Fourth Amendment:
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
In Katz v. United States,1 Justice White sought to preserve for a future case the possibility that in national security cases
electronic surveillance upon the authorization of the President or the Attorney General could be permissible without prior judicial approval.2 The Executive Branch then asserted the power to wiretap and to bug
in two types of national security situations, against domestic subversion and against foreign intelligence operations, first basing its authority on a theory of inherent
presidential power and then in the Supreme Court withdrawing to the argument that such surveillance was a reasonable
search and seizure and therefore valid under the Fourth Amendment. Unanimously, the Court held that at least in cases of domestic subversive investigations, compliance with the warrant provisions of the Fourth Amendment was required.3 Whether or not a search was reasonable, wrote Justice Powell for the Court, was a question which derived much of its answer from the warrant clause; except in a few narrowly circumscribed classes of situations, only those searches conducted pursuant to warrants were reasonable. The Government’s duty to preserve the national security did not override the guarantee that before government could invade the privacy of its citizens it must present to a neutral magistrate evidence sufficient to support issuance of a warrant authorizing that invasion of privacy.4 This protection was even more needed in national security cases
than in cases of ordinary
crime, the Justice continued, because the tendency of government so often is to regard opponents of its policies as a threat and hence to tread in areas protected by the First Amendment as well as by the Fourth.5 Rejected also was the argument that courts could not appreciate the intricacies of investigations in the area of national security or preserve the secrecy which is required.6
The question of the scope of the President’s constitutional powers, if any, remains judicially unsettled.7 Congress has acted, however, providing for a special court to hear requests for warrants for electronic surveillance in foreign intelligence situations, and permitting the President to authorize warrantless surveillance to acquire foreign intelligence information provided that the communications to be monitored are exclusively between or among foreign powers and there is no substantial likelihood any United States person
will be overheard.8