A National Security Letter (NSL), a tool of the USA Patriot Act, is a demand from an intelligence agency (FBI, CIA, DoD,etc.) for information. It requires no judicial oversight and routinely comes with a gag order. The recipient may not reveal even the existence of the letter. Among other uses, it has reportedly been sent to most Internet Service Providers to obtain information about all of their customers. Between 2003 and 2006 nearly 200,000 national security letters were sent out. A federal judge has ruled that the gag order is a violation of the First Amendment. The case is now before a 3 judge panel of the US Second Circuit Court of Appeals. -- Reuters reports.

In the meantime, you, your business, and your personal affairs are no longer afforded much privacy.