Katz v. United States

Katz v. United States

U.S. Supreme Court
389 U.S. 347 (1967)

ISSUE: Is electronically eavesdropping on a conversation occurring within a closed glass phone booth without physically penetrating the phone booth an unreasonable search as protected by the 4th Amdt.?
HOLDING: Yes, the Govt's activities in electronically listening to and recording the petitioner's words violated the privacy upon which he justifiably relied while using the phone booth and thus constituted a "search and seizure" within the meaning of the 4th Amdt.
  • FBI agents had attached an electronic listening device to the outside of a glass public phone booth
  • "Constitutionally protected area" is not necessarily the correct solution to the 4th Amdt. problem
    • 4th Amdt. protects people, not places
  • 4th Amdt. does not give a general right to privacy
  • Immaterial that he could still be seen: Katz did not shed his right to exclude simply be entering a glass phone booth where he could still be seen
    • By entering the phone booth and shutting the door, he was entitled to assume that the words he uttered were private
  • No longer need penetration: The reach of the 4th Amdt. cannot turn upon the presence or absence of a physical intrusion into any given enclosure
    • Property interests no longer control the right of the Government to search and seize
    • 4th Amdt. also applies to recording of oral statements even without a technical trespass


  • Twofold requirement for 4th Amdt. protection:
    1. That a person have exhibited an actual (subjective) expectation of privacy, and
    2. That the expectation be one that society is prepared to recognize as "reasonable."
  • Phone booth temporarily becomes a private place when one enters and shuts the door


  • 4th Amdt. refers to tangible objects ("persons, houses, papers, and effects") being protected against search, seizure, or both
  • Conversations overheard by eavesdropping are not tangible, so the 4th Amdt. should not apply to eavesdropping
  • Framers presumably knew of the practice of eavesdropping and would have specifically included protection against it if they so intended
  • Should not distort the words of the Constitution to keep it up to date
  • Majority is using the 4th Amdt. as a vehicle for holding all laws violative of the Constitution which offend the Court's broadest concept of privacy
  • I have noticed that many people are accessing this case brief, which is not surprising. Katz marks what many call the "threshold of the Fourth Amendment." So why this talk of a "threshold?" Well, the text of the Fourth Amendment prohibits unreasonable searches. But this begs the question, what is a "search" for Fourth Amendment purposes? Katz answers this question.
  • According to the Supreme Court (well, really per Justice Harlan's concurrence), a "search" occurs when law enforcement violates a person's actual, subjective expectation of privacy that society is prepared to recognize as a reasonable. Thus, one will notice that the test has two prongs: one subjective and one objective. Not surprisingly, the objective prong is the most difficult for a criminal defendant to prove, as it does not rely on simply what he himself thinks is "private."
  • Applied to the facts of Katz, off-the-wall surveillance, though there is no physical penetration of some legally-protected space, still violates the Fourth Amendment when performed without a warrant. The Court eschews reliance on physical penetration in order to bring the law up to date with "modern" technology. Katz has also been extended to prohibit wiretapping of telephone lines without a warrant. While one will learn in Smith v. Maryland that the numbers one dials on a phone are not protected by the Fourth Amendment, the contents of the call, i.e., the conversation, is protected against searches without a warrant.
  • So anytime one is confronted with a possible Fourth Amendment violation, she must apply the Katz "test": (1) Did the defendant exhibit an actual, subjective expectation of privacy? And, (2) is society prepared to recognize that expectation as reasonable?

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