Google has posted a “Transparency Report” that provides a range of how many National Security Letters (NSLs) it has received and a range of how many users/accounts were specified in these NSLs each year since 2009. Of course, your first question may be: What is an NSL?
An NSL is a special search vehicle by which the FBI has the authority to demand the disclosure of customer records maintained by banks, Internet Service Providers, telephone companies and other entities. When this happens, these entities are prohibited from revealing to others their receipt of an NSL. There have been reports that the issuance of NSLs has expanded significantly since the Patriot Act increased the FBI’s power to issue them.