WASHINGTON — Five former judges on the nation's most secretive court, including one who resigned in apparent protest over President Bush's domestic eavesdropping, urged Congress on Tuesday to give the court a formal role in overseeing the surveillance program.

In a rare glimpse into the inner workings of the secretive court, known as the Foreign Intelligence Surveillance Court, several former judges who served on the panel also voiced skepticism at a Senate hearing about the president's constitutional authority to order wiretapping on Americans without a court order. They also suggested that the program could imperil criminal prosecutions that grew out of the wiretaps.

Judge Harold A. Baker, a sitting federal judge in Illinois who served on the intelligence court until last year, said the president was bound by the law "like everyone else." If a law like the Foreign Intelligence Surveillance Act is duly enacted by Congress and considered constitutional, Judge Baker said, "the president ignores it at the president's peril."

Judge Baker and three other judges who served on the intelligence court testified at a Senate Judiciary Committee hearing in support of a proposal by Senator Arlen Specter, Republican of Pennsylvania, to give the court formal oversight of the National Security Agency's eavesdropping program. Committee members also heard parts of a letter in support of the proposal from a fifth judge, James Robertson, who left the court last December, days  after the eavesdropping program was disclosed (picture: Beverly Rezneck/Polaris).

The intelligence court, created by Congress in 1978, meets in a tightly guarded, windowless office at the Justice Department. The court produces no public findings except for a single tally to Congress each year on the number of warrants it has issued — more than 1,600 in 2004. Even its roster of judges serving seven-year terms was, for a time, considered secret.

But Mr. Bush's decision effectively to bypass the court in permitting eavesdropping without warrants has raised the court's profile. That was underscored by the appearance on Tuesday of the four former FISA judges: Judge Baker; Judge Stanley S. Brotman, who left the panel in 2004; Judge John F. Keenan, who left in 2001; and Judge William H. Stafford Jr., who left in 2003. All four sit on the federal judiciary.

At a hearing lasting more than three hours, the former FISA judges discussed in detail their views on the standards of proof required by the court, its relations with the Justice Department, and the constitutional, balance-of-power issues at the heart of the debate over the N.S.A. program. The agency monitored the international communications of people inside the United States believed to be linked to Al Qaeda.

The public broadcasting of the court's business struck some court watchers as extraordinary. "This is unprecedented," said Magistrate Judge Allan Kornblum, who supervised Justice Department wiretap applications to the court for many years and testified alongside the four former judges.

But the most pointed testimony may have come from a man who was not at the hearing: Judge Robertson.

A sitting federal judge in Washington, Judge Robertson resigned from the intelligence court just days after the N.S.A. program was disclosed.

Colleagues say he resigned in frustration over the fact that none of the court's 11 judges, except for the presiding judge, were briefed on the program or knew of its existence. But Judge Robertson has remained silent, declining all requests for interviews, and his comments entered into The Congressional Record on Tuesday represented his first public remarks on the controversy.

In a March 23 letter in response to a query from Mr. Specter, the judge said he supported Mr. Specter's proposal "to give approval authority over the administration's electronic surveillance program" to the court.

The Bush administration, in its continued defense of the program, maintains that no change in the law is needed because the president has the inherent constitutional authority to order wiretaps without warrants in defense of the country.

Mr. Specter's proposal seeks to give the intelligence court a role in ruling on the legitimacy of the program. A competing proposal by Senator Mike DeWine, Republican of Ohio, would allow the president to authorize wiretaps for 45 days without Congressional oversight or judicial approval.

Judge Robertson made clear that he believed the FISA court should review the surveillance program. "Seeking judicial approval for government activities that implicate constitutional protections is, of course, the American way," he wrote.

But Judge Robertson argued that the court should not conduct a "general review" of the surveillance operation, as Mr. Specter proposed. Instead, he said the court should rule on individual warrant applications for eavesdropping under the program lasting 45 or 90 days.

Acknowledging the need for secrecy surrounding such a program, he said the FISA court was "best situated" for the task. "Its judges are independent, appropriately cleared, experienced in intelligence matters, and have a perfect security record," Judge Robertson said.

He did not weigh in on the ultimate question of whether he considered the N.S.A. program illegal. The judges at the committee hearing avoided that politically charged issue despite persistent questioning from Democrats, even as the judges raised concerns about how the program was put into effect.

Judge Baker said he felt most comfortable talking about possible changes to strengthen the foreign intelligence law. "Whether something's legal or illegal goes beyond that," he said, "and that's why I'm shying away from answering that."