Any decision on delaying the General Election should be based on safety-to-vote considerations and not on any perceived unfairness by a political party, law professor Andrew Geddis says.
With Covid-19 back in the community, Labour Party leader Jacinda Ardern is under pressure from National to change the election date.
National Party leader Judith Collins is calling for the election to be pushed back either to November or early next year. With campaigning on ice due to Covid-19 restrictions, National and other parties say it wouldn't be a fair race.
In response, Green Party co-leader James Shaw has criticised National for the move, saying it is out of concern for their own self-interest, not democracy. Labour's Grant Robertson also called some of National's claims about what the government knew about new Covid-19 cases "nonsense".
University of Otago law professor Andrew Geddis, says there are also complex constitutional matters to consider for an election date to be changed.
"The way that the election day is legally specified is through something called the election writ, and so once the Governor-General issues that writ, then that is the legal instruction to have an election on that day.
"That writ was not due to be issued until Sunday the 16th, so up until that writ's been issued it's entirely open to Jacinda Ardern as the Prime Minister to say to the Governor-General 'have the election on a different day'.
"That is entirely her prerogative, it's in her hands - she can make that call."
Once the writ is issued, responsibility moves to the Chief Electoral Officer, he says.
"At that point in time the responsibility for delaying, if Covid gets worse and it can't be safely held, is the statutory power that lies with the Chief Electoral Officer.
"So, it then goes over to the election officials to delay the election if necessary once it's been put in place through the writ."
Once Parliament is dissolved a writ to hold an election must be issued within a week, Geddis says.
"Parliament has not yet been dissolved, it was meant to be dissolved on Tuesday but that didn't happen because of Covid. So, up until Parliament is dissolved there's no need to issue an election writ at all, that can extend out for as long as parliament is still in session."
However, time is running out for issuing a writ for the planned 19 September election, he says.
"When you get into early next week, if you still want to have the election on September 19th as is planned at the moment, you really need to make the call by then because of all the mechanics that are necessary.
"You still don't have formal candidates nominated, that doesn't happen until the writ has been dropped."
He says if it is decided next week to delay and nominate a new election date, that remains within Ardern's power.
"If they decide that they have to delay it, there'll be an announcement made very early next week to say 'we just don't think the election can be safely held on the 19th September, so here is the new date that we're going to work towards'.
"What that new date will be is entirely in the Prime Minister's hands right up to the end of November. She can choose any Saturday - it has to be a Saturday, the law says it must be a Saturday - and say this will be the new election date and then she advises the Governor-General of that and the Governor-General will issue the writ to then make that the official election date."
The problem then is that the Covid situation may not have improved or may have worsened, he says, and determining whether an election can be held safely lies with the Electoral Commission.
The Commission has been planning for this election with possible Covid restrictions front of mind.
"It has planned to hold the election on September 19 under level 2 conditions, as they did their planning for the election this year, they have gone out and said how can we hold this election if we were under level 2? And they say it can be done.
"They also say they can hold the election on September 19 if there are up to 5000 people across the country living under level 3 conditions."
If that is not the case, and it is deemed unsafe, the Chief Electoral Officer can extend by three days under her own powers and then for periods of a week after talking with the Prime Minister and Leader of the Opposition, he says.
He says the Prime Minister will be taking advice on what the levels of restriction the country is likely to be under on 19 September.
"If the advice is that Auckland is going to be under level 3 lockdown in September, therefore an election can't be safely held, they will have to put the election date back."
But this process cannot go on forever, Prof Geddis says.
"At some point there's just going to have to be a call made … 'this is going to be the day we hold it', and we cross our fingers and hope to whatever higher power you want that it's actually possible given the Covid situation.
"If it turns out it isn't, well then the onus is on the Chief Electoral Officer to take those steps authorised under the Electoral Act to delay the election and use alternative means of voting to try to deliver a safe election.
"It's the best we can do in a really imperfect world."
A situation could arise where early votes are in and the election day itself is then delayed, he says.
"It is possible to suspend voting in some places and allow voting to take place in others. If that was to happen however, the count of any ballots is withheld until everybody gets a chance to vote
"So, it may be that some people are voting in some places and those votes are just kept until everyone else has had a chance to vote.
"And only once everyone's votes are in are those ballots then counted and announced."
The constitutional time frames are tight, he says.
"This is the third year of Parliament's term, so Parliament must expire by early October under law.
"Once Parliament's expired you have to have an election within a certain number of days of parliament expiring.
"So, you could actually under law drag it out until the start of December, but in practice November 21 is the last day you can have an election and have it all tidied up and finished before Christmas."
Parliament must reconvene for an election to happen next year, he says.
"We have to have an election this year unless Parliament meets and three quarters of MPs agree to extend the parliamentary term.
"That hasn't happened since World War I, we've had elections throughout the depression, we've had elections through World War II, we've had elections through all the other trouble and strife in New Zealand on a three-yearly basis.
"If this is considered to be such a terrible and unavoidable catastrophe and we need longer, it is possible - but it would be constitutionally a huge move to take."
Political fairness takes a back seat to public safety, he says.
"The primary question has to be whether the election can be held safely or not and that shouldn't be a political decision.
"That should be what are the public health officials saying about the estimated tracking of the disease and the likelihood of being in lockdown in various places.
"Beyond that you start getting into questions of political advantage and political fairness and so on and the problem there is there is no such thing as a completely fair and completely objective election."
Politically there are advantages to the National Party if the election is delayed and to Labour if it goes ahead as planned, but he says this is not the point.
"For me the decision should be purely and only focussed on when it is safe to vote, and I'd like to keep the politicians as far away from that as possible."