Civil liberties advocates on Friday asked a federal court in New York to end the National Security Agency counterterrorism program that collects data on billions of phone calls by Americans, arguing that it violates the Constitution and was not authorized by Congress.

The case was brought by the American Civil Liberties Union after the publication in June of a court order to Verizon Business Network Services that showed the phone company was required to turn over to the NSA all call detail records of its customers, including the length and time of calls but not the content.

The sweeping nature of that collection, which was placed under court supervision in secret in May 2006, set off a furious public discussion over whether the agency's efforts to thwart terrorist attacks have overstepped the legal and common-sense boundaries of privacy.