The Wayback Machine - https://web.archive.org/web/20170103043118/https://www.theguardian.com/world/interactive/2013/jun/20/exhibit-a-procedures-nsa-document

Procedures used by NSA to target non-US persons: Exhibit A – full document

Top-secret documents show Fisa judges have signed off on broad orders allowing the NSA to make use of information 'inadvertently' collected from domestic US communications without a warrant

Revealed: the secret rules that allow NSA to use US data without a warrant