Top secret documents submitted to the court that oversees surveillance by US intelligence agencies show the judges have signed off on broad orders which allow the NSA to make use of information "inadvertently" collected from domestic US communications without a warrant.
The Guardian is publishing in full two documents submitted to the secret Foreign Intelligence Surveillance Court (known as the Fisa court), signed by Attorney General Eric Holder and stamped 29 July 2009. They detail the procedures the NSA is required to follow to target "non-US persons" under its foreign intelligence powers and what the agency does to minimize data collected on US citizens and residents in the course of that surveillance.
The documents show that even under authorities governing the collection of foreign intelligence from foreign targets, US communications can still be collected, retained and used.
Go read the full Guardian piece here, document one (detailing the procedures used to target non-US persons) here, and document two (procedures to used by NSA to minimize data collection from U.S. persons) here. Slate will have more on the documents and Greenwald's analysis of them in a bit once we have time to digest the documents.