The U.S. Supreme Court declined to intervene yesterday in an ongoing argument over the proper boundaries for federal surveillance of suspected terrorists, rebuffing an attempt by civil liberties advocates to challenge the Bush administration on the issue.

The American Civil Liberties Union, the National Association of Criminal Defense Lawyers and Arab American groups had asked the high court to consider whether the government had gone too far in permitting information gathered with secret Foreign Intelligence Surveillance Act warrants to be used in criminal prosecutions.

The justices declined to allow the groups to intervene in the case, but they did not issue a decision on the merits of either side.

The ACLU had taken the novel step of filing an appeal on behalf of people who did not know they were being monitored in an attempt to bring the case before the high court. The organization said it was disappointed but not surprised by the justices' decision to reject that effort.

"It was an unusual case because there was no one able to appeal the government's power to spy on ordinary Americans," said Ann Beeson, the ACLU's associate legal director. "We are not going to give up on our many different attempts to challenge these new spying powers."

Attorney General John D. Ashcroft praised the decision and defended "the government's lawful actions to detect and prevent international terrorism and espionage within our borders.

"It is vitally important that the government's intelligence and law enforcement officials coordinate their efforts to protect America from foreign threats to our national security," Ashcroft said in a statement.

The dispute revolves around powers granted to the government as part of the USA Patriot Act, a far-reaching set of anti-terrorism measures approved in the wake of the Sept. 11, 2001, attacks.

The court that oversees government spying, the Foreign Intelligence Surveillance Court, ruled last year that the government was overstepping its bounds and, in an unprecedented public opinion, said Ashcroft's proposed rules "were not reasonably designed" to protect privacy rights.

But the FISA appellate panel, considering its first case, overturned that ruling in November, concluding that the government was free to implement more aggressive tactics in conducting searches and surveillance of suspected terrorists.