One of the most fruitful avenues of investigation is to look at material that nobody ever thought would harm them. That’s the kind of material people do not take great pains to hide. Why hide it when it won’t hurt you and there is so much else in the world to worry about?

Trusts set up in the Cook Islands that funnel their money via the Isle of Man and the British Virgin Islands are meant to be hard to find. The same for computer files that are erased – but erased inexpertly.

But in the category of things-we-never-thought-would-matter-much are the dull news releases praising the hiring of a new CFO in 2008, when that person went on to cause the company all kinds of problems the company should easily have been able to foresee. The news release comes off the website, but it’s there on the internet forever in a variety of places: news services that preserve it and the web archive that sucks up web material and keeps it – automatically.

This topic came to mind today after the Wall Street Journal reported that the $6 billion settlement between Visa, MasterCard and millions of the cardholders’ merchants may come undone because of emails (just discovered) that were exchanged between opposing lawyers in the case.

The substance of the emails isn’t the topic of this posting, but rather how the emails were even discovered.

The opposing lawyers were old friends who socialized on the family level. It turns out that one of them was charged with her husband of conspiracy to commit wire fraud against her law firm and her client.

Once that happened, the firm began examining her emails closely and found the exchanges with her opposite and friend.

Her opposite and friend was probably as shocked as everyone else when the lawyer and her husband were charged, but it was too late. Everyday emails (which the article quoted experts and saying were ethically problematic) became headline emails because of events that one of the parties was unable to predict.

It’s a lesson that bears constant repetition: don’t write anything down that would cause you great personal embarrassment if for some reason it ever leaked out. That will cover crimes, ethical violations, and unforeseen circumstances that turn the everyday event into something that is memorable for all the wrong reasons.