Ardern will not escape questioning about it. But she will not be sullied by association, nor will anyone expect her to go out of her way to defend NZ First.
Peters has taken issue with the timing of the announcement of the charges so close to the election, claiming it shows bias and is unfair to his party.
But the timing could not be better for Ardern.
Her current coalition is effectively over. The campaign period means she will not have to consider what to do about her coalition partner.
She can simply leave that to the voters.
One of the differences between 2008 and 2020 is that Ardern is at the end of a first term whereas in 2008, Labour was at the end of a third term and facing a strong challenge from National under John Key.
If Labour was to have any hope of getting back in, it would have needed NZ First.
It is now looking highly unlikely Ardern will need NZ First to form a new government. Even before the news of the SFO charges, it was also looking likely there would be no NZ First anyway.
Nor has Peters given her any reason to defend NZ First out of good will. He has increasingly attacked Labour in a bid to boost his own chances.
His jibe that the 2017-20 Labour Government was the most challenging he had to deal with because of the lack of experience in it, was intended to highlight his experience compared to most of the Labour ministers.
But it also had the effect of portraying Ardern as out of her depth.
Ardern laughed it off at the time but such comments are not easily forgotten.
And Ardern has shown she is not above getting a bit of revenge when she has a mind to do so.
She has left the usual argy-bargy of attacking National to her henchman, Grant Robertson.
But this week she got in there herself.
The trouble with proclaiming from the mountain tops that you want a clean campaign, full of facts and empty of personal attacks and exaggerations is that it gives you very little room for erring from that path.
So it did not take long for National to accuse Ardern of "dirty politics" this week after she took a leaf out of Judith Collins' book.
That came when Ardern was asked for her response to the National Party's policy announcement to double the funding for the Serious Fraud Office.
She observed it was an interesting policy, given Collins' history with the SFO: "as a previous minister, her engagement with the SFO led to her job loss".
It was a reference to allegations in 2014 that Collins had tried to undermine former SFO head Adam Feeley, using her links to blogger Cameron Slater to do so.
Collins had to resign but an inquiry later found no evidence of wrongdoing, and Collins was reinstated as a minister after that year's election.
It was a very rare excursion into dirt-flicking by Ardern. Elections are fought on trust, and Labour has expended significant energy trying to dent voters' trust in National's economic management.
That has had some effect, according to the latest NZ Herald Kantar poll, which showed more people still trusted National when it came to the economic recovery but only by 43 per cent to 39 per cent for Labour.
Now it was clearly the time to try to dent trust in National's leader as well.
Ardern was clearly aiming to remind voters of the Collins of old, the Collins who was not trusted by Sir John Key.
Collins, like Peters, is very sensitive to being wrongfully accused or claims of wrongdoing she believes are unjustified.
So Collins took issue with it, demanding on her media interviews the next day that Ardern retract her dig.
Her reaction was understandable – but perhaps also foolish.
The result was that it simply dragged the issue up the headlines and on for another day – reminding people more about the years Collins surely hopes have faded in voters' memories.
It was also perhaps Ardern deciding to dispense Collins a taste of her own medicine.
After the first leaders' debate, a triumphant Collins had scoffed at Ardern's comment that she did not think debates should be "blood sports."
"Poor wee thing," Collins had said.
Ardern could well now say the same thing back.
