Tim Lee runs down some little-known facts about the original growth of the secret, illegal surveillance state as the FBI, with administration approval, decided to ignore a series of court rulings in the 1930s, 40s, and 50s that attempted to restrain its ability to wiretap in a variety of ways. These practices, of course, were per se abusive in many ways, and led to further abuses, and then under Richard Nixon led to the revelation of massive abuses and the creations of the safeguards we're now busy unwinding.
I suppose at this point I've become fatalistic about FISA and am mostly just waiting for this whole cycle to repeat itself.
UPDATE: See also this important followup about crass politicization of surveillance and this crucial point: "Now, I have no evidence that today’s NSA or FBI is doing anything like this. But of course, someone in the 1960s wouldn’t have realized what the FBI was doing then, either."