"The NSA has trillions of telephone calls and emails in their databases that they’ve collected over the last several years," Greenwald told ABC News on Sunday evening. "And what these programs are, are very simple screens, like the ones that supermarket clerks or shipping and receiving clerks use, where all an analyst has to do is enter an email address or an IP address, and it does two things. It searches that database and lets them listen to the calls or read the emails of everything that the NSA has stored, or look at the browsing histories or Google search terms that you’ve entered, and it also alerts them to any further activity that people connected to that email address or that IP address do in the future."
"It’s an incredibly powerful and invasive tool, exactly of the type Mr. [Edward] Snowden described," Greenwald added. He explained that these programs allow analysts to search through data with little court approval or supervision.
"These systems allow analysts to listen to whatever emails they want, whatever telephone calls, browsing histories, Microsoft Word documents," Greenwald said.
The Republican senator Saxby Chambliss backed the NSA program, claiming that Greenwald exaggerated the surveillance coverage under the program.
"I have been assured of is that there is no capability at NSA for anyone without a court order to listen to any telephone conversation or to monitor any e-mail," Chambliss said, after he met high and low level NSA officials.
"In fact, we don’t monitor emails. That’s what kind of assures me is that what the reporting is not correct. Because no emails are monitored now," Chambliss claimed. 'They used to be, but that stopped two or three years ago. So I feel confident that there may have been some abuse, but if it was it was pure accidental."
Former federal judge James Robertson, who used to grant surveillance orders, said he was shocked to hear of changes to allow broader authorization of NSA programs - such as the monitoring of US phone records.
"What FISA does is not adjudication, but approval," Robertson said, speaking as a witness during the first public hearings into the Snowden revelations. "This works just fine when it deals with individual applications for warrants, but the 2008 amendment has turned the FISA court into an administrative agency making rules for others to follow."
Glenn Greenwald will testify before a Congressional committee on Wednesday, along with NSA officials who have previously downplayed Snowden’s claims about the agency’s easy-access data.
PRISM is a mass electronic surveillance data program operated by the NSA since 2007 in collaboration with the CIA. Edward Snowden, former CIA employee and former NSA analyst, leaked information about the program to the media, warning of a far greater extent of mass data collection than the public knew existed. The disclosures were published by The Guardian and The Washington Post on June 6.
Snowden later leaked further information to the Guardian reporter Glenn Greenwald. The whistleblower also shared information regarding Germany’s cooperation with US intelligence, which reportedly combs through half a billion German phone calls, emails, and text messages on a daily basis.
 RT, the Huffington Post