You're anonymous when you post comments online—except when you're not. Though many Internet users still believe that their identities are as hidden as they choose to make them, online anonymity is not always guaranteed and, in fact, there's no way to stay truly anonymous. There is always a company somewhere that has information that can be traced back to you, whether it's Google or your ISP, and judges have shown themselves willing to issue subpoenas to unmask anonymous posters.

But what determines whether or not you will be unmasked? Unfortunately, it's hard to say—there is no black-and-white line to be crossed. There is, however, a gray area that you could find yourself in if you do the wrong things.

Really piss people off

The first step to getting yourself unmasked online is obvious enough: give someone a reason to go after you by being as obnoxious and offensive as possible in a series of online comments, whether on your own blog or on a forum, or everywhere in between. Of course, being offensive isn't against the law, and is actually protected by the First Amendment as free speech. However, the more attention you draw to yourself in this manner, the more likely it is that someone you're targeting will attempt to sue you.

It's what you do next that could determine whether you are walking directly into the gray zone or not.

Fail to file an objection

"The civil system is set up by default to allow for the disclosure of information," Electronic Frontier Foundation staff attorney Matt Zimmerman told Ars. "By default, unless someone objects to a specific request for info, someone's identity is most likely to be disclosed."

In a civil lawsuit, a litigant is often allowed to send out subpoenas in the name of the court—without the court's prior approval—to Google, Yahoo, or wherever in order to request information about someone, Zimmerman explained. This can even be done before filing a lawsuit in some states, and some entities use it as a way to find out who their detractors are without ever drawing up a complaint. If the accused user doesn't file an objection within some period of time (Google's is 20 days), the company will usually go ahead and turn that information over.

One of the highest profile examples of this is a recent case that pitted a former Vogue model against an anonymous blogger posting on a site called "Skanks of NYC." The blogger made numerous posts about the model in question, which the model (Liskula Cohen) argued were defamation—she alleged that she was decidedly not a skank and that the statements were meant to ruin her reputation.

In August, the court agreed that the posts could be found by a jury as defamatory and gave the green light to subpoena Google for the identity of the blogger, Rosemary Port. Port turned out to be a loose acquaintance of Cohen's who had been to various parties with the model around NYC and apparently had an axe to grind. Since then, this case has become even more controversial, as Port has talked about suing Google for compromising her privacy and otherwise ruining her life. Zimmerman didn't seem to believe she would have a case, though. "If that blogger wanted to appeal the decision to subpoena her identity, she could have," he said. "I don't know why she didn't."

Of course, the onus isn't entirely on the person being sued if they fail to respond to the subpoena. Zimmerman noted that many service providers (Google included) will send a notification to the user's e-mail address, only for it to end up in a spam folder or not get noticed for weeks. And often, the person receiving the notice don't know what to do and doesn't have the resources to object, leaving them stuck with no response at all. Zimmerman said that it's not surprising that the threat of a lawsuit or being outed might chill speech for those who don't have the legal know-how to oppose these subpoenas.

Seriously: make 'em work

If you do file the objection, the court will be forced to ask whether the complaint alleges something that is actionable and whether the information is absolutely necessary for the case. Luckily for you, the courts have often sided with anonymous posters in these cases, such as a case involving anonymous donut shop critics, a blogger critical of a local police department, and a blog commenter who targeted a Massachusetts real estate developer. In these situations, the judge felt that these commenters were acting within their free speech rights, and the ultimate decision was that the commenters were protected by the First Amendment.

Another judge in California recently acknowledged that there may be some scenario in which unmasking commenters is OK, but that the litigant would have to jump through some extra hoops to get the information. Police officer Calvin Chang had previously settled a lawsuit with UC Davis over race and sexual orientation discrimination, but believed that recent comments on the Vanguard of Davis blog may have been from university insiders attempting to discredit him—a breach of the settlement he had reached with the university.

Chang attempted to subpoena to have the commenters identified, but the judge did not immediately go along with it. Instead, she ruled that Chang could hire an investigator to find out whether the commenters were "managing agents of the university." If they are, then they would indeed be in breach of Chang's settlement and the judge will permit their identities to be revealed so that he could pursue further action.

Of course, the only way to truly avoid being outed and sued is to avoid saying controversial things online in the first place, but that goes against the open spirit of the Internet. "You don't get to pick and choose whose speech is important and whose isn't," Zimmerman said. Unless litigants have a legitimate need for people's personal information to go forward with a lawsuit, it's worth fighting back to not only protect your own rights, but the rights of others online as well.