Act leader John Banks did himself few favours this week by pouncing on David Shearer's failure to include details of a New York bank account when he declared his financial interests to Parliament, as required under the MPs' Register of Pecuniary Interests. In calling for the Labour leader to stand down, Mr Banks refocused attention on his own memory lapse over a political donation from Kim Dotcom. Equally, the difference between the two cases was instantly recognisable. Mr Shearer corrected the record off his own bat when he realised his mistake. There was no such candour from Mr Banks.
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.