That said, Prime Ministers have previously used their power to dictate MPs' consciences.
Ardern also allowed that removing abortion from the Crimes Act "doesn't mean it wouldn't have regulation that sits around it". Quite what that would be she left unclear.
But her declaration, "I want women who want access to be able to have it as a right" suggests she would leave the decision to the woman concerned.
That's a big change.
Abortion has always been a crime in New Zealand with exceptions. The original exception was if the woman's life was in danger from the pregnancy.
In 1977 the main exception became two certifying doctors agreeing that continuing the pregnancy would result in serious danger to a woman's mental or physical health. That exception applies up to 20 weeks gestation.
Women wanting an abortion have to fib, have to find the right doctors, and have to go through a time-consuming and expensive process.
The divisiveness of the issue has meant no Parliament has been prepared to make the law fit for the purpose to which in practice it is being used.
Removing abortion from the Crimes Act raises curly questions. There's a diverse range of views that Ardern doesn't appear to allow for.
Her "sitting-around" regulation would need to address whether it's abortion on demand no matter how many months and, if not, to determine the limits and circumstances. If there are to be some limits, then abortion under specified circumstances must be unlawful.
The issue then is not the removal from the Crimes Act but rather the regulation. I suspect most people would baulk at abortion on demand for full-term pregnancies.
The detail matters but it's not there. Ardern's announcement was not Labour Party policy.
There's no policy paper backing it. It was a "captain's call". Once again we are being asked to vote without knowing what we are voting for.
