A lot of information about each of us is already available on the Internet. However, it is illegal to post private information about a person with the intention of causing harm or damaging his/her reputation.
Answer Applies to: Nebraska
This may very well be illegal under different state and federal laws. Which laws have been broken depend on a number of factors. First, what is your friend's job? Second, which information was posted? Was his home address or phone or private email posted? Third, on what kind of site was the information posted? And what was the purpose of posting the information? Was it done to threaten, endanger, humiliate, or harm him? And fourth, in what state does he reside? Fifth, were there any extortion demands, such as a demand for money or a demand that the person do something to avoid having their information posted. Sixth, what is the age of the person? Many states have laws specifically against stalking a young person in this way.
There are federal laws against posting personal information of federal employees. There are state laws against posting information about police or emergency workers. There are state privacy laws. There are federal and state laws against using the internet to harass or endanger any person. The names for the laws will be cyberstalking, intimidation, cyberbullying, obscene posting, computer abuse, interstate harassment or interstate abuse. Even if the perpetrator and victim are in the same state, if it is done on the internet, it is interstate because the internet itself is interstate.
There are laws in some states about posting any person's name or photo onto any website that contains any pornographic or obscene materials. That is what makes it illegal in some states to post onto the website Encyclopedia Dramatica, which is used to stalk and extort people, illegal. Encyclopedia Dramatica is a website that contains shocking obscenity. The admins or users of the site are apparent sociopaths who use the site to control and harm others through defamation and public shaming. They post peoples' names and info on the site, thus linking the innocent victims to this shocking abuse. Is it illegal? Yes, under many laws. The perpetrator owners of the site seem to mistakenly believe they are immune from prosecution because they have placed their server outside the U.S. Since their victims, and even some of them, are inside the U.S., they are still very much under U.S. criminal jurisdiction.
There is also the notorious Doxbin, where people post others' information. This is also illegal because the people are being threatened, harassed, and opened to danger such as stalking, fraud, attack, and assassination.
There is a mistaken notion or mythology that if something can be found someplace on the internet, that it is legal to post it anywhere else on the internet. This is simply not true. As shown in the example of Encyclopedia Dramatica, placing a person's name or photo or information on a site with obscenity, or with the purpose of harassing them, is illegal. Yes, those pieces of information may be located elsewhere on the internet, but placing them onto a disgusting website to harm the people makes it illegal. Same with Doxbin. The purpose of Doxbin is to endanger the people whose information is listed. Of course this is illegal.
By way of disclosure, I have personally been a victim of both Doxbin and Encyclopedia Dramatica, as well as some other extortion and harassment sites run by sociopaths and stalkers. The people from Doxbin and Encyclopedia Dramatica sent me threats, extortion demands, and a very detailed death threat. This is all in the hands of law enforcement. If your friend has been harassed by either site, tell him or her to please hurry and file a complaint. The tendency can be to shy away, but I think reporting loudly and insistently is the only thing that will close down these abusive sites and put the perpetrators in prison.
Your friend should report these crimes to as many agencies as needed to get one to handle it effectively. That may be the FBI, the IC3, the local police. The FBI can be reached via online tipline, as can the IC3. I strongly recommend that your friend report the situation and keep persisting until it is remedied.
Answer Applies to: California