"Since 2008, the National Security Agency (NSA) and other members of the U.S. Intelligence Community have relied on Section 702 of the Foreign Intelligence Surveillance Act (FISA) to conduct surveillance on specific foreign targets located outside the United States to acquire critical intelligence on issues ranging from international terrorism to cybersecurity. After a comprehensive review of mission needs, current technological constraints, United States person privacy interests, and certain difficulties in implementation, NSA has decided to stop some of its activities conducted under Section 702.
While the Foreign Intelligence Surveillance Court (FISC) was considering the government's annual application to renew the Section 702 certifications, NSA reported several earlier, inadvertent compliance incidents related to queries involving U.S. person information in 702 "upstream" internet collection. Although the incidents were not willful, NSA was required to, and did, report them to both Congress and the FISC. The court issued two extensions of the government's renewal application in order to receive additional information from the government about this issue and the government's plan to resolve it. The previous year's certifications remained in effect during these extension periods.
During the extension period, NSA undertook a broad review of its Section 702 program. Under Section 702, NSA collects internet communications in two ways: "downstream" (previously referred to as PRISM) and "upstream." Under downstream collection, NSA acquires communications "to or from" a Section 702 selector (such as an email address). Under upstream collection, NSA acquires communications "to, from, or about" a Section 702 selector. An example of an "about" email communication is one that includes the targeted email address in the text or body of the email, even though the email is between two persons who are not themselves targets. The independent Privacy and Civil Liberties Oversight Board described these collection methods in an exhaustive report published in 2014."
https://www.nsa.gov/news-features/press-room/Article/1618699/nsa-stops-certain-section-702-upstream-activities/