A federal judge ruled yesterday in a landmark decision that the use in court against immigrants of classified terrorism evidence that they are not allowed to see is unconstitutional.

U.S. District Judge William Walls in Newark, N.J., ordered the defendant in the case, Hany Kiareldeen, a 32-year-old Palestinian immigrant, released. Kiareldeen had been held by the Immigration and Naturalization Service since March 1998 pending deportation proceedings because the FBI's Joint Terrorism Task Force had developed secret information that he had hosted a meeting with terrorists planning the World Trade Center bombing at his home and had talked of murdering Attorney General Janet Reno.

"The court cannot justify the government's attempt to 'allow [people] to be convicted on unsworn testimony of witnesses--a practice which runs counter to the notions of fairness on which our legal system is founded,' " ruled Walls.

The use of classified evidence in some immigration proceedings was first authorized by the 1996 anti-terrorism bill that followed the World Trade Center and Oklahoma City bombings. The controversial provision has been used in approximately two dozen cases around the country in which the INS asserted national security concerns as the basis for depriving immigrants of the right to examine and confront adverse witnesses and evidence. All of the cases are against Arab or Muslim immigrants.

"For the first time, a federal court has weighed the constitutionality of the use of secret evidence and found it unconstitutional. This may call into question other INS proceedings where classified information has been used," said Juliette Kayyem, a former Justice Department attorney and current member of the National Commission on Terrorism charged by Congress with assessing U.S. terrorism laws.

The FBI reports detailing the source of the information linking Kiareldeen to terrorists were not divulged to Kiareldeen or his attorneys. Kiareldeen denied the charges and said they were likely to have come from his ex-wife, with whom he was involved in a custody dispute.

Kiareldeen had lived in the United States since 1990, when he entered from Israel on a student visa. In 1994, he married and had a daughter. After a bitter divorce, he remarried and petitioned to become a permanent resident. The INS and FBI arrested him for overstaying the period of his student visa and argued he should be deported on the basis of the FBI terrorism information.

"Despite repeated requests from the Immigration Judge, the government made no recorded efforts to produce witnesses, either in camera or in public, to support its allegations of terrorism. The petitioner was thus denied the opportunity to meaningfully cross-examine even one person during his extended detour through the INS administrative procedures," Judge Walls wrote in his opinion. "The INS actions unconstitutionally damaged Kiareldeen's due process right to confront his accusers."