But the ACLU and other groups filing Thursday's lawsuit disagreed.

Author and journalist Chris Hedges, former Middle East bureau chief for the New York Times, said the FISA Amendments Act will make it difficult for journalists, especially those who report on overseas issues, to do their jobs. One of Hedges' sources has already cut off contact for fear that Hedges' communications are wiretapped, he said.

The new law makes the U.S. no different from dictatorial regimes that spy on their citizens, added Hedges, who now writes for the liberal magazine The Nation, which is among the plaintiffs in the ACLU lawsuit.

"The power of this surveillance can essentially shut down the ability of whistleblowers, human-rights activists, dissidents, true-tellers and people with a conscience to rise up and speak against the audacity of those in power," Hedges said. "With that gone, we take a giant step toward fascism."

The ACLU also filed a motion with the U.S. FISA Court, which normally conducts its business in secret, to conduct any hearings it might have on the constitutionality of the FISA Amendments Act to be open to the public. The FISA Court may have to address the constitutionality or the scope of the new law, said Melissa Goodman, an attorney with the ACLU's National Security Project.

"No one, not even members of Congress, seems to truly understand precisely how much power this law gives the government," Goodman said.

In July 2007, the U.S. Court of Appeals for the 6th Circuit threw out a similar lawsuit against the surveillance program brought by the ACLU. The court ruled that the plaintiffs, including academics, lawyers and journalists, didn't have standing to sue the government because they couldn't demonstrate they were targeted by the secret program.

The new lawsuit has a better chance because there's a law outlining the program that can be challenged, ACLU officials said.