From Google’s blog today:
.. When conducting national security investigations, the U.S. Federal Bureau of Investigation can issue a National Security Letter (NSL) to obtain identifying information about a subscriber from telephone and Internet companies. The FBI has the authority to prohibit companies from talking about these requests. But we’ve been trying to find a way to provide more information about the NSLs we get—particularly as people have voiced concerns about the increase in their use since 9/11.
Starting today, we’re now including data about NSLs in our Transparency Report. We’re thankful to U.S. government officials for working with us to provide greater insight into the use of NSLs. Visit our page onuser data requests in the U.S. and you’ll see, in broad strokes, how many NSLs for user data Google receives, as well as the number of accounts in question. In addition, you can now find answers to some common questions we get asked about NSLs on our Transparency Report FAQ.