Foreign Intelligence Surveillance Act in Light of the United States Fourth Amendment

This paper examines the evolving relationship between the Fourth Amendment’s protection against unreasonable searches and seizures and the U.S. government’s use of electronic surveillance in the name of national security. It traces the historical expansion of surveillance authority, beginning with early wiretapping cases and culminating in the enactment and evolution of the Foreign Intelligence Surveillance Act (FISA). The analysis highlights the legal tension between the executive branch’s national security prerogatives and constitutional safeguards for U.S. persons, focusing on how courts have justified exceptions to warrant requirements through doctrines such as “special needs.” It explores key cases like Katz, Keith, Truong, and In re Sealed Case, which shaped the balance between privacy rights and intelligence gathering. The paper also discusses the post-9/11 amendments to FISA under the USA PATRIOT Act, which shifted the threshold for permissible surveillance by lowering the requirement from “primary purpose” to “significant purpose” in foreign intelligence investigations. Finally, it considers ongoing legal controversies regarding warrantless surveillance programs and the implications of these developments for the future of constitutional privacy protections.