Even without CALEA, if I'm reading the press coverage right, the FISA orders to which Google comply once they check that they were issued by FISC can be very broad, including "give me ALL the metadata you have" in a single order. Because "taking all metadata an storing it indefinitely is nothing to be worried about" in NSA interpretations.
Well all metadata wouldn't work as that could be used to intercept U.S. persons' data. The warrant/NSL would have to list by name/UID at the very least, but once it's established that the UID in question is foreign and a part of an investigation then you are right that the warrant/NSL can be very broad.
How can you say "all metadata wouldn't work"? Thanks to Snowden, here's the full single FISC order which says "give the all metadata you have":
http://www.guardian.co.uk/world/interactive/2013/jun/06/veri...
Moreover the language it was written implies that the same order was made to the other providers, changing just the recipient.
(If you are on the network which blocks access to Guardian, http://www.guardian.co.uk/world/2013/jun/28/us-army-blocks-g... you're missing a lot! Visit some friends, surf from their computer.)
Actually, yes, the feds are using Section 215 of the Patriot Act to get FISC orders on all metadata of Americans' domestic phone and internet communications from ISPs and phone companies. The feds are leveraging a theory that you have no privacy interest in your metadata, thus no 4th Amendment violation.
It's not clear at all that this is legal, especially given the Supreme Court's recent ruling in Jones, requiring warrants for GPS tracking of automobiles.
CALEA does not apply to Google (except Google fiber and perhaps Google Voice). Google does have to comply with FBI requests for emails and stored data, but they do not have to comply with CALEA (which mandates technical standards for the wiretapping of the phone network and most internet networks). Google does NOT have to build real-time domestic spying tools for the government, though it is arguable whether the 702 program (which PRISM is part of) does.
The FBI would LOVE to extend CALEA to Facebook and Google, etc, but this has not happened yet.
That said, it is likely that the FBI's backbone spying network (DCSNET), which was built for CALEA, is being used for PRISM.