Right To Life New Zealand filed suit against the Abortion Supervisory Committee saying the agency has misinterpreted the law.
The measure was approved "with the objectives of stopping abortion on demand and to provide effective legal protection for unborn children," the group previously told LifeNews.com.
However, the pro-life group said that nation's government since 1978 have failed to correctly apply the act.
The group, which also sued the country's attorney general, said 98 percent of abortions have been approved for mental health reasons, even though studies show abortion has a negative impact on a woman's physical and emotional health.
Justice Simon Franc rejected a request from the committee to dismiss the lawsuit.
The judge said Right to Life's claim included questioning the definition of when the law deemed someone to be alive and thus had human rights under the New Zealand Bill of Rights.
According to the Press newspaper, he pointed to common law on the island nation called the "born alive" principle whereby unborn children have no legal rights until after birth.
"Right to Life sees the `born alive' rule to be a potential impediment to its case and wants to be in a position to contest that rule if either committee or the court see it as relevant," he said, according to the newspaper.
In previous comments to LifeNews.com, the pro-life group expanded on its position.
"It is our belief that these abortions are for socioeconomic reasons masquerading as psychiatric," the group said.
"Evidence will be given by Right To Life that the committee has failed to hold certifying consultants accountable for the lawfulness of their authorizations for abortion."
The Abortion Supervisory Committee released its annual report to the nation's parliament last October on the number of abortions there and indicated that abortions were down in 2005 to 17,531 compared with 18,211 in 2004.
The 2004 number was down from the 2003 high of 18,511 abortions.