspects of a democracy, Justice Heath said.
"The purpose of a formal declaration is to draw to the attention of the New Zealand public that Parliament has enacted legislation inconsistent with a fundamental right."
In a recorded statement sent to Radio New Zealand, Arthur Taylor said he was "rapt" with the court ruling.
"His Honour Justice Heath's very courageous decision strikes a strong blow for the rule of law, not only for prisoners, but all other New Zealanders, in upholding their fundamental rights against even the Parliament," he said.
Decision a moral signal
A professor of law at Otago University, Andrew Geddis, said Parliament was not legally obliged to reconsider the legislation.
However, the declaration was a strong moral signal to do so, he said.
"It's the first time that the court has used the Bill of Rights Act to send a direct message back to Parliament, to say ... that a law that Parliament has passed is just unjustified.
"It's a bad law, so even though it still exists and has to be applied, it's not a good one," Mr Geddis said.
An earlier High Court judgment had already criticised the law as "constitutionally objectionable".
Justice Ellis ruled last year that she could not overturn the ban because it had been lawfully passed by Parliament.
But she used her court judgment to spell out in detail the various criticisms of the law, and wrote that Taylor was "not some vexatious voice in the wilderness" on the issue.
"I think it is important to record that there is considerable, and considered, support for the position he is advancing."
The Greens and Labour were among those calling last night for the ban to be reconsidered.
A spokesperson for Justice Minister Amy Adams, said the minister was still considering the judgment.
"But it's worth noting that, as the judge has stated, the finding that a piece of legislation breached the Bill of Rights Act does not invalidate the legislation."