Civil libertarians are elated in the wake of a federal court ruling declaring it unconstitutional for the government to issue so-called national security letters (NSLs), demands for internal information that prohibit companies or other organizations that receive them from disclosing that the letters have been sent to them.

A national security letter is somewhat like a subpoena in that it demands information such as the e-mail addresses and telephone numbers of a firm’s customers (not the content of the e-mails or calls). But unlike a subpoena or warrant, it can be issued without court approval. Typically the letters are sent by the FBI, but they have also been issued by other agencies, such as the CIA and the Pentagon.

One of the most publicized uses of NSLs has involved FBI demands for information from libraries about which patrons were checking out certain books; such a demand on a consortium of libraries in Windsor, Conn. in 2005 Vermont Senator Patrick Leahy, chairman of the Senate Judiciary Committee, called “Kafka at the extreme.”

The most controversial feature of the letters from the standpoint of civil liberties has been the fact that their receipt had to be kept secret, a feature seen as a violation of the First Amendment guarantee of freedom of speech. Customers could not be notified that their information had been handed over to a government agency; the receipt of the letter could not be disclosed to the press.

In U.S. District Court in San Francisco on March 14, Judge Susan Illston agreed that that built-in gag order violated the First Amendment and has ordered government agencies to stop sending the letters, though she has also put a 90-day hold on her ruling to give the government time to offer arguments against it.

Illston’s judgment came as a result of a suit filed by the Electronic Frontier Foundation on behalf of a client that at press time had not been named publicly, but that was believed to be Credo, a telecommunications firm in San Francisco. Credo is a property of Working Assets, a telephone and credit card company that applies a portion of the fees it collects to support social and political action (“Recently our members helped expand health coverage to millions of low-income kids, pressed for new rules to curb global warming emissions and added momentum to the marriage equality movement,” says the Working Assets website).

NSLs came into existence in 1978, but were only used when the targeted information concerned a foreign country, or an entity the government believed was an operative for a foreign country. In 1993 the law changed to allow their use when no connection with foreign powers was suspected. But it was after the attacks on Sept. 11, 2001 and the passage of the Patriot Act that their use expanded and agencies other than the FBI were allowed to use them. Last year, more than 16,000 NSLs were issued.•