For six years, Nicholas Merrill has lived in a surreal world of half-truths, where he could not tell even his fiancee, his closest friends or his mother that he is John Doe" -- the man who filed the first-ever court challenge to the FBI's ability to obtain personal data on Americans without judicial approval. No one knew he was the plaintiff challenging the FBI's authority to issue "national security letters," as they are known, and its ability to impose a gag on the recipient. Now, following the partial lifting of his gag order 11 days ago as a result of an FBI settlement, Merrill can speak openly for the first time about the experience, although he cannot disclose the full scope of the data demanded. "One of the most dangerous and troubling things about the FBI's national security letter powers is how much it has been shrouded in secrecy," said Melissa Goodman, a lawyer with the American Civil Liberties Union who helped Merrill sue the government in April 2004 and was one of only a handful of people outside the FBI -- all lawyers -- who knew Merrill had received a letter. The FBI between 2003 and 2006 issued more than 192,500 letters -- an average of almost 50,000 a year. The Justice Department inspector general in 2007 faulted the bureau for failing to adequately justify the issuance of such letters.