How is it legal for the National Security Agency to gather data on the phone records of millions of Americans? It turns out the Foreign Intelligence Surveillance Court has been expanding the definition of the word “relevant” as it applies to information used to fight terrorism. A series of classified orders from the FISC show that in the mid-2000s the court began accepting the rationale that relevant materials could mean an entire database of records. The Patriot Act allows federal authorities to force businesses to furnish records as long as the bureau proves the information is "relevant to an authorized investigation" of terrorism. And, it's up to the judges to define what's "relevant."