UPDATED 3.15PM:  John Key doesn't buy the Greens' argument that 50 percent of Cabinet should be women.

LISTEN ABOVE: James Shaw, Green party co leader talks with Larry Williams on Green's proposition for parliament.

The Greens have said half of its nominations for Cabinet will be women if it's part of the next Government.

The Prime Minister said gender quotas do little for women.

"They imply that the reason they get a job is because they're a female - actually the women that we've had have led our country, led our judiciary, led our biggest companies, have been Governor Generals of New Zealand have been better, or as good as any man that could have done that job."

But the Trade Unions Women's Council feels very different about the matter.

They said the Green Party's promise of a 50/50 gender split of Parliamentarians is a positive and exciting move.

The Council of Trade Unions Women's Council spokesperson Sheryl Cadman has an answer for those who say the appointments should be based on merit not gender.

"We would say that that will still be the case. It will just be that those people based on merit are women, rather than men."

Sheryl Cadman said 70 percent of Parliamentarians are men, which hasn't changed for the last ten years.

The Green Party insists better gender equality is needed - and change has to start from the top.

A similar idea from Labour faced a backlash and was labelled "the Man Ban", but Green co-leader James Shaw isn't worried.

The policy wouldn't be about men, but women, and the action was needed because women aren't currently fairly represented, Shaw said.

"A cabinet that was fifty percent male and fifty percent female would probably look on some of those issues a bit differently from one that's heavily dominated by men."

"We think it is one of things that you need to do in order to start the ball rolling."