One official likened the NSA's collection authority to a van full of sealed boxes that are delivered to the agency. A court order, similar to the one revealed by the Guardian, permits the transfer of custody of the "boxes." But the NSA needs something else, a specific purpose or investigation, in order to open a particular box...Today in his on-line chat, Snowden basically said the same thing.
In the government's eyes, the data is simply moving from one place to another. It does not become, in the government's eyes, relevant or protected in any way unless and until it is subject to analysis. Analysis requires that second order.
And the government insists that the rules allowing the NSA or the FBI to analyze anything relating to U.S. persons or corporations are strict, bright-line, and are regularly scrutinized to ensure that innocents don't get caught up in the mix.
More detail on how direct NSA's accesses are is coming, but in general, the reality is this: if an NSA, FBI, CIA, DIA, etc analyst has access to query raw SIGINT databases, they can enter and get results for anything they want. Phone number, email, user id, cell phone handset id (IMEI), and so on - it's all the same. The restrictions against this are policy based, not technically based, and can change at any time.So the restrictions that keep the government from listening to your private communication are policy based rather than technically based - DUH. I'm sure there are lots of things the government could "technically" do - but they are prohibited by policy.
If you want to freak out about what the government MIGHT do if the policies changed, you can go join Snowden in the crazy corner. Otherwise, lets call in the fat lady to sing...this one is OVER by Snowden's own admission.