Story highlights Policy change in 2010 permits NSA social mapping program

Latest disclosure in The New York Times comes from documents provided by Edward Snowden

NSA repeats it does not listen to calls or read e-mails without court permission

Legal expert: Newly disclosed system "tells an extraordinary amount about who you are"

In addition to phone records and email logs, the National Security Agency uses Facebook and other social media profiles to create maps of social connections -- including those of American citizens.

The revelation was disclosed by the New York Times on Sunday, using documents provided to the newspaper by former government contractor Edward Snowden.

"We assume as Americans that if somebody in the government is looking at your information, it's because they have a reason, because you're suspected of a crime," Karen Greenberg, director of the Center on National Security at Fordham Law School, told CNN.

But the documents do not specify how many Americans' social connections have been analyzed, or whether any have been implicated in wrongdoing.

Change in policy

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Photos: Photos: NSA leaker Edward Snowden Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – National Security Agency leaker Edward Snowden poses with German Green party parliamentarian Hans-Christian Stroebele in Moscow on October 31. Stroebele returned from the meeting with a letter from Snowden to German authorities, which was distributed to the media. In it, Snowden said he is confident that with international support, the United States would abandon its efforts to "treat dissent as defection" and "criminalize political speech with felony charges." Hide Caption 1 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Snowden's refugee document granted by Russia is seen during a news conference in Moscow on August 1. Snowden slipped quietly out of the airport after securing temporary asylum in Russia , ending more than a month in limbo. Hide Caption 2 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Sen. Charles Schumer, D-New York, leaves a last-minute news conference at the U.S. Capitol after Russia announced that it would grant Snowden temporary asylum on August 1. "Russia has stabbed us in the back, and each day that Mr. Snowden is allowed to roam free is another twist of the knife," he said. Hide Caption 3 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Snowden's father, Lon Snowden, who has adamantly supported his son, talks to reporters in Washington on Tuesday, July 30. He has urged his son to remain in Russia "until we have assurances that he would receive a fair trial." Hide Caption 4 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Demonstrators in Berlin hold a protest march on Saturday, July 27, in support of Snowden and WikiLeaks document provider Bradley Manning. Both men have been portrayed as traitors and whistle-blowers. Manning was acquitted on July 30 on the most serious charge of aiding the enemy, but he was convicted on several other counts and likely faces a lengthy term in a military prison. Hide Caption 5 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Russian lawyer Anatoly Kucherena, center, speaks with journalists at the Sheremetyevo International Airport in Moscow after meeting with Snowden on Wednesday, July 24. Kucherena said he was in daily contact with Russian authorities about securing permission for Snowden to leave the airport. Hide Caption 6 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Snowden meets with human rights activists and lawyers on July 12 in a transit zone of the Russian airport. It was his first public appearance since he left Hong Kong on June 23. He announced that he was seeking refuge Russia while awaiting safe passage to Latin America, where he has been offered asylum. Hide Caption 7 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Russian President Vladimir Putin attends a meeting in Prokhorovka on July 12. Russian officials said Snowden abandoned his effort to seek asylum in the country after Putin warned that he would have to stop leaking information about U.S. surveillance programs if he wanted to stay. Hide Caption 8 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – A woman burns American flags during a protest in support of Bolivian President Evo Morales in front of the U.S. embassy in Mexico City on July 4. Leftist Latin American leaders and activists were fuming after some European nations temporarily refused Morales' plane access to their airspace amid suspicions Snowden was aboard. Hide Caption 9 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Bolivian President Evo Morales holds a news conference at the Vienna International Airport on July 3. He angrily denied any wrongdoing after his plane was diverted to Vienna and said that Bolivia is willing to give asylum to Snowden , as "fair protest" after four European countries restricted his plane from flying back from Moscow to La Paz. Hide Caption 10 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Umbrellas with slogans are lined up before a protest march to the U.S. consulate in Hong Kong on June 15. Snowden was hiding in Hong Kong, where he arrived on May 20 before blowing the lid off the NSA surveillance operation. Hide Caption 11 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Protesters in Hong Kong shout slogans in support of Snowden on June 13. The NSA leaker vowed to fight any bid to extradite him from Hong Kong. Hide Caption 12 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Graffiti sympathetic to Snowden is stenciled on the sidewalk in San Francisco on June 11. Hide Caption 13 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – An American flag flutters in front of the U.S. consulate in Hong Kong on June 10. Hide Caption 14 of 15 Photos: Photos: NSA leaker Edward Snowden NSA leaker Edward Snowden – Snowden outs himself on June 9 in the British newspaper The Guardian, which published details of his revelations about the NSA electronic surveillance programs. "I have no intention of hiding who I am because I know I have done nothing wrong," he said in a video interview. Hide Caption 15 of 15

The surveillance began after a policy change in November 2010.

Prior to then, the "chaining" of a foreign person's contacts had to stop when it reached an American citizen or legal resident.

The policy change was intended to help the NSA "discover and track" connections from a foreign intelligence subject to an American citizen, the leaked documents show.

It allows NSA analysts to use social media, geo-location information, insurance and tax records, plus other public and private sources to enhance their analysis of phone and email records, The Times reported Sunday

The "metadata" from phone and email records in the database include details such as who a person called or e-mailed.

A PowerPoint slide provided to the newspaper by Snowden shows how analysts use software to create diagrams of where a person was at certain times, their traveling companions, their social networks and email correspondents.

Defending the practice

President Barack Obama has ordered a review of NSA's data collection practices because of Snowden's leaks. But the president has defended the use of such methods to gather intelligence on terrorists and other threats.

In response to the latest disclosure, the NSA again emphasized it does not listen to phone calls or read emails of Americans without obtaining a court order.

But the newly disclosed system "tells an extraordinary amount about who you are ... who your closest allies and friends and colleagues are," Greenberg said.

"To pretend that you have to read the information to be going into what a person is doing is making a false distinction."