Google has published some of the National Security Letters [pcworld.com] (NSLs) it has received from the FBI:
Google is providing for the first time a look into the world of national security letters -- demands from the Federal Bureau of Investigation to hand over details about account holders and keep quiet about it.
The letters are a part of business for Google and other major internet companies, but traditionally they have been barred from acknowledging the letters' existence. That changed in 2013 when, in light of revelations about Internet surveillance by U.S. intelligence agencies, Google and others started fighting to disclose more about the demands.
That led to the creation of Google's "transparency report, [google.com]" which revealed the company receives thousands of requests for user data each month from law enforcement agencies around the globe. The national security letters remained secret, but on Tuesday, Google published a handful that are no longer covered by nondisclosure rules.
Google has redacted the email addresses of the users targeted as well as the names of the FBI employees who made the requests [blog.google], so don't expect anything exciting in the letters.