No technologist interviewed for this story believes the NSA simply vacuums up every piece of data from all tech companies. Despite advances in storage and transmission speeds, that would still be technically challenging and probably unnecessary. Why recreate Google when the agency can just ask Google for the data it wants?
Early versions of the Prism story asserted that the tech giants involved voluntarily participated in the program and were unaware of the queries made by agents. But most of the firms said they'd never heard of Prism, and that they don't allow unfiltered access to data. Both can be true, Soltani said.
"The NSA doesn't want companies to know the targets of their investigations, so I think they issue broad directives to the companies," he said. For example, rather than saying, "Give us all Bob Sullivan's emails from last month," the NSA hides its true intentions by saying "Give us all email written by someone with the initials B.S. last month."
It's also possible that Prism is an internal code name the NSA uses, and firms that installed locked mailboxes had no idea they were participating in Prism.
"Assuming everyone is telling the truth, this is how I think it works," Soltani said. "And while we may disagree, there's certainly a way to imagine Prism is perfectly legal, based on the laws Congress has passed."
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There's plenty of precedent for technology companies giving streamlined data access to law enforcement. Last year, the American Civil Liberties Union released a study showing that wireless firms give thousands of location records to local and federal investigators; some even have website portals where the records can be ordered in bulk.
It's uncomfortable seeing such mass surveillance in action, and it might be enough to stir renewed public debate on the topic, but Prism is the logical conclusion of laws Congress has passed and the natural tendency of law enforcement to push the envelope when investigating crimes.
"Prism didn't shock me at all. When I read the FISA Amendment Act ... I see Prism with my eyes," said Chris Soghoian, privacy rights expert with the American Civil Liberties Union.
If companies must act on each data request the government makes, they have the opportunity to step in and object. That might be a weak protection, but it is a protection. And it's a far cry from NSA agents simply rooting around Google at any time for anything.
Soghoian and Soltani are concerned that leaks about Prism have directed attention away from an earlier leak showing the NSA has obtained millions of phone records detailing U.S. users' calls from Verizon. A leaked secret court order indicates Verizon is giving the NSA details about every call placed in the U.S.
"When I look at the Patriot Act, I don't see that. That shocks me. It's terrifying," Soghoian said. "What really matters, the million dollar question, isn't who has direct access to the data. It's the scale and volume of information being shared."
Still, if Prism is as broad-reaching as some have suggested, that's a concern for Soltani.
"The American public had previously, maybe unknowingly, relied on technical and financial barriers to protect them from large scale surveillance by the government," Soltani said. "However, these implicit protections have quickly eroded in recent years as technology industry advances have trickled down to the intelligence agencies, and as a result, changed the delicate balance of power."
The argument we are now having, pitting civil liberties advocates against law enforcement, probably should have happened in 2008, when the FISA law was substantially revised to clear the way for tools like Prism. As the costs associated with massive surveillance and data storage continue to drop, experts warn that it's inevitable that privacy invasions will rise, unless unchecked.
"We need to remember that this is a trend with a firm lower bound — once the cost of surveillance reaches zero we will be left with outdated laws as the only remaining barrier," Soltani said.
—By Bob Sullivan of NBC News