As President Bush vowed yesterday to "lead the world to victory over terrorism," lawmakers, activists and scholars debated how far the government should go in curbing civil liberties to avoid a repeat of this week's horrific attack on the United States.

The Senate, enraged by the terrorist mayhem in New York and Washington, last night approved legislation that would make it easier for the FBI to get warrants for electronic surveillance of computer transmissions.

Individual rights champions as disparate as conservative Paul Weyrich, the American Civil Liberties Union and the libertarian Cato Institute have cautioned Congress and the White House against action that might impinge on the very rights they are seeking to protect. But key lawmakers in both parties acknowledge that some erosion of civil liberties may be inevitable.

"We're in a new world where we have to rebalance freedom and security," House Democratic Leader Richard A. Gephardt (D-Mo.) said yesterday. "We can't take away people's civil liberties . . . but we're not going to have all the openness and freedom we have had."

In past crises during this century -- from the anarchist-communist scares of 1917-18 to the Oklahoma City bombing in 1995 -- Congress has responded by enacting major expansions of state police powers over the objections of civil libertarians. During World War I, Congress passed the Espionage and Sedition acts, which were used to arrest more than 1,500 people, many of whom were deported.

In 1996, after Oklahoma City, Congress enacted anti-terrorism and immigration control legislation that severely curtailed the ability of defendants in death penalty cases to appeal their sentences and that allowed federal officials to use secret evidence in deportation cases.

Last night, the House moved toward passage of a $20 billion emergency spending bill to finance the preliminary response to the devastation in Lower Manhattan and the damage to the Pentagon. The bill would also support law enforcement agencies' efforts to counter and investigate domestic or international terrorism.

Sen. Jon Kyl (R-Ariz.), who sponsored the amendments in the Senate, complained that in the past, civil libertarians have blocked legislation essential to frustrating terrorists. He vowed to press for other legislation to make it easier to get court authorization for searches and surveillance in domestic terrorism cases and a series of reforms called for by the National Commission on Terrorism.

"We must determine just what we need to do to increase our intelligence-gathering activities so that we can stop or at least have advance warnings about attacks on American soil," Kyl said.

Congressional leaders have yet to decide how far to go in rewriting the federal criminal code to clamp down on suspected terrorists. Rep. C. Saxby Chambliss (R-Ga.), a senior member of the intelligence committee and head of a task force on terrorism and homeland security, met yesterday with House Speaker J. Dennis Hastert (R-Ill.) and other leaders to begin mapping out a strategy.

Senate Minority Leader Trent Lott (R-Miss.) took a hard line earlier this week, telling reporters that "when you're in this type of conflict, when you're at war, civil liberties are treated differently."

"We've been having an academic discussion and holding our breath in this area for several years," Lott added. "We can't do that anymore."

But Congress is divided on how best to proceed, and many on both sides of the aisle are counseling caution. "Frisking everyone on the planet to find the one person with the weapon is a high-cost, low-yield way to go," said Rep. Christopher Cox (R-Calif.) "That's a fair analogy to searching through everyone's e-mail. Not only do such schemes threaten civil liberties, they are such scattershot approaches that they are bound to fail."

The Lawyers' Committee for Civil Rights Under Law is meeting in San Francisco on Friday to discuss the risks of repressive steps taken in the name of safety and plan a response if needed.

The Bush administration already has moved on several fronts this week to tighten security in the aftermath of the mass killings. The Federal Aviation Administration has imposed tough new regulations at commercial airports that will add hours to the average flight and has agreed to put armed marshals on many flights to discourage future hijackings.

Federal authorities have also tightened security at federal buildings and national monuments, closed more than 50 embassies around the world, and created gridlock at crossings along the 2,000-mile U.S.-Mexico border by requiring inspections of practically every vehicle.

During a luncheon yesterday with Washington Post reporters and editors, Gephardt said that "people will be terribly inconvenienced." He added, "It's a very tough political transaction that we're going to have to make. . . . We can't go on with business as usual in the way we conduct American life."

Many have described this week's tragedy as a turning point in the nation's history -- an abrupt end to Americans' sense of safety and invincibility. Yet at the core of the unfolding debate over responding to the terrorist attacks is how willing Americans are to accept fundamental changes in their society.

Some point to Israel's response to terrorism -- with armed soldiers on every other block, excruciatingly tight security at airports and in government buildings, racial profiling, and lax standards for obtaining and using evidence against defendants -- as unacceptable to them. "We ought to be aware of what the Israelis are doing and whether that's the sort of thing we would do," said William A. Niskanen of the Cato Institute. Niskanen said he argued against Congress moving ahead with a series of actions that might curtail civil liberties, "But I fully expect that to happen."

Ibrahim Hooper, communications director of the Council on American-Islamic Relations, said he feared that with anti-Muslim feelings running high in the country because of the highjackings, Congress might respond with action that would diminish the rights of Muslim Americans.

"We're getting reports every day of beatings, harassment, shots fired at mosques," Hooper said. "We know people's emotions run high, but our rights are not subject to circumstances, but are inalienable."