On Dark Web sites like the Silk Road black market and its discussion forums, anonymous visitors could write even the most extreme libertarian and anarchist statements without fear. The rest of the internet, as a few critics of the US judicial system may soon learn, isn't quite so free of consequences.

Last week the Department of Justice issued a grand jury subpoena to the libertarian media site Reason.com, demanding that it identify six visitors to the site. The subpoena letter, obtained and published by blogger Ken White, lists trollish comments made by those six Reason readers that—whether seriously or in jest—call for violence against Katherine Forrest, the New York judge who presided over the Silk Road trial and late last month sentenced Silk Road creator Ross Ulbricht to life in prison.

"It's judges like these that should be taken out back and shot," wrote one user named Agammamon, in a comment thread that has since been deleted from Reason.com's story on Ulbricht's sentencing.

"It's judges like these that will be taken out back and shot," answered another user named Alan.

"Why do it out back? Shoot them out front, on the steps of the courthouse," reads a third comment from someone going by the name Cloudbuster.

The subpoena calls for Reason.com to hand over data about the six users, including their IP addresses, account information, phone numbers, email addresses, billing information, and devices associated with them. And it cites a section of the United States criminal code that forbids "mailing threatening communications." When those communications threaten a federal judge, they constitute a felony punishable by as much as 10 years in prison. (The average internet user has no such protection.)

"We command you that all and singular business and excuses being laid aside, you appear and attend before the grand jury of the people of the United States," reads the subpoena signed by US Attorney Preet Bharara and assistant US attorney Niketh Velamoor. In an accompanying letter, Velamoor asks that the subpoena not be publicly revealed: "The Government hereby requests that you voluntarily refrain from disclosing the existence of the subpoena to any third party."

When WIRED called Department of Justice investigator Maxime Vales, who is named in the subpoena as the intended recipient of the users' data, he declined to comment. Reason.com didn't respond to WIRED's request for comment.

Forrest surprised many Silk Road watchers with her life sentence for Ulbricht, who was convicted on five felony counts that included a "kingpin" statute for running an organized crime operation. Even the prosecution had asked for only a sentence "substantially more than the mandatory minimum" of 20 years—not life. “Silk Road’s birth and presence asserted that its…creator was better than the laws of this country," Forrest told Ulbricht at sentencing. "This is deeply troubling, terribly misguided, and very dangerous.”

The Reason.com incident marks the second such subpoena in the past few months to result from law enforcement's clash with the Dark Web. In March, the Department of Homeland Security subpoenaed the "darknetmarkets" forum on Reddit, seeking identifying information about several users who may have been associated with Evolution, another Dark Web black market that followed in the Silk Road's footsteps.

It's hard to imagine the Reason.com commenters actually intended violent action against Forrest, so much as the typical trollish provocation that fills so many web comment sections. Whether their comments were actually illegal remains a tough constitutional gray area; the Supreme Court has ruled that only "true threats" aren't protected by the First Amendment's free speech protection. Determining whether a threat is "true" requires a still-unsettled legal calculation that may factor in both the threat target's reaction to the statement and the "intent" of the commenter.1

But in fact, Forrest has been threatened before—and more explicitly—on the Dark Web site the Hidden Wiki, and even had her personal information published, including a purported home address. "I hope some drug cartel that lost a lot of money with the seizure of silk road will murder this lady and her entire family," wrote a user named ServingJustice, who also published Forrest's personal info.

Compared with that "doxing," Forrest's more recent critics on Reason's website made what appear to be only idle threats. But they did so outside of the Dark Web's anonymity protections. And if Reason coughs up their personal data to Grand Jury investigators, they may come to regret it.

1Correction 6/10/2015: An earlier version of this story stated that regardless of the commenters' intent, their statements were illegal under federal statutes protecting officials from threatening speech. In fact, only "true threats" would be illegal, and the definition of a true threat may involve the commenters' intent.