Legal Definitions - National Security Letter

A National Security Letter is a type of administrative demand issued by federal agencies, primarily the Federal Bureau of Investigation (FBI), to compel individuals or organizations to provide specific information relevant to national security investigations.

Unlike a traditional search warrant, a National Security Letter historically did not require prior approval from a judge. Instead, it was issued directly by the investigating agency. These letters often included a "gag order," which legally prohibited the recipient from disclosing that they had received the letter or complied with its demands. While designed to gather information quickly for critical national security matters, the lack of judicial oversight and the secrecy imposed by gag orders led to legal challenges. Courts have since ruled that these gag orders and the limited judicial review previously associated with National Security Letters violated First Amendment rights, leading to reforms in how they are used and reviewed.

• Example 1: Internet Service Provider (ISP)

  Imagine federal investigators are tracking a sophisticated cyber threat believed to originate from a foreign adversary. They suspect a particular online account is being used to coordinate these activities. Instead of seeking a warrant from a judge, the FBI might issue a National Security Letter to the internet service provider hosting that account. This letter would compel the ISP to provide non-content information, such as the subscriber's name, billing address, and connection logs (IP addresses used to access the account). Historically, the NSL would also have included a gag order preventing the ISP from informing the account holder or the public about the demand.

  This illustrates how an NSL allows a federal agency to quickly obtain specific subscriber and usage data from a private company for national security purposes, without initial judicial review, and historically with a strong secrecy requirement.

• Example 2: Financial Institution

  Consider a situation where the FBI is investigating potential financing for a terrorist organization. They identify a suspicious pattern of transactions involving a specific individual or entity. To gather more information, the FBI could issue a National Security Letter to a bank or other financial institution. This letter would demand records such as account holder details, transaction histories, and wire transfer information related to the suspected accounts. The bank would be legally obligated to comply, and in the past, would have been prohibited from disclosing the existence of the NSL to anyone, including the account holder, due to an accompanying gag order.

  This demonstrates the use of an NSL to compel financial institutions to provide sensitive customer data for national security investigations, highlighting its administrative nature and the historical secrecy surrounding its execution.