Updated at 6:56 p.m. ET
An American Civil Liberties Union lawyer said Thursday his organization is helping two anonymous Twitter users fight an effort by prosecutors to unmask them after they tweeted criticism of a Pennsylvania attorney general who is running for governor.
ACLU attorney Vic Walczak said he will ask a judge to throw out a subpoena seeking the identities of the two Twitter users, "bfbarbie" and "CasablancaPA," if an agreement with Attorney General Tom Corbett's office can't be worked out.
Walczak said the subpoena by a statewide investigative grand jury is an unconstitutional retaliation that violates First Amendment free-speech protections.
"It's a prized American right to criticize government officials, and to do so anonymously," Walczak said.
A Corbett spokesman said the subpoena was partly related to a Friday sentencing hearing for former Democratic legislative aide Brett Cott. He is one of three people convicted in March of public corruption charges in the ongoing investigation into the alleged illegal use of legislative employees and government resources to run political campaigns.
The grand jury on May 6 subpoenaed the identities and other information about the two users from Twitter Inc. Corbett's office has been using the highly secretive grand jury process for the past several years to look into allegations that government resources and legislative employees have been illegally used to run political campaigns.
Twitter attorney Timothy Yip issued a statement that the company only discloses user information under "limited circumstances."
If the company believes it is legal to do so, Twitter notifies users whenever it receives requests for their information that it believes it is obligated to share, Yip said.
"This policy is designed for maximum transparency and gives users an opportunity to object," he said.
A Twitter spokesman said the company had not turned over any information to Corbett's office as of Thursday afternoon.
Attorney general's office spokesman Kevin Harley said the subpoena "has nothing to do with criticisms of the attorney general."
"There are many bloggers and other Web sites that are critical of the attorney general," Harley said. "That's not what this is about."
Grand jury secrecy makes it difficult, if not impossible, to know why the identities of bfbarbie and CasablancaPA are being sought.
But in an interview with the AP last year, Corbett said he was aware of anonymous critics of his investigation, and mentioned Cott by name.
"We know people like Brett Cott are on the blogs all day, making stuff up," Corbett said.
Cott was an aide to former Rep. Mike Veon, D-Beaver, who also was convicted of multiple counts. Veon's sentencing is scheduled for next month.
Twitter user CasablancaPA links to an anonymous blog, "CasablancaPA: Exposing the hypocrisy of Tom Corbett," which also has criticized Corbett and how his office has handled the investigation of the Legislature known as Bonusgate.
On Twitter, both CasablancaPA and bfbarbie have been critical of Corbett and the Bonusgate prosecution.
In a tweet Thursday, bfbarbie called Corbett "an evil man," and CasablancaPA wrote that Corbett "should try reading the blog he wants to shut down a little more closely."
A sentencing memorandum filed by prosecutors on Wednesday accused Cott of having "extensively and anonymously utilized" the CasablancaPA blog "to deflect blame and deny responsibility for his criminal conduct and to attack and malign the investigative and prosecutorial process."
Walczak said the deadline for Twitter to respond to the subpoena was recently moved up from Friday to Thursday, further suggesting to him it may somehow be connected to Cott's sentencing.
Cott and his lawyer both declined comment about CasablancaPA - the blog or the Twitter user - on Thursday.
Bryan Walk, Cott's defense attorney, said the grand jury was wrong to issue the subpoena, however.
"They are completely abusing the process trying to seek this information," Walk said.
Walk said he was considering seeking a sentencing delay.