It is never read by humans though unless flagged.
And hopefully there are checks-and-balances in place to alert others if a government employee is accessing data about someone that he personally knows.
It's not as easy as "only save texts with the words bomb and weed in them". It's all saved, then analyzed, then retained a few years, then eventually deleted. Is that acceptable for the US government to do?
It's also amusing how sure you seem about some things, while also adding in a few "hopefully"-s here and there. The truth is, you don't have any idea what they're doing because they don't tell anybody.
Well, the US government did grant immunity to the big TelComs for their participation in the "Domestic" surveillance program a few years ago...
That tells me all I need to know.
RedPhone anyone? http://www.whispersystems.org/
With the criteria for being "flagged" remaining secret. Are you a dissident? Now the government can make your life difficult by leaking information about your brief extramarital affair. Maybe the government will concoct a sexual assault case against you to shut you up.