Microsoft has disclosed that it received a secret subpoena from the FBI, which demanded the company turn over personal information on a customer.
The company confirmed in a Thursday blog post that it received the subpoena, a so-called "national security letter" filed in 2014, but came with a gag order preventing the company or anyone else from disclosing the contents -- even to the customer in question.
The subpoena doesn't require a judge or a court to approve the turning over of the customer's data.
It's not known exactly what the FBI wanted from this customer's accounts. Under existing law, national security letters can get access to all kinds of metadata -- but not contents of calls, emails, and other messages, which do require a court order.
Microsoft said that the national security letter was included in the aggregate data of an earlier transparency report.
Provisions in the Freedom Act, passed in 2015 as an intelligence community reform effort after the Snowden revelations, compel the FBI to periodically review the gag orders that are attached to national security letters. That in part resulted in details of the letters becoming public for the first time, including challenges from Facebook, Yahoo, and Cloudflare.
"There are times when secrecy is vital to an investigation, but too often secrecy orders are unnecessarily used, or are needlessly indefinite and prevent us from telling customers of intrusions even after investigations are long over," said Steve Lippman, Microsoft's director of corporate responsibility.
The company also disclosed during the first half of 2016 that it received between zero and 499 secret FISA orders -- the same as the previous six months -- but with significantly fewer accounts affected.
On April 26, the company corrected the number of FISA orders it received, after initially saying it received between 1,000 and 1,499 orders.