The NSA's contractors are sucking up everything digital, way more than the obvious stuff, and storing it. They don't look at it, so that by the broadest (both eyes shut and sphincter clenched) interpretation of the 4th amendment that's not a 'search'.
The thing is, it's all 'indexed' by digital identifiers. That means once they get a secret warrant, or maybe just a 'National Security Letter' which isn't even reviewed by a rubber stamp judge, they can look at anything linked to the original subject. This could, according to the 'Kevin Bacon theorem' of higher probability mathematics, [okay that is some what an exaggeration] you could look at all material they've stored on everybody based on one order. So really, they don't need very many court orders.