The Katz test of Privacy | Case Summary: Katz v. United States


Name of the Case: Katz vs. United States

Judges: Justice Stewart, Justice Marshall, Justice Douglas, Justice Brennan, Justice Harlan, Justice White, justice Black, Justice Fortas

Citation: 88 S.Ct. 507 (1967)

This is a landmark case decided in the Supreme Court of the United States of America. It was decided in 1967, making it one of the earliest cases on right to privacy. Justice Harlan’s concurrent ruling, in this case, gave birth to the ‘two-part test’ for privacy, something which is considered relevant to date.

The facts

The accused, Charles Katz, was a handicapper (a person who predicts the results of matches and depends on them). He made all communications related to these wagering agreements through a phone booth in front of his house. The FBI suspected him and so made an elaborate plan to arrest him. They tapped the phone in that booth, and so recorded all his conversations. On the basis of these recordings, he was arrested and convicted. Katz accused the state of violating his right to privacy under the fourth amendment. He also suggested that the evidence be declared inadmissible.

The law

The fourth amendment to the US constitution states as follows:

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.

The Court’s decision

Justice Stewart delivered the majority opinion. He allowed Katz’s application, overturned his conviction and went on to give a very significant definition of privacy. The petitioners (Katz) emphasised that the phone booth was a ‘constitutionally protected area’. Therefore, the recording of conversations amounted to search and seizure, which is prohibited under the fourth amendment. To this, the government argued that there was no physical penetration of the area, assuming that it was ‘constitutionally protected’. Justice Stewart plainly rejected these arguments. He gave two reasons for doing this. Firstly, the fourth amendment is not related to the protection of areas at all. Secondly, it is not a general right to privacy. It is only a protection from certain kinds of governmental intrusion.

Justice Stewart then explained that the issues were not formed correctly, and so the parties deviated from the actual matter. Whether an area is ‘constitutionally protected’ or not is not relevant to this case. The fourth amendment protects people and not places. When a person knowingly some area to the public is not protected. For example, if one calls some people for a party, they cannot later claim a breach of privacy. On the other hand, if a person seeks to preserve an area as private, even if it is generally accessible to the public, it is protected.


Therefore, when the petitioner went inside the booth and closed the door behind, he expected it to be his private space. He did not expect his conversations in there to be overheard. The Respondent’s (government) argument that he was visible through the glass door is irrelevant. Justice Stewart ruled that electronically listening to and recording the petitioner’s conversations without him knowing violated his privacy. It is a ‘search and seizure’ under the fourth amendment. The absence of any physical penetration is also irrelevant as privacy in itself is an abstract concept. The Respondents then urged that the court should ‘create a new exception’ for this case. They felt that this surveillance should not require advance authorisation as it had a probable cause. Justice Stewart rejected this argument, stating that the government had failed to meet the general condition for electronic surveillance. He, therefore, reversed Katz’s conviction.

The Katz test

Katz v Unites States is primarily remembered for Justice Harlan’s concurring opinion. While agreeing with the majority, he laid down a two-part test for determining what is protected. This came to be known as the ‘Katz test’. Firstly, the person must exhibit an actual (subjective) expectation of privacy. Secondly, that expectation should be one that society is prepared to accept as ‘reasonable’. For example, a person considers his home to be a private space. He exhibits this expectation by locking his door. The society accepts this expectation because it is reasonable.

With regard to this case, Justice Harlan explained that the fact that the phone booth was, in general, a public place is irrelevant. When the petitioner entered it and shut the door behind, it became a temporarily private space. He exhibited his expectation of privacy by shutting the door. This expectation was reasonable because it is extremely unusual for someone to overhear conversations inside a closed booth.

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