Much of the concern about the letters has focused on the gag orders, which accompany nearly every request and prevent the recipient — typically indefinitely — from disclosing even the existence of the letter. The federal government has argued that the secrecy is necessary to avoid alerting targets, giving would-be terrorists clues about how the government conducts its surveillance or hurting diplomatic relations.
After a series of court rulings found that the gag orders violated First Amendment protections, Congress enacted the review requirements.
The documents obtained through the lawsuit include the number of orders reviewed, as well as redacted copies of 751 letters from the F.B.I. informing companies and organizations their gag orders had been lifted. These so-called termination letters do not reveal the contents of the original national security letters, but indicate which entities received them.
Because so few gag orders have been reviewed and rescinded, it isn’t possible to say whether the companies that received the most termination letters also received the most national security letters. But given the overall secrecy around the program, the termination letters offer a rare glimpse into these subpoenas.
Equifax, Experian and AT&T received the most termination letters: more than 50 each. TransUnion, T-Mobile and Verizon each received more than 40. Yahoo, Google and Microsoft got more than 20 apiece. Over 60 companies received just one.
The underlying national security letters were not included in the documents, and it is unclear when most of them were issued and who the individual targets were.