© Haraz N. Ghanbari/Associated Press
Solicitor General Donald B. Verrilli Jr. said defendants had a right to know if prosecutors had relied on wiretaps.

The Justice Department for the first time has notified a criminal defendant that evidence being used against him came from a warrantless wiretap, a move that is expected to set up a Supreme Court test of whether such eavesdropping is constitutional.

Prosecutors filed such a notice late Friday in the case of Jamshid Muhtorov, who was charged in Colorado in January 2012 with providing material support to the Islamic Jihad Union, a designated terrorist organization based in Uzbekistan.

Mr. Muhtorov is accused of planning to travel abroad to join the militants and has pleaded not guilty. A criminal complaint against him showed that much of the government's case was based on intercepted e-mails and phone calls.

The government's notice allows Mr. Muhtorov's lawyer to ask a court to suppress the evidence by arguing that it derived from unconstitutional surveillance, setting in motion judicial review of the eavesdropping.

The New York Times reported on Oct. 17 that the decision by prosecutors to notify a defendant about the wiretapping followed a legal policy debate inside the Justice Department.

The debate began in June when Solicitor General Donald B. Verrilli Jr. discovered that the department's National Security Division did not notify criminal defendants when eavesdropping without a warrant was an early link in an investigative chain that led to evidence used in court. As a result, none of the defendants knew that they had the right to challenge the warrantless wiretapping law.

The practice contradicted what Mr. Verrilli had told the Supreme Court last year in a case challenging the law, the FISA Amendments Act of 2008. Legalizing a form of the Bush administration's program of warrantless surveillance, the law authorized the government to wiretap Americans' e-mails and phone calls without an individual court order and on domestic soil so long as the surveillance is "targeted" at a foreigner abroad.

A group of plaintiffs led by Amnesty International had challenged the law as unconstitutional. But Mr. Verrilli last year urged the Supreme Court to dismiss the case because those plaintiffs could not prove that they had been wiretapped. In making that argument, he said a defendant who faced evidence derived from the law would have proper legal standing and would be notified, so dismissing the lawsuit by Amnesty International would not close the door to judicial review of the 2008 law. The court accepted that logic, voting 5-to-4 to dismiss the case.

In a statement, Patrick Toomey, staff attorney with the American Civil Liberties Union, which had represented Amnesty International and the other plaintiffs, hailed the move but criticized the Justice Department's prior practice.

"We welcome the government's belated recognition that it must give notice to criminal defendants who it has monitored under the most sweeping surveillance law ever passed by Congress," Mr. Toomey said. "By withholding notice, the government has avoided judicial review of its dragnet warrantless wiretapping program for five years."

The Justice Department change traces back to June, when The Times reported that prosecutors in Fort Lauderdale and Chicago had told plaintiffs they did not need to say whether evidence in their cases derived from warrantless wiretapping, in conflict with what the Justice Department had told the Supreme Court.

After reading the article, Mr. Verrilli sought an explanation from the National Security Division, whose lawyers had vetted his briefs and helped him practice for his arguments, according to officials with knowledge of the internal deliberations. It was only then that he learned of the division's practice of narrowly interpreting its need to notify defendants of evidence "derived from" warrantless wiretapping.

There ensued a wider debate throughout June and July, the officials said. National security prosecutors raised operational concerns: disclosing more to defendants could tip off a foreign target that his communications were being monitored, so intelligence officials might become reluctant to share crucial information that might create problems in a later trial.

Mr. Verrilli was said to have argued that there was no legal basis to conceal from defendants that the evidence derived from legally untested surveillance, preventing them from knowing they had an opportunity to challenge it. Ultimately, his view prevailed and the National Security Division changed its practice going forward, leading to the new filing on Friday in Mr. Muhtorov's case.

Still, it remains unclear how many other cases - including closed matters in which convicts are already service prison sentences - involved evidence derived from warrantless wiretapping in which the National Security Division did not provide full notice to defendants, nor whether the department will belatedly notify them. Such a notice could lead to efforts to reopen those cases.