"Recent attention concerning National Security Agency (NSA) surveillance pertains to unauthorized disclosures of two different intelligence collection programs. Since these programs were publicly disclosed over the course of two days in June, there has been confusion about what information is being collected and under which authorities the NSA is acting. This report clarifies the differences between the two programs and identifies potential issues that may help Members of Congress assess legislative proposals pertaining to NSA surveillance authorities. The first program collects in bulk the phone records--including the number that was dialed from, the number that was dialed to, and the date and duration of the call--of customers of Verizon and possibly other U.S. telephone service providers. It does not collect the content of the calls or the identity of callers. The data are collected pursuant to Section 215 of the USA PATRIOT ACT, which amended the Foreign Intelligence Surveillance Act (FISA) of 1978. Section 215 allows the FBI, in this case on behalf of the NSA, to apply to the Foreign Intelligence Surveillance Court (FISC) for an order compelling a person to produce 'any tangible thing,' such as records held by a telecommunications provider, if the tangible things sought are 'relevant to an authorized investigation.' Some commentators have expressed skepticism regarding how such a broad amount of data could be said to be 'relevant to an authorized investigation,' as required by the statute."
CRS Report for Congress, R43134