A Government ministry says a second "wife" in a polygamous marriage may be entitled to a sole-parent benefit.
The surprising statement by the Ministry of Social Development has been condemned by lobby group Family First, and is disputed on legal grounds by welfare law expert Mamari Stephens.
Family First director Bob McCoskrie says the law needs to be clarified to provide a consistent ban on polygamy.
He asked the ministry for the legal position after the recent case of Pakistani-born meat wholesaler Yasir Mohib, who was jailed for a year for beating one of his wives with a hammer because she complained that he was holding hands with his other wife.
The ministry's general manager of ministerial and executive services Elisabeth Brunt replied that the Social Security Act referred to only "any 2 people who have entered into a relationship in the nature of marriage".
"The ministry is only able to treat one woman as being married to a man at any one time," she wrote.
"Multiple marriages are not recognised under the Social Security Act and should such a circumstance arise where a person applied for a benefit with multiple 'wives', the ministry would only be able to treat one wife as being married to the man."
"As such the other 'wives' would be regarded for benefit purposes as being either single or sole parents, depending on their individual circumstances.
"They may be able to receive a benefit in their own right depending on their individual circumstances. Each situation would be assessed on a case by case basis."
However Stephens said a "second wife" in a polygamous relationship could not get a sole parent benefit because a sole parent is someone "who is living apart from, and has lost the support of or is being inadequately maintained by, the person's spouse or partner".
"You are not going to be eligible for a benefit if you are getting emotionally and financially supported by someone else," she said.
Stephens said it was a crime in New Zealand law, bigamy, if anyone who is already married to one person "goes through a form of marriage or civil union in New Zealand with a third person".
But she said there was no law against living in de facto relationships with any number of people, and there was also no ban on having several legally married wives if the marriages took place overseas before the parties became New Zealand residents.
In fact the Family Proceedings Act of 1980 states that the term "marriage" "includes a union in the nature of marriage that (a) is entered into outside New Zealand, and (b) is at any time polygamous, where the law of the country in which each of the parties is domiciled at the time of the union then permits polygamy".
McCoskrie said the law was clearly inconsistent.
"I want consistency," he said.
"Is polygamy being recognised covertly by the Government? That is the first concern.
"Secondly, if the Government is going to come down on welfare fraud, then we need to have clarity and consistency around the rules, not turn a blind eye to certain arrangements."
He pointed to Canadian Court findings that women in polygamous relationships were at higher risk of physical and emotional harm, and their children were at more risk of abuse and neglect.