Secret letters from the FBI to ISPs have been published without redactions for the first time ever. What they revealed is a dangerous practice that circumvents many legal proceedings while compromising personal privacy.

Law enforcement would use secretive but official letters demanding compliance from ISPs to government requests. These National Security Letters compel companies to give out private user data without any need for warrants, The Next Web reported.

Nicholas Merril, founder of Calyx Internet Access, decided to take the matter to court. He received an NSL in 2004 demanding subscriber personal data which included complete Web browsing history, IP addresses of all individuals they contacted, and all records of online purchases. See PDF here.

The NSL was made into law in 2001 as part of the US Patriot Act, a result of the 9/11 attacks. The only thing required is a signature from an FBI agent and the NSL would also have a gag order with it. This means recipients would not be able to disclose any and all contents of the FBI's demands.

In The Verge report, Merril explained why the NSL's, of which hundreds of thousands were sent out, are a serious threat to privacy:

"The FBI has interpreted its NSL authority to encompass the websites we read, the web searches we conduct, the people we contact, and the places we go. This kind of data reveals the most intimate details of our lives, including our political activities, religious affiliations, private relationships, and even our private thoughts and beliefs."

NSLs have been sent out to banks, car dealers, insurance companies, doctors, and anyone the government deems a target. The presence of non-disclosure agreements did not stop some information from leaking out.

In 2007, the Office of the Inspector General revealed that approximately 40,000 to 60,000 NSLs would be sent out per year. In 2013, President Obama's Intelligence Review Group reported that government agencies sent out nearly 60 NSLs per day.