An email encryption service in Texas recently announced that it is shutting down, but they can't explain why. However, internet security sleuths have pretty well figured out their dilemma. It appears that they might go to jail if they explained why. All the circumstances clearly suggest that they received a letter, a very nasty letter from the ruling class's government. See if you agree.
...if you get one, you can't tell anyone about it. Nobody, not even family or friends let alone the people you work with (even if they are affected by the letter's demands) can ever be told you received a National Security Letter. If you do tell anyone, you go to jail. That prohibition--an astonishing violation of your First Amendment right of free speech, particularly considering that the letter is from a law enforcement agency, not a court--lasts forever unless you go to court and manage to get it lifted--something which rarely happens. But these letters are hardly rare. From 2003 to 2006 alone the Federal Bureau of Investigation issued 192,499 national security letter requests (and the frequency of their use has almost certainly increased since then.)