Yes but it relies on an informed electorate holding mostly honest elected officials to account while said officials hold the tools of state to account.
In other words no.
In other words no.
Seems to me that the judicial system needs to get more involved in this. Congressional oversight of NSA, TSA, DOD, etc has not really worked.
There is also a role for technology to play. Out of millions of calls, billions of emails, how do you flag that one bad guy? The implicit assumption in such a problem is that you collect the data on everyone so that you can look for patterns of bad guy behavior. But is there another way?