( CNN ) -- A decision by Massachusetts prosecutors to subpoena the Twitter records of an Occupy Boston activist , as well as records linked to two Twitter hashtags , has free speech advocates up in arms , calling the move a violation of the First Amendment . Suffolk County prosecutors demanded that Twitter hand over information posted on the social media website by user `` Guido Fawkes , '' whose Twitter handle is @ p0isAn0N , as well as information from the user behind @ OccupyBoston and those who Tweeted # BostonPD or # d0xcak3 , according to the document . The ACLU gave CNN a copy of the subpoena . `` There is a constitutional right to write things on the Internet , '' said Peter Krupp , an attorney with the ACLU of Massachusetts who is representing the person using the Twitter handle Guido Fawkes . `` There is a constitutional right to do that anonymously . '' A Suffolk County Superior judge held a private hearing Thursday and impounded all documents pertaining to the case , according to Krupp , who said he could not divulge what happened during the session . Krupp said he had requested that the meeting be open to the public . `` Secret court proceedings , particularly proceedings involving First Amendment issues , are troubling as a matter of both law and democracy , '' said Carol Rose , executive director for the ACLU of Massachusetts , in a statement . Suffolk County District Attorney spokesman Jake Wark said that , since Thursday 's court proceeding was not public , prosecutors could not comment on the hearing . `` We investigate and prosecute criminal acts , '' Wark said . `` We have no interest in investigating political speech or political opinions . '' In the subpoena , which was issued on Dec. 14 , prosecutors requested that Twitter release to them `` all available subscriber information , '' including IP address logs for the time period between Dec. 8 and Dec. 13 as part of an `` official criminal investigation . '' Those dates coincide with clashes between protesters and police in Boston 's Dewey Square . Dozens of protesters were arrested after refusing to leave the public space after being ordered to do so by Boston 's mayor , Thomas Menino . Wark would not elaborate on the nature of the criminal investigation , but said Thursday that `` no charges have been brought against any individual . '' Prosecutors had requested that Twitter keep the subpoena confidential , but it was posted online last week and has been viewed by more than 20,000 people , Krupp said . Subpoenaing Twitter records is becoming more common , according to lawyer Ethan Wall , of the Richman Greer law firm in Miami . Wall , who specializes in intellectual property litigation , said the practice could have `` a chilling effect on free speech . '' `` We are in this information-accessible age where we can post anything and everything from anywhere on any device , '' Wall said . `` Because it 's so easy I do n't think that people put the thought into how this might affect them personally , professionally or legally . '' Henry J. Cittone of Cittone & Lindenbaum LLP , an intellectual property law firm in New York , said the most troubling part of the case is that prosecutors are subpoenaing hashtags , meaning that anyone who Tweeted or re-Tweeted # BostonPD or # d0xcak3 could be exposed during the investigation . `` It looks like authorities are trying to build lists of protestors by using hashtag information , as opposed to going after actual criminals -- which would have been the proper focus of such an investigation , '' Cittone said . Krupp called the subpoena `` wildly over-broad , '' pointing out that requesting records of two Twitter handles -- @ p0isAn0N and @ OccupyBoston -- could affect thousands . `` That 's not just subscriber information for those accounts , but presumably followers , '' he said . Twitter did not respond to requests for comment . A posting on its website says : `` We may preserve or disclose your information if we believe that it is reasonably necessary to comply with a law , regulation or legal request ; to protect the safety of any person ; to address fraud , security or technical issues ; or to protect Twitter 's rights or property . ''
Massachusetts prosecutors seeking Twitter records of Occupy activist . ACLU calls it a violation of the First Amendment . Score: 6 Prosecution spokesman says he can not comment .