It pains me to admit this, but Kurt Greenbaum was right.
Greenbaum, director of social media for the St Louis Post-Dispatch, posted an article detailing his efforts to protect readers of the paper's website from profanity. In short, after noting that one offender was posting from a school, Greenbaum called the school and informed them of the times and IP address of the naughty postings. In short order, the school employee was confronted by the school and quickly resigned.
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So Greenbaum had the authority to act as he did, but was it the right action? One comment--sadly I've lost the cite--complained that Greenbaum's was "a dick move". Again, I am forced to come to Greenbaum's defense. A dick move is spilling a drink on your date in order to get their clothes off, or faking a coughing fit during a competitor's presentation. It presumes prior knowledge that the action is unethical.
Greenbaum's was a bumpkin move. He allows after the fact that he might have "walked the idea around the newsroom" but what good would asking equally clueless people have done? For all the firing the Post-Dispatch has done over the last few years, I'm certain the legal team remains strong and robust. That would be a place to start, and could provide information necessary to defend your actions on legal grounds.
He further claims that an IP ban was considered but declined as extreme, as it would ban the entire school from the site. If such a ban is non-reversible, this is a fair argument, but the temp-ban is a tool well loved by moderators. A 30 minute ban would solve the problem with a minimum of inconvenience.
These are but two possible approaches to the problem, and apparently neither was considered. Why? Because as Greenbaum admits in the followup, calling the school was "easy". Just as it was easy for Amazon to delete purchased books from Kindle users' inventories, or for a cop to Tase a 10 year old, his problem was easily solved by contacting the school and violating the poster's admittedly erroneous expectation of privacy.
As is often the case, the easy solution won out over the responsibilities of ethics and authority.