Documents unsealed Thursday by a federal court in Seattle reveal that late last year, Microsoft successfully challenged an FBI National Security Letter.
NSLs allow FBI officials to send requests to Web and telecommunications companies requesting account information, with the assumption that the information is relevant to a national security investigation.
The NSL Microsoft received was in regard to one of its enterprise customers and it sought basic subscriber information, Microsoft's general counsel Brad Smith said in a blog post.
Like all NSLs, the one Microsoft received contained a gag order that prevented it from notifying its customer about the request, which spurred Microsoft to take legal action.
Smith noted a previous blog post from December where he had pledged that Microsoft would notify its customers if any legal orders were received relating to their data.
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.
Smith said government requests for enterprise customer data are rare, but that the win was reassuring for its approach to securing customer data. Still, the bigger war for disclosure is far from over.