INDIANAPOLIS – American-born Taliban fighter John Walker Lindh says a federal prison rule barring him and other Muslims from praying together daily is “absurd” and contends the U.S. is causing him to sin against his religion by prohibiting such gatherings in the name of security.

Lindh testified Monday in U.S. District Court in Indianapolis during a trial in a civil lawsuit seeking to overturn the prison policy, which he argues violates a 1993 law barring the government from curtailing religious expression without showing it has a compelling interest.

Lindh, serving a 20-year sentence for aiding Afghanistan’s Taliban government before its overthrow, is one of 43 inmates housed in a closely monitored unit at the federal prison in Terre Haute. Twenty-four of them are Muslim.

Inmates in the tightly controlled Communications Management Unit – one of only two in the country – are allowed to eat, talk, play cards and exercise as a group, but praying together is limited to once a week except during the Islamic holy month of Ramadan. Most days, they must pray alone in their individual cells.

Lindh, 31, said the restrictions violate his school of Islam, which requires group prayer five times a day, if possible.

“I believe it’s obligatory,” Lindh said of the daily group prayer. “If you’re required to do it in congregation and you don’t, then that’s a sin.”

The government maintains that preserving security in the unit, where inmates’ contact with the outside world is restricted and most of their movements are under audio and video surveillance, makes it necessary to limit group activities.

“There are no legitimate security risks by allowing us to pray in congregations,” Lindh said. “It’s absolutely absurd.”

Monday’s courtroom appearance was a rare one for Lindh, who has been held at the Terre Haute prison since 2007.