anyone who believes the FBI and a host of other U.S. agencies even less scrupulous does not wiretap without permits, has been standing behind the door. generally, it does not matter if the information learned is admissable in court --they never admit wiretapping in the first place as the agency themselves, in many cases, *did*not*wiretap* --but the agency does buy info from usually unsavory "contractors" who do wiretap.
Here is where I'm totally amazed (aghast ... maybe I'm just too naive): (And, yes, I have asked this question, in different words, to a lawyer crowd.) It is clear that if the FBI/CIA/NSA/ATF/DoS intercepts a message with some very important content, like, say, I (Ernest Hua) was plotting to kill Hillary, then they can use that information to start investigating my activities, even if the intercept turned out to be illegal. Those who saw the content of this intercept is not required by law to "forget" that they ever saw it. In this day and age, having discretionary access to information is a lot of power which the average citizen does not have. Even just the ability for an entity to see information which it legally may not intercept gives that entity a lot more power than I would ever want to grant them. I am sure a networked video camera in every room, street corner, and passenger car is one of the FBI's wet dreams. No thanks. Human beings are human beings, and we all have flaws. That is why there are companies in Britain selling videos of people caught in the act of doing something private in a public place. (Of course, if I were Hillary in this scenario, then I would wish that the FBI/et al has god-like powers to do anything to stop me, but that would be an emotionally charged argument and not a rational one.) Ern