Government snooping - what's legal?

Citing a May 11 USA Today article reporting that the National Security Agency (NSA) "has been secretly collecting the phone call records of tens of millions of Americans, using data provided by AT&T, Verizon and BellSouth," the Congressional Research Service (CRS) issued a paper May 17 summarizing legal authorities for the Government to access telephone calling information "for either foreign intelligence or law enforcement purposes."

In a U.S. Supreme Court case, Smith v. Maryland, and in the U.S. Code, in the Foreign Intelligence Surveillance Act (FISA), 50 U.S.C. §1841 et seq., and for law enforcement purposes in 18 U.S.C. §3121 et seq., CRS discusses the use of pen registers and trap and trace devices. "Pen register" and "trap and trace device" are defined in 18 U.S.C. §3127 (3) and (4) as, basically, devices which record information to identify the source of a wire or electronic communication. The report also covers other Code sections relating to criminal investigations, business records, stored electronic communications, and the Communications Act of 1934 (pdf), as amended, specifically 47 U.S.C. §222 , and §§501-503.

Government Access to Phone Calling Activity and Related Records: Legal Authorities, CRS Report RL33424, May 17, 2006
(pdf, 88KB, 19p., from Open CRS)