During 2012, Google says they received “national security letter” requests for up to 2,000 accounts from the Federal Bureau of Investigation. National security letters are a tool used by the FBI and other government agencies to gather financial, phone and Internet data without a warrant. National security letters are normally subject to gag orders and even acknowledging their existence can land the recipient in hot water. Nevertheless, Google provides period reports concerning the number of inquiries it receives pursuant to the letters.
Google has provided these numbers in the past. In 2009 they received up to 1,000 letters and in 2010 the range was between 2,000 and 3,000 users. Google only releases a range for the number of letters of received due to concerns expressed by the FBI and other agencies about the impact on active investigations if exact numbers were released.
In their most recent release, Google also provided some information regarding their policy for responding to the letters. They indicate that they do not believe the government can obtain Gmail content, search query information, videos, or even user IP addresses. Most companies will not provide any information about the letters received or they will indicate in a very generic fashion that they comply with all legal requests for information. The FBI has provided template information regarding the letters which companies may respond to with up to thirteen different data points. However, only two points are known – “transaction/activity logs” and “header information” from emails.
source: The Wall Street Journal