Congress is expected to hold hearings next month on whether President Bush has the power to order domestic eavesdropping on Americans without a court order. Finding the correct balance between defending the country from those who would do it harm and protecting civil liberties is an enduring theme throughout American history.

In the current debate, President Bush defends his use of the National Security Agency to monitor international phone calls and e-mails of Americans suspected of having links with terrorists.

The president has bypassed a 1978 law that requires the government to get a warrant from a special surveillance court before it can eavesdrop on U.S. citizens and resident aliens.

Mr. Bush says the domestic spying program is an essential weapon in the war on terror.

President Bush

"The enemy still wants to hurt us and it seems like to me that if somebody is talking to al-Qaida, we want to know why," he said.

Two civil rights groups have filed federal lawsuits in an effort to stop the domestic spying program, charging that the president has exceeded his constitutional authority.

Anthony Romero is the executive director of the American Civil Liberties Union, one of the groups that filed a lawsuit.

"This historic lawsuit responds to an unprecedented seizure of power by the executive branch," he said.  "To be clear, the ACLU believes that the National Security Agency spying program is both unconstitutional and illegal."

The debate over how far a president can go during wartime to protect the country is as old as the American Republic.

"We have seen this arise during the Civil War when Abraham Lincoln suspended many of our basic rights," said Larry Sabato, who directs the Center for Politics at the University of Virginia. "We saw it happen in World War I when the same things occurred under President Woodrow Wilson, World War II with Franklin Roosevelt, the Cold War with a series of both Democratic and Republican presidents."

Over the years, the federal courts have evolved as the primary check on executive power.

Carl Stern is a legal expert at George Washington University and a frequent guest on VOA's Talk to America program.

"The United States is governed by a constitution, which is the supreme law of the land," he said. "And the Constitution does two things. It sets out our form of government and it imposes limits on what government officials can do. In the long run, it is up to the Supreme Court to decide when officials have exceeded those limits and hence, the Supreme Court has a principal role in deciding how government can affect the lives of ordinary Americans."

Larry Sabato

Political analyst Larry Sabato predicts more debate but no resolution of the issue in the year ahead.

"This is an enduring controversy," he said. "We are going to see the same arguments made in 2006 that have been made repeatedly in American history. I doubt we come any closer to resolving the ultimate dispute because, in a sense, it is not resolvable. You have to reach some kind of reasonable balance between individual liberty and security. It is not easy to do."

A recent Washington Post-ABC News poll found that 51 percent of those surveyed supported the president's domestic spying program to root out terrorists while 47 percent were opposed.