A report in Wired has exposed the shady way in which the FBI is using National Security Letters (NSL) and 2001's Patriot Act to spy on American citizens, potentially breaching their constitutional rights to privacy in the process. An unnamed communications provider is currently fighting an NSL demanding information on one of its users, who the FBI claims represents a threat to national security. The letter, which has been published with sensitive information redacted, instructs the company to tell nobody — especially not the target of the investigation — of its existence.

NSLs are not a new concept, having first been introduced in the 1980s. The introduction of the Patriot Act allowed them to be used far more aggressively, though, with the US Department of Justice recording a peak of 49,425 uses of the letters in 2006. By means of an NSL, the FBI is able to demand information on a user without a warrant, and place a gagging order on the company that prevents it discussing the case. Judges have previously expressed concern that the gag orders could also limit judicial review of the system, and force the courts to assume that the NSLs are necessary.

The American Civil Liberties Union has long expressed concern over the use of NSLs, frequently filing freedom of information requests in order to uncover more details over their use. With the question marks over their constitutional legality never settled, the gagging orders are occasionally beaten in court — famously in the case of Nicholas Merrill, a former owner of a small ISP who successfully quashed the order after a six-year-long fight.