I suggest you read the article I linked above, which is filled with additional links that go beyond plausibility and point to straight up reality. It's some of the most eye opening information I have read in decades.
NSA overreach and parallel construction are topics so widely acknowledged as real, that they have appeared as plot lines in legal themed shows on mainstream television shows like Good Wife (which is an excellent show, btw).
You need to read up on Bill Binney's story. He was the NSA's principal architect of the original versions of the pre-9/11 data mining software. There were two versions being considered. The one he endorsed was a targeted approach to eavesdropping on communications that involved key words and phrases specific to terrorism threats. The other version simply swept up EVERYTHING, and was cripplingly expensive, and too comprehensive to be of any reasonable use for snooping out terrorism threats - and most importantly, was highly problematic in Binney's opinion relative to being unconstitutional.
After 9/11, he was furious about the NSA's decision to focus on the second version, and claimed that decision was responsible for the failure to detect the hijacking operations that likely would have been detected with the first version. He blew the whistle, using the government approved whistleblowing protocol, and subsequently had his career and his reputation destroyed because of it - big surprise!
Now we have evidence of how obscenely large the PRISM system is, making it clear that it is of no value for real time detection of threats. It is nothing but a mega ocean of stored private communications, useful only for trudging through for any number of nefarious reasons. There are literally millions of people in this country who hold a security clearance. There is also clear evidence of these people using this system to eavesdrop on acquaintances for personal reasons, and evidence that the vast majority of emails and text messages being read through involve drama and sexual matter having nothing to do with terrorism threats. Russia even warned us specifically of two radicals in a known location in the US who are suspected extremists, yet they easily succeeded in pulling off the Boston Marathon bombings regardless. Why? Because the surveillance system we have in place isn't even concerned with stopping terrorism. It has been of zero value in that respect, despite the crippling expense its actual targets have shouldered to build it. Americans, like Angela Merkel and the rest of the international community, should be absolutely outraged over this. The government knows this, and would be insanely stupid to not be actively trying to downplay this disgraceful situation. Enter the villain/hero Edward Snowden, safely tucked away where he is untouchable. It's all too convenient.
The US imprisons more of its citizens than some of the worst dictatorships that exist throughout the world. How do so many people get caught for imprisonable offenses? Parallel construction. Illegal, warrantless wiretaps are used to mine information. That information can't be used in court, and is instead used to set up a victim. When you read a news story about how a car was randomly pulled over for something benign like a marked lane violation, and they decided to search the car and found a pile of drugs - that was no random occurrence. The officers knew where to be and at what time to be there. Law enforcement has already admitted that this is a flagrantly used technique. It's all part of the same abusive scam. The system is overtly unconstitutional, and there are too many operators that benefit from abusing it to think that it's ever going to be corrected.