A FOIA request and a subsequent lawsuit by the American Civil Liberties Union and the New York Civil Liberties Union resulted in the release of these Department of Defense documents related to the use of National Security Letter powers. The ACLU stated, "New documents uncovered...reveal that the Department of Defense secretly issued hundreds of national security letters (NSLs) to obtain private and sensitive records of people within the United States without court approval. A comprehensive analysis of 455 NSLs issued after 9/11 shows that the Defense Department seems to have collaborated with the FBI to circumvent the law, may have overstepped its legal authority to obtain financial and credit records, provided misleading information to Congress, and silenced NSL recipients from speaking out about the records requests, according to the ACLU.
NSLs are secretly issued by the government to obtain access to personal customer records from Internet service providers, financial institutions, and credit reporting agencies. In almost all cases, recipients of the NSLs are forbidden, or "gagged," from disclosing that they have received the letters. While the FBI has broad NSL powers and compliance with FBI-issued NSLs is mandatory, the Defense Department's NSL power is more limited in scope, and, in most cases, compliance with Defense Department demands is not mandatory."