On a snowy afternoon in February 2004, an FBI agent came to Nick Merrill's door, bearing a letter that would change his life. At the time, Merrill was running a small internet service provider. The envelope that the agent carried contained what is known as a "national security letter", or NSL. It demanded details on one of his company's clients; including cellphone tower location data, email details and screen-names. It also imposed a non-disclosure agreement which was only lifted this week, when - after an 11-year legal battle by Merrill and the American Civil Liberties Union, he was finally allowed to reveal the contents of the letter to the world. The NSL which Merrill was given was a new use for what was a relatively old tool. The FBI had long - if sparingly - used them, [but] the Patriot Act vastly expanded the scope of what an NSL could be applied to. The FBI greatly increased the number issued; according to a 2007 inspector general's report, the NSL that Merrill was handed by the agent was one of nearly 57,000 issued that year. All of those thousands of NSLs were accompanied by a non-disclosure agreement, or "gag order" - which barred recipients were ever disclosing that they had received an NSL - even to the person whose records were being sought. With the ACLU, Merrill went to court to challenge the constitutionality of the letter, especially of the gag order. In 2014, Merrill sued again, helped by ... the Yale Law Clinic. Finally, [a] judge ... ruled that the gag order be completely lifted. It had taken Merrill almost 12 years.