Yesterday morning, Microsoft released, along with its most recent biannual transparency reports, a 2014 National Security Letter (NSL) from the FBI which sought “data belonging to belonging to a customer of our consumer services,” according to the company’s press release on the matter.
National Security Letters
Under U.S. law, the FBI may issue a National Security Letter (NSL) to a third-party record holder as part of an authorized national security investigation. NSLs may be issued without a warrant or other judicial involvement, but can be used only to acquire information that is not content---for example, transactional records or subscriber information. After 9/11, the PATRIOT Act expanded the permissible uses of NSLs beyond just of foreign powers and their agents to investigations of terrorism. The FBI’s revitalized use of NSLs in post-9/11 counterterrorism soon came under scrutiny over lack of transparency and absence of judicial involvement.