MB Civic

By SCOTT SHANE

WASHINGTON, July 19 — Legal experts squared off before Congress on Wednesday about the National Security Agency’s domestic surveillance program, offering radically different views on whether changes in the law are needed to allow eavesdropping on terror suspects without violating Americans’ privacy.

Judge Richard A. Posner, an author on intelligence, told the House Intelligence Committee that the requirement for court warrants under the Foreign Intelligence Surveillance Act was “obsolete.”

To get a warrant from the secret court that oversees such eavesdropping, said Judge Posner, who sits on the United States Court of Appeals for the Seventh Circuit, the government must already know who the terrorists are. “The challenge for intelligence is not to track down known terrorists,” he said. “It’s to find out who the terrorists are.”

Michael S. Greco, president of the American Bar Association, sharply disagreed, saying the FISA statute and its requirements for warrants remained a crucial protection for civil liberties. The courts and Congress must have a role in governing intelligence wiretaps, he said.

“The awesome power to penetrate Americans’ most private communications is too great a power to be held solely by the executive branch of government,” Mr. Greco said.

Mr. Greco, along with other witnesses, urged Congress not to act until the Bush administration provided more information on its electronic surveillance programs and how they might be hampered by existing laws. The Intelligence Committee chairman, Representative Peter Hoekstra, Republican of Michigan, said administration officials would be asked to clarify such problems at a later hearing.

Wednesday’s hearing was the latest sign that Congress was reasserting its role in overseeing sensitive counterterrorist surveillance programs, despite President Bush’s argument that he has the inherent constitutional authority to order eavesdropping without court approval.

Several bills related to the security agency are pending in the House and Senate. One, proposed by Senator Arlen Specter, Republican of Pennsylvania and chairman of the Judiciary Committee, would ask the FISA court to rule on the constitutionality of the eavesdropping program. That idea has the support of the White House, but has been criticized as a surrender to the administration, and its fate is uncertain.

Under the program, the agency intercepts international telephone calls and e-mail messages of Americans and others in the United States who are believed to have links to Al Qaeda. But the agency does not first get warrants from the FISA court, as the law ordinarily requires for eavesdropping inside the country.

Administration officials have suggested that the warrant requirement is too cumbersome to allow the rapid pursuit of possible terrorists. But some lawmakers who have been briefed on the secret program say there is no reason the program cannot operate in compliance with the FISA statute.

Even the administration’s critics acknowledge that procedures to get warrants may need to be updated. James X. Dempsey, of the Center for Democracy and Technology, a civil liberties group, called it “ridiculous in the age of BlackBerrys’’ to be applying for warrants on paper.

The discussion on Wednesday underscored the uncertainty, even among experts, about the security agency’s practices at a time when the Internet is reshaping communications. Representative Heather Wilson, Republican of New Mexico, asked whether the agency needed a warrant to intercept an Internet phone call from Sudan to Afghanistan if the call passed through the United States.

“I’m not sure that’s a resolved issue,” replied Kim Taipale, executive director of the Center for Advanced Studies in Science and Technology Policy. Committee Democrats took note of Attorney General Alberto R. Gonzales’s revelation on Tuesday that the president personally blocked an internal Justice Department investigation of the lawyers who approved the eavesdropping program.

Representative C. A. Dutch Ruppersberger, a Maryland Democrat whose district includes the security agency’s headquarters, said the president’s action suggested why the courts and Congress needed to oversee eavesdropping.

One goal of any legislation, Mr. Ruppersberger said, should be to clarify the rules so that agency officers “will have no insecurities about what’s legal and what’s illegal.”