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The National Security Agency is vacuuming up records of millions of phone calls made inside the United States, a top secret court order reveals.

A top secret order that was released this afternoon requires Verizon to hand over to the NSA "on an ongoing daily basis" information about all domestic and overseas calls -- "including local telephone calls."

The FBI obtained the secret order, which was disclosed by The Guardian newspaper, from the secret Foreign Intelligence Surveillance Court, which meets behind closed doors and whose proceedings rarely become public. It was signed by FISC Judge Roger Vinson, who normally serves as a federal judge in Florida.

Vinson's order relies on Section 215 of the Patriot Act, 50 USC 1861, better known as the "business records" portion. It allows FBI agents to obtain any "tangible thing," including "books, records, papers, documents, and other items," a broad term that includes dumps from private-sector computer databases with limited judicial oversight.

The American Civil Liberties Union criticized the order as "beyond Orwellian," and the Progressive Change Campaign Committee launched a petition to Congress.

"From a civil liberties perspective, the program could hardly be any more alarming. It's a program in which millions of innocent people have been put under the constant surveillance of government agents," ACLU Deputy Legal Director Jameel Jaffer said in a statement. "It's analogous to the FBI stationing an agent outside every home in the country to track who goes in and who comes out."

The Justice Department's secret interpretation of Section 215 was what alarmed Sens. Ron Wyden (D-Oregon) and Mark Udall (D-Colorado) when the Patriot Act was up for renewal two years ago. Both senators served on the intelligence committee and were briefed on the NSA's activities.

"I believe that when more of my colleagues and the American public come to understand how the Patriot Act has actually been interpreted in secret, they will insist on significant reforms too," Wyden said at the time.

Udall told CNET this evening: "While I cannot corroborate the details of this particular report, this sort of widescale surveillance should concern all of us and is the kind of government overreach I've said Americans would find shocking. As a member of the Senate Intelligence Committee, it's why I will keep fighting for transparency and appropriate checks on the surveillance of Americans."

There have been other hints that the NSA's massive databases were being fed Americans' confidential telephone records -- which can then be perused by the FBI for domestic criminal investigations.

Former FBI counterterrorism agent Tim Clemente told CNN last month that, in national security investigations, the bureau can access records of a previously-made telephone call. "All of that stuff is being captured as we speak whether we know it or like it or not," he said. Clemente added in an appearance the next day that, thanks to the "intelligence community" -- a likely reference to the NSA -- "there's a way to look at digital communications in the past."

Vinson's top secret order dated April 25, which expires July 19, does not require Verizon to divulge the contents of communications or the names of its customers. It does force the company to hand over originating and terminating telephone number, the IMSI, and IMEI numbers for mobile phones, trunk identifiers, the time of the call, and other information. The New York Times this evening confirmed that the order was authentic.

The Justice Department previously confirmed that Section 215 "has been used to obtain driver's license records, hotel records, car rental records, apartment leasing records, credit card records, and the like." Todd Hinnen, acting assistant attorney general for national security, told a House of Representatives committee that such directives were constitutional because they are "not a 'search' within the meaning of the Fourth Amendment." (The Fourth Amendment, of course, prohibits "unreasonable" searches and seizures.)

FBI Director Robert Mueller hinted during a 2011 congressional hearing that there was a secret legal memorandum prepared by the Justice Department's Office of Legal Counsel that authorized a broader use of Section 215 than is publicly known.

Wyden, who was present at that hearing, told Mueller that he was "increasingly troubled" that intelligence agencies are "relying on a secret interpretation" of the Patriot Act. "I believe that the American people would be absolutely stunned," Wyden said, if they knew what was actually going on.

Section 215 says that an order must be approved by the secret FISA court if the FBI shows the data "sought are relevant to an authorized investigation" dealing with terrorism -- a requirement that provides little privacy protection in practice.

Another hint about overly broad use of Section 215 came from former Sen. Russ Feingold, a Democrat who has since lost his seat. He said in a February 2010 floor speech that:

Section 215 has been misused. I cannot elaborate, but I believe that the public deserves some information about this. I and others have also pressed the administration to declassify some basic information about the use of section 215, and it has declined... We must find a way to have an open and honest debate about the nature of these government powers, while still protecting national security secrets, and under current conditions that simply isn't possible... Lawyers in the Office of Legal Counsel looked for every possible loophole in statutory language to justify what I believe were clearly illegal wiretapping and interrogation programs. That should also teach us that we must be extraordinarily careful in how we draft these laws: We must say exactly what we mean and leave no room for reinterpretation.

It's not clear if this is the extent of the Justice Department's secret use of Section 215, or if other confidential customer data such as the locations of cell phones is being vacuumed up by the NSA as well. The FBI did not immediately respond to a request for comment.

This disclosure calls into question comments made by NSA director Keith Alexander, who told Congress last year (video) that "we're not authorized" to obtain "information involving American citizens."

It also didn't come as a great surprise to government-surveillance watchers. In 2006, USA Today reported that the NSA "has been secretly collecting the phone call records of tens of millions of Americans, using data provided by AT&T, Verizon and BellSouth."

One person interviewed for that article called the program, which began in late 2001, "the largest database ever assembled in the world." Only Qwest reportedly refused to participate. Its chief executive, Joe Nacchio, was subsequently convicted on unrelated charges involving illegal stock sales.

A followup article reported that Verizon provided a statement denying entering "into an arrangement to provide the NSA with data from its customers' domestic calls." But the carefully-worded denial left open the possibility that metadata was turned over.

Last updated at 12:30a.m. PT June 6.