Meanwhile, legal experts worry that the once-obscure "material-witness" statute is being used to undermine a basic tenet of American justice.
"It's such a violation of our fundamental principles in this country," said Kate Martin, director of the Center for National Security Studies, one of the civil-rights groups to file suit. People should be jailed "when they are charged, not otherwise."
As part of the federal criminal code, the material-witness statute gives prosecutors an important tool to hold people who may have information about crimes, said Juliette Kayyem, a terrorism law expert at Harvard University's Kennedy School of Government.
"What we've seen since Sept. 11 is its abuse by the Department of Justice," she said.
A U.S. citizen's arrest
The material-witness law came under a spotlight last week, with the government indicting Maher "Mike" Hawash, 38, an American citizen who had been jailed for 40 days without knowing whether he was a witness or a suspect.
The software engineer had been arrested as a material witness March 20 by the FBI as he arrived for work at Intel Corp. in Portland, Ore. His coworkers, friends and family rallied to his defense. Before Hawash, most arrested were foreign nationals.
On Monday, the government charged Hawash with conspiring to "levy war" against the United States and provide material support to al-Qaeda. He allegedly was the seventh member of a Portland sleeper cell that failed to reach Afghanistan via China. The others were indicted last fall.
But charging Hawash has failed to silence critics of government tactics.
"They didn't want him as a witness. They wanted him as a defendant, and that's not a proper use of the material-witness statute," said David Rudovsky, a Philadelphia civil-rights lawyer.
"It's an abuse of authority to jail someone who you have targeted as a potential criminal suspect under the guise of trying to obtain his testimony in front of a grand jury," said Martin, whose lawsuit seeks disclosure on all arrests post-9/11, not just those of material witnesses.
Last year, her group counted 25 material-witness arrests, drawing largely from news stories about individuals. The Washington Post has reported finding at least 44 people, including seven U.S. citizens.
There have been no material-witness arrests in terrorism cases in the Philadelphia region, according to U.S. Attorney Patrick Meehan. "On rare occasions it is imperative to secure the appearance of a witness. We carefully balance that need against the restriction on the defendant's liberty."
In the past, the 1984 material-witness law was used largely in organized-crime cases. To get an arrest warrant, the prosecutor must show the judge that the person's testimony "is material in a criminal proceeding" and that the person is a reluctant witness or likely to flee. The person is entitled to a lawyer.
Bryan Sierra, a Justice Department spokesman, said last month that there had been misconceptions about those arrested.
Judges review arrests and those arrested have lawyers. "There are safeguards in place and the government follows those safeguards to the letter," Sierra said.
Another U.S. citizen, Jose Padilla, was arrested in Chicago last spring as a material witness and held for a month before the government accused him of plotting with al-Qaeda to explode a radioactive "dirty bomb." He was transferred to military custody.
James Ujaama, a Seattle community activist, was held for five weeks before being charged with providing support to al-Qaeda. He recently pleaded guilty.
Zacarias Moussaoui, a French citizen of Moroccan descent, was apprehended in Minnesota about three weeks before the Sept. 11 attacks, after his behavior at a flight school aroused suspicion. He was held for four months as a material witness until he was indicted as a conspirator in the Sept. 11 attacks.
Mark A. Drumbl, a law professor at Washington & Lee University who is tracking the government's prosecution of terrorism, said the Hawash case underscored the need to consider the constitutional rights of material witnesses.
"I think it becomes important to think long and hard whether material-witness detainees have a right to see documents related to their detention, have a right to Miranda warnings, have a right to consult with counsel, and even have a right to challenge their detention after a certain period of time," Drumbl said.
"This is pretty major and needs to be talked about."
Contact staff writer Rose Ciotta
at 215-854-5024 or email@example.com.