Microsoft successfully challenged the FBI on a user information request issued in 2013, the win was detailed in recently unsealed documents pertaining to the request for "basic subscriber information" on a Enterprise customer .

Microsoft argued that providing the information requested in the order to the government would violate the First Amendment.

Microsoft General Counsel & Executive Vice President, Brad Smith goes on to explain the case in detail on the company's TechNet blog; On Thursday, a federal court in Seattle unsealed documents related to an FBI National Security Letter that Microsoft successfully challenged in court late last year. This marks an important and successful step to protect Microsoft's enterprise customers regarding government surveillance.

Because information about the case wasn’t public until today, this is our first opportunity to discuss it in detail. Given the strong ongoing worldwide interest in these issues, we wanted to provide some additional context on the matter.

The FBI’s letter in this case sought information about an account belonging to one of our enterprise customers. Enterprise customers at Microsoft include legitimate businesses, governments, and non-governmental organizations. Like all National Security Letters, this one sought only basic subscriber information.

In this case, the Letter included a nondisclosure provision and we moved forward to challenge it in court. We concluded that the nondisclosure provision was unlawful and violated our Constitutional right to free expression. It did so by hindering our practice of notifying enterprise customers when we receive legal orders related to their data.

After we filed this challenge in Federal Court in Seattle, the FBI withdrew its Letter.

For over two centuries individuals in the United States have turned to the courts to protect our most fundamental freedoms. This case demonstrates the vital role our courts continue to play and the cause for confidence they provide.