In September 2012, Facebook posted that it had reached the one billion user mark. One in every seven people on the planet, Facebook beamed, has a Facebook account. Well, actually, Facebook only knows how many accounts it has, not how many people use it. Anthony Weiner, for example, probably had two accounts, one in his own name and one in the name of Carlos Danger.

A billion, a schmillion, whatever. Face­book has a lot of users — every one of them a potential gunshot to their own foot.

Take Toby Sutton, hired as a professor of funeral science, who, for reasons that must have seemed funny to him at the time, posted to Facebook, "Toby Sutton hopes this teaching gig works out. Guess I shouldn't have cheated through mortuary school and faked people out."

Toby, you're a riot. Oh, and Toby, you're fired. His termination was affirmed by the U.S. Court of Appeals for the Eighth Circuit in 2012.

Take Franklin Jeffries, embroiled in a visitation dispute, who thought he would express his thoughts in a music video he posted to his Facebook account with the catchy lyrics: " 'Cause if I have to kill a judge or a lawyer or a woman I don't care. 'Cause this is my daughter we're talking about."

Franklin, what a kidder you are. Hilarious! Oh, and you're guilty of transmitting a threat to injure a person in interstate commerce, under federal law. Go directly to jail. Do not pass Go. His conviction was affirmed by the Sixth Circuit in 2012.

Or take Chelsea Chaney. Chelsea, it seems, had her picture taken, when she was a 17-year-old high school senior, standing next to a life-sized cardboard cut-out of Snoop Dogg (now Snoop Lion) as he held a can of the 12-percent alcohol drink Blast. Chelsea herself was clad in an itsy bitsy teeny weeny bikini that showed off her navel piercing and bling. Chelsea was proud enough of the picture that she posted it to her Facebook account.

Now Facebook does not allow minors to make their accounts available to the entire public. The least restrictive privacy setting a minor can select is "friends plus friends of friends." So that's how Chelsea "protected" her picture.

TYPICAL OLD MAN

The typical old man who writes columns for The National Law Journal has 39 Facebook friends, so let's assume that a hip, attractive high school senior has at least a hundred friends, and every one of her friends has 50 different friends. So Chelsea knew or could easily have figured out that she was sharing her Snoop Dogg, Blast-bling moment with 5,000 people, give or take.

And one of the people she shared with, who apparently was a friend of one of Chelsea's friends, happened to be an administrator at her high school who downloaded the photo for a seminar he was putting on for a couple hundred people as an example of "be careful what you post."

He was trying to make the point that maybe, just maybe, Chelsea, and others like her, might not want pictures like these available online. Forever. It might be embarrassing.

HOW EMBARRASSING

Exactly! Chelsea was outraged to have her embarrassing photo shared with 200 people! Her parents were outraged! Her lawyer was especially outraged! Chelsea filed suit in the Northern District of Georgia against the school district, seeking $2 million in damages for intentional infliction of emotional distress.

Did I say Chelsea was outraged? What she actually said, on camera, was, "I was embarrassed. I was horrified." At the same time, however, she gave express permission to the news media to republish the same picture as she explained her horror. Whether permission was needed is a fair question, given that Chelsea had already posted the photo in a way that probably allowed 5,000 or so people to see it, copy it, download it and transmit it, but she gave permission for the media to use the photo and, boy, did they ever.

Google the phrase, "Chelsea Chaney Facebook Lawsuit," and you will get about 70,000 hits, most of them with copies of the photo or videos that imbed the photo or links to the photo. Fox News, USA Today, Huffington Post and ABC News, among many others, posted the picture. The ABA Journal did not post it, but there is an easy link that makes the photo a finger press away.

I'll take Chelsea at her word that she was embarrassed to have the school district share the photo with 200 people in nonelectronic form. But I am trying to sort out the right adjective to describe how she must now feel about her own re-publication to, well, pretty much the world, or at least to the 2 billion or so people who have access to the Internet.

Now, here's where it gets interesting. The school district has filed a motion to dismiss, predictably opposed by Chelsea. But if I were her future self, I would think twice about wishing that her lawsuit survives the motion and goes to discovery.

Maybe the Dogg photo was the only post ever that seemed like a good idea at the time and not so much now. But every personal post Chelsea has ever made may become fair game in discovery. Even if Chelsea had selected the highest possible level of Facebook privacy for her posts, post them she did. And if a litigant can demonstrate potential ­relevance, those posts become discoverable.

In Giacchetto v. Patchogue-Medford Union Free School Dist., a federal court in the Eastern District of New York earlier this year ordered a dive into the plaintiff's privacy-protected Facebook account, noting that "in seeking emotional distress damages, Plaintiff has opened the door to discovery."

ALTERNATE STRESS FACTORS

The court cautioned that unfettered access would not be allowed, but anything related to alternate stress factors was clearly relevant. Likewise, a federal court in Colorado this year ordered disclosure of plaintiff's "entire Facebook activity" because it may be relevant to his claims of emotional distress and physical injury.

In Chelsea's lawsuit, a case could be made that the defense is entitled to other possibly embarrassing photos as well as any message traffic that shows how Chelsea took it when a friend "liked" such a photo. Was she really embarrassed by pictures like these, or proud? Of course, Chelsea's Facebook account is likely very different now than it was then. She likely has changed her privacy settings. She likely has taken down posts of other possibly compromising pictures and chats.

But if so, she will have that whole spoliation thing to deal with. Have fun in discovery, Chelsea.

YES, YOU CAN MAKE THIS STUFF UP

The admissibility of evidence found on the Internet and Facebook in particular presents unique authentication issues for the very reason that anyone can pretty much post anything they like. And friends or strangers can create total fictions.

Fraudulent Facebook postings are so common that there is a term for it: Status-tory Frape. It happens when someone hacks your account, you use a public terminal and forget to log out, or when someone merely creates an account using your name.

Ask Manti Te'o, the University of Notre Dame linebacker who fell in love with a woman who turned out not to be a woman but a man, or Diane O'Meara, the actual woman whose photo was used without her knowledge to create a false Facebook account to sell the hoax to Te'o.

But put aside fraud and pranks. Consider what we voluntarily do to ourselves.

Chelsea merely embarrassed herself, or so she said. Toby got fired; Franklin got jailed. And there are legions of similar stories.

In U.S. v. Morris, which went to the Fourth Circuit, Dennis Morris had his parole revoked in part because he posted a picture of himself holding a firearm. In Jaszczyszyn v. Advantage Health, which went to the Sixth Circuit, Sara Jaszczyszyn was fired when, while she was on disability leave, she posted pictures of herself reveling at a local beer festival.

So here is my advice. Don't post anything to your Facebook account unless your mother has approved it first. Of course, that wouldn't have worked for Chelsea. Her mother's friend took the picture. But it would probably work for the other billion of us.

Robert L. Byman is treasurer of the American College of Trial Lawyers and a litigation partner at Jenner & Block in Chicago. He represents clients in complex commercial cases on issues ranging from patents and intellectual property to civil rights. He can be reached at rbyman@jenner.com.