	Introduction

Five statutory provisions vest government agencies responsible for certain foreign intelligence investigations (principally the Federal Bureau of Investigation (FBI)) with authority to issue written commands comparable to administrative subpoenas. USA PATRIOT Act

The USA PATRIOT Act amended three of the four existing NSL statutes and added a fifth. Their amendments: 
created a judicial enforcement mechanism and a judicial review procedure for both the requests and accompanying nondisclosure requirements; established specific penalties for failure to comply or to observe the nondisclosure requirements; made it clear that the nondisclosure requirements did not preclude a recipient from consulting an attorney; provided a process to ease the nondisclosure requirement; expanded congressional oversight; called for an Inspector General's audit of use of the authority. More specifically, the report found that
a "significant number of NSL-related possible violations were not being identified or reported" as required; the only FBI data collection system produced "inaccurate" results; the FBI issued over 700 exigent letters acquiring information in a manner that "circumvented the ECPA NSL statute and violated the Attorney General's Guidelines ... and internal FBI policy;" the FBI's Counterterrorism Division initiated over 300 NSLs in a manner that precluded effective review prior to approval; 60% of the individual files examined showed violations of FBI internal control policies; the FBI did not retain signed copies of the NSLs it issued; the FBI had not provided clear guidance on the application of the Attorney General's least-intrusive-feasible-investigative-technique standard in the case of NSLs; the precise interpretation of toll billing information as it appears in the ECPA NSL statute is unclear; SAC supervision of the attorneys responsible for review of the legal adequacy of proposed NSLs made some of the attorneys reluctant to question the adequacy of the underlying investigation previously approved by the SAC; there was no indication that the FBI's misuse of NSL authority constituted criminal conduct; personnel both at FBI headquarters and in the field considered NSL use indispensable; and information generated by NSLs was fed into a number of FBI systems. The Second IG Report

The second IG Report reviewed the FBI's use of national security letter authority during calendar year 2006 and the corrective measures taken following the issuance of the IG's first report. A federal district court there agreed with the Second Circuit that the NSL confidentiality and judicial review provisions were constitutionally suspect. Recommendations of the President's Review Group

In the wake of leaks relating to the National Security Agency's (NSA's) purported bulk meta-data collection program under the Foreign Intelligence Surveillance Act (FISA), the President established a Review Group on Intelligence and Communications Technology (Group). Several of its recommendations addressed NSLs. NSL procedures, it said, should more closely resemble those of FISA "business record" court orders ("§215 orders"). Finally, it augments existing reporting requirements for greater transparency. The USA FREEDOM Act handles the judicial review of nondisclosure orders with complementary amendments to the NSL statutes and to Section 3511. The National Security Act NSL authority is available to conduct law enforcement investigations, counterintelligence inquiries, and security determinations. Moreover, Section 119 of the USA PATRIOT Improvement and Reauthorization Act instructs the Inspector General of the Department of Justice to audit and to report to the judiciary and intelligence committees as to the Department's use of the authority in the years following expansion of the authority in the USA PATRIOT Act. It authorizes recipients to periodically disclose publicly the number of NSLs and requests they have received as well.
Five federal statutes authorize intelligence officials to request certain business record information in connection with national security investigations. The authority to issue these national security letters (NSL) is comparable to the authority to issue administrative subpoenas. The USA PATRIOT Act (P.L. 107-56) expanded the authority under the original four NSL statutes and created a fifth. Thereafter, the authority was reported to have been widely used. Then, a report by the Department of Justice's Inspector General (IG) found that in its use of expanded USA PATRIOT Act authority the FBI had "used NSLs in violation of applicable NSL statutes, Attorney General Guidelines, and internal FBI policies," although it concluded that no criminal laws had been broken. A year later, a second IG report confirmed the findings of the first, and noted the corrective measures taken in response. A third IG report, critical of the FBI's use of exigent letters and informal NSL alternatives, noted that the practice had been stopped and related problems addressed.
The USA PATRIOT Improvement and Reauthorization Act (P.L. 109-177, and its companion, P.L. 109-178) amended the five NSL statutes to expressly provide for judicial review of both the NSLs and the confidentiality requirements that attend them. The sections were made explicitly subject to judicial enforcement and to sanctions for failure to comply with an NSL request or to breach NSL confidentiality requirements. Prospects of its continued use dimmed, however, after two lower federal courts held that the absolute confidentiality requirements and the limitations on judicial review rendered one of the NSL statutes constitutionally suspect.
The President's Review Group on Intelligence and Communications Technologies recommended several NSL statutory adjustments designed to eliminate differences between NSLs and court orders under the Foreign Intelligence Surveillance Act ("§215 orders"), including requiring pre-issuance judicial approval of NSLs. Instead in the USA FREEDOM Act, P.L. 114-23 (H.R. 2048), Congress opted to adjust the NSL judicial review provisions governing the nondisclosure requirements which may accompany NSLs. It also precludes the use of NSL authority for bulk collection of communications or financial records. Finally, it adjusts existing reporting requirements to permit recipients to publicly disclose the extent to which they have been compelled to comply with NSLs.
The text of the five NSL statutory provisions has been appended. This report is available abridged—without footnotes, appendices, and most of the citations to authority—as CRS Report RS22406, National Security Letters in Foreign Intelligence Investigations: A Glimpse at the Legal Background, by [author name scrubbed].