These days, courts are increasingly asked to apply traditional legal rules, which were developed years, if not centuries ago, to scenarios no one could have envisioned back then.

A recent case from New York illustrates the point. The facts are kind of sad really. A woman worked for a law firm. As part of her job, she had access to e-mails sent along the firm’s computer server. As it turns out, she discovered a number of e-mail messages one of the firm’s lawyers sent to his wife questioning the woman’s postpartum depression and care of her infant.

The woman turned the e-mails over to her supervisor, who apparently was much more upset with the woman’s snooping than he was the content of the e-mails. The firm fired the woman.

Perhaps not surprisingly, the woman filed a lawsuit against the lawyer and his wife for defamation. She claimed the content of e-mails was false and damaged her reputation.

The woman’s case however, failed because she couldn’t prove that the statements were ever “published.” “Publication” doesn’t mean anything fancy. It just means the defamation defendant has to actually make the disparaging statement to someone else. If I write horrible, untrue things about someone in my private diary, that person can’t sue me for defamation. If I show my diary to just one person, he can.

So, why couldn’t the woman sue the lawyer for defamation? According to her complaint, he wrote false disparaging things about her and shared that with at least one other person – his wife. Sounds like publication, doesn’t it?

It does, except for something called “spousal privilege.” The privilege means that spouses are allowed to communicate freely with one another. So what a husband tells his wife can’t be used against him (unless he says a dress makes her look fat, but that is for another newsletter). Of course, the privilege only covers private communications – if third parties are part of the discussion, there’s no privilege.

The woman argued the privilege didn’t apply because the lawyer sent the e-mail over the firm’s computer system, and since third parties had access, the privilege was lost. The court was unimpressed. Despite the potential third party access, the lawyer and his wife had a “reasonable expectation of privacy” in the communications. And the court noted that no New York statute or court opinion had ever found an exception for e-mail messages.

The legal lesson here is that e-mail communications don’t lose their private nature because third parties might be able to access them. The practical lesson is – don’t assume that your “private” e-mails are all that private.