Trevor W. Morrison, Columbia Law School, has posted The Story of United States v. United States District Court (Keith): The Surveillance Power, a chapter in Presidential Power Stories, ed. Christopher H. Schroeder & Curtis A. Bradley (Foundation Press, 2008):
This chapter . . . tells the story of United States v. United States District Court for the Eastern District of Michigan, better known as the Keith case. Keith is the Supreme Court's first and still most important statement on the extent to which the President, acting in the interests of national security, may authorize the warrantless wiretapping or other electronic surveillance of persons within the United States. The case began as a criminal prosecution of members of the radical White Panther Party for the bombing of a CIA office in Ann Arbor, Michigan. It took a turn when the government disclosed before trial that one of the defendants had been overheard on a warrantless federal wiretap of domestic organizations that the Attorney General deemed threats to national security. This put the legality of the wiretap in issue. In what the New York Times called a stunning legal setback for the government, the Court concluded that Fourth Amendment freedoms cannot properly be guaranteed if domestic security surveillance may be conducted solely within the discretion of the Executive Branch. Thus, the Court held, a judicial warrant must issue before the government may engage in wiretapping or other electronic surveillance of domestic threats to national security. But the Court also limited its holding to cases involving the domestic aspects of national security, and express[ed] no opinion as to [the surveillance of the] activities of foreign powers or their agents. Both in what it said and what it did not say, Keith has exerted great influence upon the judicial, legislative, and executive approaches to these issues in the years since, including on Congress's passage in 1978 of the Foreign Intelligence Surveillance Act, or FISA. As of this writing, it is still the case that the Supreme Court has never upheld warrantless wiretapping within the United States, for any purpose.