A former Justice Department official’s riveting congressional testimony about his agency’s showdown with the White House over a secret eavesdropping program in 2004 could spell trouble for the government’s attempts to fend off dozens of pending lawsuits challenging the surveillance effort.

Appearing before the Senate Judiciary Committee on Tuesday, the deputy attorney general from 2003 to 2005, James Comey, described how he refused to certify the legality of the program, prompting White House officials to try to reverse the department’s stance through an in-person, late night appeal to the attorney general, John Ashcroft, who was suffering from pancreatitis at a Washington hospital’s intensive care unit.

Lawyers on both sides of the ongoing civil cases said the fact that, at least for a time, top lawyers at the Justice Department doubted the legality of the so-called Terrorist Surveillance Program had no formal relevance to the courts’ ultimate conclusions on the legality of the program. However, several attorneys said the attention to the deep rifts within the government about the program’s lawfulness could make judges reluctant to toss out the legal challenges without a trial or formal discovery, as the Bush administration has urged.

“Anything that implies that there was a tremendous amount of internal dissension about whether or not the president was breaking the law by doing this is very helpful,” an attorney with the Center of Constitutional Rights in Manhattan, Shayana Kadidal, said. “Stories like this make it much more likely that judges looking at this stuff will put an end to it.”

“Atmospherically, it definitely underscores what we’ve been saying all along,” a lawyer pursuing an American Civil Liberties Union suit over the issue, Jameel Jaffer, said. “I think it’s quite extraordinary that the president would ignore the fact that his own attorneys determined the program was unlawful.”

During a press conference yesterday, President Bush declined to say whether he ordered the unusual hospital visit in which his chief of staff, Andrew Card, and the White House counsel who is now attorney general, Alberto Gonzales, tried unsuccessfully to sway Mr. Ashcroft.

“There’s a lot of speculation about what happened and what didn’t happen,” Mr. Bush said. “I’m not going to talk about it. It’s a very sensitive program.”

Mr. Ashcroft is now a lobbyist in Washington. An aide said the former attorney general was not commenting on Mr. Comey’s account.

White House officials have confirmed the existence of a program that involved the interception of phone calls and other communications between persons in America and those abroad thought to have connections to Al Qaeda.

Through a spokesman, Mr. Gonzales said yesterday that he stood by earlier congressional testimony in which he said there was no serious disagreement about the Terrorist Surveillance Program acknowledged by the White House. However, the spokesman, Brian Roehrkasse, said there have been disagreements about “other intelligence activities” and that the Justice Department informed Congress about those differences of opinion.

Some of the surveillance efforts reportedly involved telephone companies, such as AT&T and Verizon, that are facing suits from customers who contend their calls were intercepted illegally by the government with help from the communications firms.

Under orders from a federal judicial panel, nearly 50 lawsuits relating to the surveillance are being managed by Judge Vaughn Walker in San Francisco. Last year, he rejected the government’s arguments that one of the lead cases should be dismissed because it would inevitably disclose state secrets. He said the White House had already confirmed the general outlines of the program. In August, the 9th Circuit Court of Appeals is expected to hear appeals challenging Judge Walker’s decision.

In a separate case last year, Judge Anna Taylor of Detroit ruled that the surveillance program was unconstitutional. However, her order to stop the program was stayed by the 6th Circuit. A panel of that court heard arguments about the program in January and is expected to rule soon.

“If they are acting as judges as opposed to political spin analyzers, they should make their own decision as to whether the president had the power under the Constitution,” a former lawyer for the National Security Council, Bryan Cunningham, said. “If he did, it doesn’t matter if some at the Justice Department disagreed. … If he didn’t have the power, it doesn’t matter if everyone in government said that he did.”

As he testified Tuesday, Mr. Comey declined to identify the program that led to the bedside meeting with Mr. Ashcroft, but senators said it was the much-debated terrorist surveillance plan.

Mr. Comey also stopped just short of calling the program illegal, though at one point he answered in the affirmative to a question about whether he and Mr. Ashcroft considered the White House policy “wrong ” and “against the law.”

The substance of the 2004 conflict between the Justice Department and the White House was reported last year by the New York Times. However, that report, based on unnamed sources, lacked the on-the-record confirmation and some of the rhetorical flourish that Mr. Comey offered Tuesday.