The companies can withhold consent simply by not consenting. Both NSA and the company then have to appear before a federal court and argue the case; a court then orders one side or the other (obviously: virtually always the company) to back down.
It bothers people that the USG virtually always wins these cases. But I think it shouldn't bother people as much as it does, for a couple of reasons:
* It's also the case that state governments win most attempts to get Title III wiretaps; in those cases, it's because getting a Title III wiretap is an expensive process that involves a shitload of paperwork, and prosecutors don't waste the time going for them unless they're sure they're going to win. It appears easier to get a FISA directive upheld, but it's not free.
* It's what you'd expect to see happen if the USG was only using FISA to conduct foreign surveillance, which, while I wouldn't take NSA's word for it, is not at all hard to believe; what is the motivation for them to set up a paper trail with the FISC of doing something else?
It bothers people that the USG virtually always wins these cases. But I think it shouldn't bother people as much as it does, for a couple of reasons:
* It's also the case that state governments win most attempts to get Title III wiretaps; in those cases, it's because getting a Title III wiretap is an expensive process that involves a shitload of paperwork, and prosecutors don't waste the time going for them unless they're sure they're going to win. It appears easier to get a FISA directive upheld, but it's not free.
* It's what you'd expect to see happen if the USG was only using FISA to conduct foreign surveillance, which, while I wouldn't take NSA's word for it, is not at all hard to believe; what is the motivation for them to set up a paper trail with the FISC of doing something else?