(CNN) -- John Walker Lindh, who is serving a 20-year sentence for aiding the Taliban, testified in federal court Monday in Indianapolis in an attempt to overturn a prison ban that he says severely restricts Muslim prayer.
Lindh spent more than two hours on the witness stand in a lawsuit he filed against the warden and the federal prison in Terre Haute, Indiana, alleging the warden's ban on daily group prayer violates the Religious Freedom Restoration Act.
"He addressed his personal need to pray, to pray in congregation and how he was able to do it previously on the unit before it was stopped," Lindh lawyer Kenneth Falk said. "Being forced to pray in his cell is not a satisfactory alternative."
The warden, according to court documents, has argued that the ban implemented after 2007 is necessary because of security concerns.
The plaintiffs concluded their case Monday afternoon, but the government is expected to take at least another day to present its case. Falk said.
Lindh, 31, is serving his sentence in Terre Haute's Communications Management Unit, which opened in 2006. The unit severely restricts the contact of prisoners with the outside and monitors conversations between the inmates.
The unit has 55 cells, and the majority of the prisoners are Muslim, according to court documents.
Also housed with Lindh, according to published reports, are members of the "Lackawanna Six," a group of Yemeni-American friends who were convicted of providing material support to al Qaeda; Ali Asad Chandia, convicted of providing aid to a Pakistani terror organization; and Enaam Arnaout, who pleaded guilty to using donations to his charitable foundation to support fighters in Bosnia.
At least five inmates, including Arnaout and Chandia, gave depositions in support of the lawsuit.
Islam requires followers to answer a call to pray five times day. Depending on the religious teaching, the call could be required to be a group prayer.
Part of Lindh's complaint alleges that before 2007, Muslim prisoners were allowed to pray together in the unit for at least three of Islam's five daily prayers. Since then, other than during the holy month of Ramadan, the prisoners are allowed to gather only once a week, according to court documents.
The court filings also gave a glimpse inside the prison unit, describing it as "an open unit, meaning that they have freedom to move around various places in the unit during the times they are not restricted in their cells."
There is an area with a computer where they can send e-mail, a food services area with tables and a microwave, a lounge area with multiple televisions, a room with exercise equipment and a room with a washer and dryer, the records said.
The warden, who was not identified by name in the records, implemented the ban after the Muslim prisoners, who were engaged in prayer, did not acknowledge a unit lockdown prompted by a fire alarm.
The prisoners said they did not hear the lockdown because of a noisy fan.
Lindh, who was born in California, converted to Islam as a teenager.
He traveled to Afghanistan in 2001 and attended a terror training camp where he was introduced to Osama bin Laden.
Lindh was captured by the Afghan Northern Alliance on November 25, 2001, and imprisoned in a compound in Mazar-e-Sharif, where he was questioned by CIA agent Johnny Michael Spann, who was killed in an uprising at the compound a short time later.
As part of a deal, Lindh pleaded guilty to supplying services to the Taliban and carrying an explosive during the commission of a felony. His family filed a petition for clemency to commute the 20-year sentence, a request that was denied by President George W. Bush in one of his final acts in office.