The FBI served Google with a “national security letter” in early 2015, the company has revealed in this week’s transparency report, and obliged the company to keep the matter secret under a gag order until now. National security letters allow the FBI to covertly subpoena data from companies without having to get a court order, so long as
Google Reveals Secret FBI Subpoena, Reports Increase In FISA Requests
The government severely limits the ability of companies to make the exact details of their surveillance public, with gag orders keeping some actions secret outright.