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The National Security Agency has been secretly granted legal authority to operate a massive domestic eavesdropping system that vacuums up Americans' phone calls and Internet communications, newly leaked documents show.

A pair of classified government documents (No. 1 and No. 2) signed by Attorney General Eric Holder and posted by the Guardian on Thursday show that NSA analysts are able to listen to Americans' intercepted phone calls without asking a judge for a warrant first.

That appears to be at odds with what President Obama said earlier this week in defense of the NSA's surveillance efforts. "I can say unequivocally is that if you are a U.S. person, the NSA cannot listen to your telephone calls and the NSA cannot target your e-mails," Obama said.

The new documents indicate, however, that NSA, CIA, and FBI analysts are granted broad access to data vacuumed up by the world's most powerful intelligence agency -- but are supposed to follow certain "targeting" and "minimization" procedures to limit the number of Americans who become individual targets of warrantless surveillance.

CNET has not verified the authenticity of the documents. The Justice Department did not respond to a request for comment this afternoon.

Analysts are expected to exercise "reasonable judgment" in determining which data to use, according to the documents, and "inadvertently acquired communications of or concerning a United States person may be retained no longer than five years." The documents also refer to "content repositories" that contain records of devices' "previous Internet activity," and say the NSA keeps records of Americans' "electronic communications accounts/addresses/identifiers" in an apparent effort to avoid targeting them in future eavesdropping efforts.

The Holder procedures were blessed in advance by the secret Foreign Intelligence Surveillance Court, the Guardian reported, meaning that the judges would have issued a general order that authorizes the NSA to engage in warrantless surveillance as long as it's primarily aimed at foreign targets, subject to some limited judicial oversight.

Today's disclosure jibes with what Edward Snowden, the former NSA contractor who leaked top-secret documents, alleged in an online chat earlier this week. Snowden said, referring to the contents of e-mail and phone calls, that "Americans' communications are collected and viewed on a daily basis on the certification of an analyst rather than a warrant."

On Sunday, Director of National Intelligence James Clapper released a carefully-worded statement in response to a CNET article and other reports questioning when intelligence analysts can listen to domestic phone calls. Clapper said: "The statement that a single analyst can eavesdrop on domestic communications without proper legal authorization is incorrect and was not briefed to Congress."

Clapper's statement was viewed as a denial, but it wasn't. Today's disclosures reveal why: Because the Justice Department granted intelligence analysts "proper legal authorization" in advance through the Holder regulations.

"The DNI has a history of playing games with wording, using terms with carefully obscured meanings to leave an impression different from the truth," Kurt Opsahl, a senior staff attorney at the Electronic Frontier Foundation who has litigated domestic surveillance cases, told CNET earlier this week.

Jameel Jaffer, the American Civil Liberties Union's deputy legal director, said in a statement today that:

After Congress enacted the FISA Amendments Act in 2008, we worried that the NSA would use the new authority to conduct warrantless surveillance of Americans' telephone calls and emails. These documents confirm many of our worst fears. The "targeting" procedures indicate that the NSA is engaged in broad surveillance of Americans' international communications. The "minimization" procedures that supposedly protect Americans' constitutional rights turn out to be far weaker than we imagined they could be. For example, the NSA claims the authority to collect and disseminate attorney-client communications -- and even, in some circumstances, to turn them over to Justice Department prosecutors. The government also claims the authority to retain Americans' purely domestic communications in certain situations.

The documents suggest there are some significant loopholes in domestic surveillance: if an NSA analyst reviews an intercepted communication and finds "evidence of a crime that has been, is being, or is about to be committed," it can be forwarded to the FBI or other federal law enforcement agencies.

Another loophole is "a serious harm to life or property" -- which could sweep in intellectual property -- and "enciphered" data. Communications that contain "enciphered" data, which would likely include PGP but also could mean encrypted Web connections using SSL, may be kept indefinitely.

Earlier reports have indicated that the NSA has the ability to record nearly all domestic and international phone calls -- in case an analyst needed to access the recordings in the future. A Wired magazine article last year disclosed that the NSA has established "listening posts" that allow the agency to collect and sift through billions of phone calls through a massive new data center in Utah, "whether they originate within the country or overseas." That includes not just metadata, but also the contents of the communications.

Documents that came to light in a different EFF lawsuit provide some insight into how the spy agency vacuums up data from telecommunications companies. Mark Klein, who worked as an AT&T technician for more than 22 years, disclosed in 2006 (PDF) that he witnessed domestic voice and Internet traffic being surreptitiously "diverted" through a "splitter cabinet" to secure room 641A in one of the company's San Francisco facilities. The room was accessible only to NSA-cleared technicians.

AT&T and other telecommunications companies that allow the NSA to tap into their fiber links receive absolute immunity from civil liability or criminal prosecution, thanks to a law that Congress enacted in 2008 and renewed in 2012. It's a series of amendments to the Foreign Intelligence Surveillance Act, also known as the FISA Amendments Act.

Section 702 of the FAA says surveillance may be authorized by the attorney general and director of national intelligence without prior approval by the secret Foreign Intelligence Surveillance Court, as long as minimization requirements and general procedures blessed by the court are followed.

Last updated at 5:45 p.m. PT