The United States for the first time plans to use information gathered from warrantless surveillance as evidence against a terrorism suspect.
The suspect, Jamshid Muhtorov, is in jail in Colorado. The FBI arrested him last year for allegedly providing material aid to the Uzbek terror group Islamic Jihad Union.
Federal agents monitored communications between Muhtorov and the administrator of a website associated with the group.
In a court filing, the Justice Department informed Muhtorov's lawyers that it plans to use these communications as evidence.
It is the first time since the Foreign Intelligence Surveillance Act was amended in 2008 that the government acknowledges using such evidence to prosecute a suspect in a criminal case.
The law allows U.S. agents to listen in on communications between citizens and foreign entities without a court order.
The Supreme Court has refused to hear challenges to the law, saying the plaintiffs could not prove they were deliberately targeted.
Legal experts say the Muhtorov case could wind up before the court.
Some information for this report was provided by AP.