Labour's gender rule will ensure that 45 per cent of its MPs will be women after the next election, reaching 50 per cent by 2017.
This is a far more sensible arrangement than the previously proposed "man ban", which would have permitted women-only contests for the party's ticket in electorate seats.
The push for guaranteed gender equality has now produced an approach that will satisfy most in the party, even if many in the wider community will see it as verging on political correctness.
Labour sought to leaven that prospect by noting it already had 41 per cent women in its caucus. It would not, therefore, take much to hit next year's target.
Maybe not, but that makes light of the fact that most of the new candidates likely to get high places on the party list or selection for safe electorate seats will have to be women.
Indeed, if Labour were to win 41 seats next year, as suggested by current polling, 19 of its MPs would have to be female, leaving only two of the seven new seats for men.
And that may not be the most challenging aspect of it. The conundrums will mount if Labour appears likely to lose MPs at an election.
The only way to get a substantial intake of new male MPs next year will entail either dumping some sitting male list MPs down to unwinnable places on the list, or pushing electorate MPs to retire from politics to open up more seats.
The finger is, therefore, being pointed at senior Labour figures such as Phil Goff and Trevor Mallard.
Both have indicated they plan to stand again. Indeed, Ross Robertson is the only Labour MP to have so far announced he will leave Parliament next year.
The contrast with their opponent is obvious. It seems National MPs are prepared to retire when they see they have gone as far in politics as they can.
Some may leave with regrets; others will be happy to go. The vast majority, however, seem prepared to go back to the enterprise or profession of their pre-parliamentary days.
Could it be that Labour MPs have tended to regard politics as more of a lifelong career? In the process, they have made their party's renewal more difficult.
The Labour leader, David Cunliffe, says adopting a quota for women is all about "moving towards normality".
Philosophically, the party believes it is important to put this stake in the ground.
Practically, there may yet be some benefit in the immediate future from the added pressure to renew itself.