The FBI can compel businesses, banks and other entities to surrender all sorts of sensitive customer records with a National Security Letter, or NSL, without seeking or obtaining judicial approval. The requests are typically accompanied by gag orders that prevent recipients from acknowledging their existence as well, but passage of the USA Freedom Act in 2015 allows those orders to be eventually lifted after the fact if the FBI agrees.

In its latest biannual transparency report published Thursday, Microsoft said for the first time ever that an NSL issued by the government in January 2014 "sought data belonging to a customer of our consumer services."

"Microsoft is the latest in a series of companies able to disclose an NSL due to provisions in the USA Freedom Act requiring the FBI to review previously issued non-disclosure orders," Microsoft's director of corporate responsibility, Steve Lippman, said in a blog post. "The reforms in the USA Freedom Act were a positive step forward and we believe reasonable limits on the routine use of government secrecy should be adopted more broadly."