Top executives say a Green Party promise to put together a Cabinet of which half the members are women is misguided, as appointments need to be made on merit.
The Green's co-leader, James Shaw, told the Council of Trade Unions' biennial conference today that he wanted to take a stand against workplace inequality.
Only six of the National government's 20-strong Cabinet are women, which Mr Shaw said was no accident.
"No one seriously thinks that those guys are there because they're the best of the best, or that they've also got so much more merit than any female politicians," he said.
But Prime Minister John Key hit back at the assertion.
"If you're just simply saying that someone is selected as a Cabinet minister because of their gender, then you're doing a disservice to the women who are currently there, by implying that they're there as a token," he said. "We won't have a quota because they imply that the reason women get a job is because they're female."
Labour's Jacinda Ardern was cautious about the idea.
"Our starting point has always been making sure we've got the women who are in the position to move up the ranks. That goes right down to the women who are office holders, and then coming through the ranks into Parliament," she said.
"Once you're in Parliament, then obviously you're reliant on your caucus and your leader enforcing a meritocracy."
NZX figures show only 14 percent of directors in New Zealand are women, while Human Rights Commission data show female chief executives number less than a quarter.
Force not the way - accountants
But the head of Chartered Accountants New Zealand, Kirsten Patterson, said forcing the hand of employers would not fix anything.
"You can't say you've reached equality if you've had to enforce a system for equality to occur," she said.
"We'll only truly get to equality if the systems are changed to the extent that people are appointed on merit across a wide range of characteristics."
The chief executive of the Institute of Directors, Simon Arcus, said quotas were only a cosmetic fix, and unconscious bias wasn't just about gender.
"We need to widen what the issue of diversity actually is - what about your religion, your race, your sexuality, or your age?" he said.
"We aren't malicious about those biases, but we naturally gravitate towards people who are like us."
He said quotas could exacerbate the problem.
"In the world of company directors, I've never met a female senior manager who would be happy being appointed because of their gender - because they believe in their ability," he said.
Remove bias by removing names from CVs
"The way in which change is being adopted overseas is by using intervention points, not by doing training on an unconscious bias, which can actually have a negative effect.
"What employers are asked is whether they're removing candidates' names from CVs when considering their merits. These proactive policies have far more impact and we need to get similarly creative in New Zealand."
Ms Patterson said the problem went beyond the cliche of the old, sexist white man.
"All of us have unconscious bias and in some circumstances, female senior executives show a stronger predetermination towards male candidates," she said. "Areas where organisations make a hard approach and commit to doing work in this space and backing it up with actions are where we think we can make the difference."
But Mr Shaw remained staunch on his plan for equality.
He said Mr Key's assertion that the current Cabinet - which is 70 percent male - was appointed by merit showed the Prime Minister doesn't believe women have as much merit as men.
The Council of Trade Unions has backed the quota and said the Greens were leading the way by guaranteeing equal representation.