Adam Feeley, director of the Serious Fraud Office, let more than his hair down when he invited staff to a celebration of the laying of charges against Bridgecorp director Rod Petricevic. He also let down his position.
He did not quietly invite his team to a drink, which might be normal at the end of a busy week, he issued the invitation by email, announcing they could "celebrate" with champagne "that previously resided in Rod Petricevic's office".
Email is a dangerous medium. It is impossible to control its circulation and it is easily saved for evidence. Worse, there is something about the medium that tempts even cautious people to be clever, ironical and indiscreet.
Mr Feeley is just the latest sender to discover that what seemed entertaining when he pressed the button loses much of its charm in the public domain.
It may be argued whether the greater offence is that he helped himself to Bridgecorp's bubbles in the first place. Mr Feeley has explained that he came by it in his previous position heading the Eden Park Redevelopment Board.
The project used premises previously occupied by Bridgecorp and "three or four bottles of champagne were left behind after the sudden exit of the directors", he says.
The right thing to do would have been to pass the bottle to the company's liquidators, but how many in this situation would have bothered? It is easy to be righteous with the benefit of hindsight. The difference between Mr Feeley and most people is that Mr Feeley was subsequently appointed head of the SFO and he still kept a bottle of Bridgecorp's wine.
He kept it to open, on behalf of the public perhaps, when his office had successfully completed its investigation. "Successful" in this context means the gathering of sufficient evidence to lay criminal charges - a court will decide whether the material is sufficient to find anyone guilty. Mr Feeley will hope the office celebration is ignored when the court weighs everything up.
His judgment was seriously flawed in several respects: knowingly keeping the Bridgecorp bottle, holding a premature celebration of a case yet to begin, and then openly advertising the drinks and provenance of the bottle to a staff which included some who might have to give evidence in the case.
At one level it is understandable that, on a big project, those involved want to relax once a milestone is achieved. Fraud is said to be the hardest category of crime to prove. Intent is necessary and is often hard to establish. Suspects usually have resources and access to a first-class legal defence.
Mr Feeley was appointed to head the office not quite two years ago. He quickly carried out a restructuring under which some of the office's senior staff departed, raising concerns at a loss of institutional knowledge and experience.
But criticism of the SFO's performance had reached a point that the previous Government intended to submerge it in the police. The present Government reversed that decision and put Mr Feeley in charge.
A year ago he had to announce that insufficient evidence of fraud had been found in the Blue Chip group of companies and no charges would be laid. In June he made the same announcement in two other finance company cases. The investigation of Hanover Finance is taking its time.
It is easy to imagine why the office would be relieved at taking a big case to court, but not easy to conceive of a director marking it so inappropriately, with the accused's wine.
The minister in charge, Judith Collins, has referred the incident to the State Services Commission, the referee of public employment. It may not warrant a red card but a serious caution would be in order.