The Foreign Intelligence Surveillance Court on Tuesday offered its most extensive public explanation for why it has allowed the government to keep records of all Americans’ phone calls, releasing a previously classified opinion in which it said the program was constitutional and did not violate Americans’ privacy rights.While the once-secret call log program has been periodically reapproved by the court since 2006, it has come under criticism from members of Congress of both parties and civil libertarians since its existence came to public light in June after leaks by the former National Security Agency contractor Edward J. Snowden.
http://www.nytimes.com/2013/09/18/us/opinion-by-secret-court-calls-collection-of-phone-data-legal.html