Nick Smith is one of the Government's more experienced ministers. It is staggering that he saw fit to write in support of a friend's ACC claim when he was the minister in charge of the corporation. His judgment plainly deserted him that day and it deserted him again when the letter - which was sent to medical assessors - came to light this week.
"Ministers still have friends," he said, "and providing there is no inappropriate influence, it is quite appropriate for them to provide information or evidence for medical assessments and other legal processes."
It is not "appropriate" for them to do any such thing when the medical assessments and legal processes involve the agency that must answer to the minister.
Dr Smith, whose expertise is in engineering, not medicine, said his letter was attesting to the woman's state of health before a cycling accident in 2002. In other words, it was a letter any of her friends could have supplied to ACC, but he says she was pressing him to write it.
The woman, Bronwyn Pullar, described as a National Party insider, had sought his assistance for her case many times after he became the ACC Minister in 2008 and he says he had told her it would be inappropriate.
He has not explained why he changed his mind last July and wrote the letter. When he did so, he put his officials in an impossible position. His letter told them it would be inappropriate for him to comment on Ms Pullar's claim but then he went ahead and did so.
It is to the officials' credit that his July letter appears not to have greatly helped her case, because in December she had a meeting with ACC officials at which it was mentioned that Ms Pullar had accidentally received the private data of 6700 other ACC claimants. She denies she threatened to use the privacy breach to advance her claim, as does another "friend", former National Party president Michelle Boag, who attended the December meeting in her support.
The privacy breach was made public last week. Dr Smith, who relinquished the ACC portfolio to Judith Collins after the November election, is not the only member of the Government to face awkward questions. The Prime Minister also knew of Ms Pullar's frustrations with ACC, knew she was pressing his minister for help and his office says he was aware that more than once, Dr Smith had told her it would be inappropriate.
The Prime Minister's office says Mr Key did not know of Dr Smith's supportive letter until this week. The question for Mr Key now is what to do about it. Dr Smith acknowledges his letter was an "error of judgment". He has expressed regrets and given the Prime Minister an apology. Mr Key has accepted it, but he must be left with his confidence in the minister's judgment seriously shaken.
Dr Smith has not had the steadiest hands in the Government. His environmental interests are valuable for the Government but his work on resource management reform and the emissions trading scheme has not been tidy. His weakening of urban tree protection has been repaired by a court.
Under him, ACC turned down too many elective surgery claims that were found on appeal to be justified. With ACC and, now, the local government portfolio, he seems to dive into major reforms too hastily and without sufficient political weight behind him.
The Prime Minister was quick to suspend errant ministers during his first term, one of them for nothing more than charging two bottles of wine to a ministerial credit card.
Dr Smith's lapse of judgment is more serious. It might have been motivated by genuine sympathy, or it might have been a moment of weakness, but it was an improper use of his position.
Mr Key now needs to demonstrate that he does not condone his ministers doing favours for friends.