WASHINGTON — A report to Congress released Friday concluded that the Bush administration's defense of the National Security Agency's domestic spying program was not as "well-grounded" in the law as the White House claimed.
The report by the nonpartisan Congressional Research Service is the most comprehensive analysis yet of legal arguments for President Bush's authorization of warrantless eavesdropping in the U.S.
The findings probably will fuel the heated debate over the NSA program as Congress prepares for hearings on it as early as next month, liberal and conservative legal analysts said.
The report's authors conclude that, based on what is now known about the secret NSA operation, "it appears unlikely" that a court would find that Congress had given Bush the authority to initiate such a program.
The report says the administration should have sought warrants from the secret court that oversees such operations before allowing the NSA to listen in on conversations.
In response to the report, a Justice Department spokesman, Brian Roehrkasse, said the activities "described by the president were conducted in accordance with the law to provide a critical tool in the war on terror that saves lives and protects civil liberties at the same time."
Bush and others in his administration have argued that the 1978 law that governs such surveillance activities, the Foreign Intelligence Surveillance Act, is ill-suited to the demands of fighting terrorism after Sept. 11.
Administration officials have said that it would be too cumbersome for the NSA to seek approval for each intercepted communication in the government's fast-moving campaign against Al Qaeda and other foreign terrorist organizations.
Bush also has argued that he has the authority to order the NSA program under his constitutional power as commander in chief and under a congressional resolution, passed after the Sept. 11 terrorist attacks, that authorized him to use "all necessary and appropriate force" against the perpetrators of the attacks.
In their 44-page report, authors Elizabeth B. Bazan and Jennifer K. Elsea said the Bush administration's argument, taken to its logical conclusion, would put no limit on what the government could do. In addition, they said: "It is not clear that the collection of intelligence constitutes a use of force."
With regard to the president's wartime powers, the authors take the unusual step of critiquing the only ruling of the secret Foreign Intelligence Surveillance Act's Court of Review that has been made public.
The court said, "We take for granted that the president does have that authority" to conduct searches without a warrant. The administration cites the ruling as a key basis for the president to conduct such searches. But the Congressional Research Service report contends that the precedents that underlie that assumption all predated the 1978 Foreign Intelligence Surveillance Act and therefore are suspect.
One of the administration's key arguments for why it did not seek to change the act to accommodate the domestic spying program was that it would have revealed the existence of the highly classified operation.
But the report's authors say that there are many ways for officials to discuss classified matters with Congress and request legislative changes, and that "no legal precedent" supports such presidential authority.
On Monday, Bush said again that he had the authority to order the surveillance. "The enemy is calling somebody, and we want to know who they're calling and why," Bush said in San Antonio. "And that seems to make sense to me, as the commander in chief, if my job is to protect the American people."