From the Washington Post article that broke the PRISM story, the program through which the NSA and the FBI extract audio and video chats, photographs, e-mails, documents, and connection logs directly from nine major US internet companies (but not Twitter):
Wyden repeatedly asked the NSA to estimate the number of Americans whose communications had been incidentally collected, and the agency’s director, Lt. Gen. Keith B. Alexander, insisted there was no way to find out. Eventually Inspector General I. Charles McCullough III wrote Wyden a letter stating that it would violate the privacy of Americans in NSA data banks to try to estimate their number.
How do you follow
that?