Nevertheless, the incident, viewed in isolation, was a blow to Mr Shearer's credibility. At best, he could be accused of untidiness. At worst, informing Inland Revenue about the American account, which contains payments from his time with the United Nations, yet somehow forgetting his obligations to Parliament, suggested an inattention to detail unworthy of an aspiring Prime Minister.
Mr Shearer was also shown to have failed to adhere to the highest of standards after demanding that very thing from others. Inevitably, the episode invited accusations of hypocrisy such as that levelled by Mr Banks.
If Mr Shearer wants an extreme example of how potentially damaging that can be, he need only refer to the case of one of the Act leader's predecessors, perk-buster Rodney Hide. The incident also undermined his ability to criticise memory lapses by others, not least John Key. What we forget we do, indeed, we often come to regret.
David Shearer's credibility is in tatters. It is simply beyond belief that he would declare the existence of his US account to IRD, but forget that he had it when filling out his pecuniary interest return to Parliament, his employer.
When this story first broke, we were inclined to give Mr Shearer the benefit of the doubt. We are no longer so sure about that. David Shearer needs to stand aside as leader of the Labour Party.