Bulk collection of signals intelligence (bulk surveillance, for short) is a controversial topic. The most well known program to collect signals intelligence "in bulk" is the bulk collection of telephone metadata authorized by the Foreign Intelligence Surveillance Court under Section 215 of the Patriot Act. Opponents of the program contended the program is an unwarranted invasion of privacy, a general search of exactly the kind prohibited by the 4th Amendment to the U.S. Constitution. Supporters of the program asserted it was and is a critical tool in the nation's counterterrorist arsenal.
On May 8, 2015, the U.S. Court of Appeals for the Second Circuit held the language of this section could not plausibly be interpreted as authorizing bulk surveillance, though it did not rule on whether the program would be constitutional even with statutory justification. On June 1, Section 215 authority for this program expired, and on June 2, a new program was enacted into law under the USA Freedom Act requiring the metadata be held by phone companies. The National Security Agency lost the ability to query this metadata broadly based on prior arrangements from the Foreign Intelligence Surveillance Court, but continued to have access to specific numbers with an appropriate order issued by the Court.