I am frequently contacted by individuals and organizations being defamed by anonymous commenters to online stories in major digital publications (Wikipedia is very common for these kinds of issues as well). There is a path to (potentially) identify the individual(s) behind these kinds of comments, but it is sometimes complex and time consuming. As this case shows, however, it is possible.
To the point, an Idaho newspaper was ordered by a judge to provide identifying information about a commenter who suggested that a politician had stolen money which is missing from a local political party office. It’s notable that the comment which led to the subpoena was whether the missing money may have been “stuffed inside Tina’s (party chairwoman Jacobson’s) blouse.”
Jacobson subpoenaed the identifying information, and the newspaper (as is typical in these cases) sought to quash. Judge John Luster ruled:
In his written decision, Luster pointed out that the U.S. Supreme Court has ruled since 1942 that the First Amendment does not protect defamatory speech. “… while the individuals are entitled to the right of anonymous free speech, this right is clearly limited when abused,” Luster wrote.
He ordered the newspaper to give to the plaintiff “any document establishing the identity, e-mail address, and IP (Internet Protocol) addresses of ‘almostinnocentbystander.’”
It’s notable that while the identifying information may provide definitive identity of the poster, that is not assured, or further subpoenas may be required.
In my practice, I use a variety of techniques to identify gadflys, via both investigation of public sources, and litigation support.I also use a variety of other techniques to remove their comments, and restrict their ability to repost them.