For three years, the Bush administration has drawn fire from civil liberties groups over its use of national security letters, a kind of administrative subpoena that compels private businesses such as telecommunications companies to turn over information to the government. After the 2001 USA Patriot Act loosened the guidelines, the FBI issued tens of thousands of such requests, something critics say amounts to warrantless spying on Americans who have not been charged with crimes. Now, newly released documents shed light on the use of the letters by the CIA. The spy agency has employed them to obtain financial information about U.S. residents and does so under extraordinary secrecy, according to the American Civil Liberties Union, which obtained copies of CIA letters under the Freedom of Information Act. The CIA's requests for financial records come with gag orders" on the recipients, said ACLU lawyer Melissa Goodman. In many cases, she said, the recipient is not allowed to keep a copy of the letter or even take notes about the information turned over to the CIA. The ACLU posted copies of some of the letters on its Web site. In most cases, nearly all the text had been redacted by CIA censors.