CINCINNATI — The Bush administration may continue its warrantless surveillance program while it appeals a judge's ruling that the program is unconstitutional, a federal appeals court ruled yesterday.

The president says the program is needed in the war on terrorism; opponents say it oversteps constitutional boundaries on free speech, privacy and executive powers.

The unanimous ruling by a three-judge panel of the 6th U.S. Circuit Court of Appeals allows the program to continue during the appeal, which could take months.

In their brief order in ACLU v. National Security Agency, the judges said they balanced the likelihood of success of an appeal, the potential damage to either side and the public interest.

The American Civil Liberties Union, which filed the lawsuit challenging the program in January, says it hopes for a ruling by the end of the year.

"We are confident that when the 6th Circuit addresses the merits of this case, it will agree that warrantless wiretapping of Americans violates the law and is unconstitutional," Melissa Goodman, an ACLU attorney, said in a news release.

Deputy White House press secretary Dana Perino said the president viewed the program as critical to preventing terrorist attacks.

"We are pleased to see that it will be allowed to continue while the Court of Appeals examines the trial court's decision, with which we strongly disagree," Perino said.

"This program is both critical to preventing terrorist attacks and fully consistent with law," said Justice Department spokesman Brian Roehrkasse.

The appeal on the merits wouldn't necessarily go to the same three-judge panel that granted the stay yesterday: Julia Smith Gibbons, a Bush appointee; Ronald Lee Gilman, appointed by President Bill Clinton; and Alice M. Batchelder, appointed to the court by President George H.W. Bush.

U.S. District Judge Anna Diggs Taylor in Detroit ruled Aug. 17 that the program, which targets communications between people in the U.S. and people overseas with a suspected link to terrorism, is unconstitutional. She refused Sept. 28 to postpone her ruling during appeals, but gave the government a week to ask the 6th Circuit to stop it from taking effect.

The Justice Department had urged the appeals court to allow it to keep the program in place while it appeals, claiming that the nation faced "potential irreparable harm."

"The country will be more vulnerable to a terrorist attack," the government motion said.

The Justice Department is challenging Taylor's ruling that the effort, which it calls the Terrorist Surveillance Program, violates the rights to free speech and privacy, as well as the separation of powers in the Constitution.

The White House says the surveillance is a key tool in the fight against terrorism and has already helped prevent attacks.

The ACLU filed the suit behalf of journalists, scholars and lawyers who say the program of warrantless wiretaps of phone and Internet communication has made it difficult for them to do their jobs because they believe many of their overseas contacts are likely targets. Many said they had been forced to take expensive and time-consuming overseas trips because their contacts wouldn't speak openly on the phone or because they didn't want to violate their contacts' confidentiality.

Similar lawsuits challenging the program have been filed by other groups, including in New York and San Francisco. Taylor, appointed by President Jimmy Carter, was the first judge to rule the National Security Agency program unconstitutional. The issue could wind up before the U.S. Supreme Court.

The president has said he strongly disagrees with Taylor's August decision, saying those who support her view "simply do not understand the nature of the world in which we live."

"This country of ours is at war," Bush said the day after her ruling. "And we must give those whose responsibility it is to protect the United States the tools necessary to protect this country in a time of war."

In her ruling, Taylor said the Bush administration appeared to be saying the president had the "inherent power" to violate laws of Congress.

"There are no hereditary kings in America and no powers not created by the Constitution. So all 'inherent powers' must derive from that Constitution," Taylor wrote in a 43-page opinion. "The public interest is clear, in this matter. It is the upholding of our Constitution."

The ACLU says the 1978 Foreign Intelligence Surveillance Act, which set up a secret court to grant warrants for such surveillance, gave the government enough tools to monitor suspected terrorists.

"Every time the NSA engages in warrantless wiretapping, they are violating the law and the United States Constitution," ACLU attorney Goodman said last month.

The government says it can't always wait for a court to take action. It says the NSA program is well within the president's authority but proving that would require revealing state secrets.