The Fourth Amendment to the United States Constitution prohibits the government from engaging in ‘‘unreasonable searches and seizures.’’ Before courts ask whether a given search is ‘‘reasonable,’’ however, they must determine whether a ‘‘search’’ or a ‘‘seizure’’ occurred. The Supreme Court’s decision in Katz v. United States revolutionized the constitutional analysis of when governmental action amounts to a search and thus implicates the protections of the Fourth Amendment.
The FBI (correctly) suspected Charles Katz of being involved in an illegal gambling operation, whereby he would make calls from a public telephone to transmit information concerning bets. The FBI tapped the phone by attaching a receiver to the outside of the booth and recorded Katz’s voice during one such call. Katz was tried and convicted of the interstate communication of wagers and appealed his conviction, alleging that the conversation was illegally intercepted and, therefore, should not have been admitted against him at trial.
Justice Potter Stewart authored the majority opinion, which was joined by Chief Justice Earl Warren and Justices William Douglas, John Harlan, William Brennan, Byron White, and Abe Fortas. The Court held that tapping the phone was a search, even though there had been no entry into the phone booth. Thus, the opinion rejected the ‘‘trespass’’ doctrine, which had prevailed until Katz in cases such as United States v. Olmstead, whereby government action did not trigger the Fourth Amendment unless there was a physical invasion of a private space.
Although the Court was clear that physical trespass was no longer the sole factor for determining whether a search occurred, it was less clear about how future cases should be resolved. It stated that someone who enters a phone booth ‘‘shuts the door behind him, and pays the toll that permits him to place a call is surely entitled to assume that the words he utters into the mouthpiece will not be broadcast to the world.’’ And the Court also stated that something that a person ‘‘knowingly exposes to the public’’ is not private, and, therefore, police discovery of it does not constitute a search. But these statements were unhelpful in providing police and lower courts with a test to apply to future cases.
That test came in Justice Harlan’s concurrence, which has routinely been applied by the Supreme Court in subsequent decades. Under the test stated by Justice Harlan, a search occurs whenever the government invades an individual’s ‘‘reasonable expectation of privacy.’’ That question, in turn, is composed of two subsidiary questions: whether the individual had an expectation of privacy in the area searched, and whether society treats that expectation of privacy as ‘‘reasonable’’ or ‘‘legitimate.’’ Justice Harlan’s test has been enormously influential but raises difficult analytical problems. Most seriously, it invites the Justices to write their ideas of privacy into constitutional law in determining when a particular expectation of privacy is ‘‘reasonable.’’ As Justice Scalia wryly commented in Minnesota v. Carter, ‘‘unsurprisingly, those ‘actual (subjective) expectation[s] of privacy’ ‘that society is prepared to recognize as ‘‘reasonable,’’’ bear an uncanny resemblance to those expectations of privacy that this Court considers reasonable.
Having determined that a ‘‘search’’ occurred, the Court then had to assess whether the ‘‘search’’ was ‘‘reasonable.’’ The Court held that the police’s failure to obtain a warrant made the search unreasonable, and for that reason the Court reversed Katz’s conviction. The Court maintained that searches conducted ‘‘without prior approval by judge or magistrate[s] are per se unreasonable under the Fourth Amendment— subject only to a few specifically established and welldelineated exceptions.’’ Because no exception was applicable here, the search was unconstitutional.
Justice Hugo Black dissented. In his view, the Fourth Amendment protects against only tangible items—things that can be ‘‘searched’’ or ‘‘seized.’’ Because a conversation is not tangible, he would have held that the Fourth Amendment does not regulate police eavesdropping, electronic or otherwise.
Post-Katz cases have asked whether certain expectations of privacy are ‘‘reasonable.’’ United States v. White held that a person has no reasonable expectation of privacy in conversations if the other party to the conversation consents to its being recorded or transmitted to others. California v. Greenwood held that one has no legitimate expectation of privacy in garbage left on the curb. United States v. Miller held that one’s bank records are not something about which one has a reasonable expectation of privacy, and Smith v. Maryland applied Miller to hold that there is no reasonable expectation of privacy in the numbers one dials on a home telephone. United States v. Place and Illinois v. Caballes held a trained dog’s sniff for the scent of contraband is not a search. United States v. Knotts held that police use of a beeper to trail a suspect along public roads infringed on no reasonable expectation of privacy, but United States v. Karo did find a reasonable expectation of privacy if a similar beeper disclosed information about movements in the interior of a home, and Karo was expanded in Kyllo v. United States to cover thermal imaging of houses.
References and Further Reading
Cases and Statutes Cited
See also Exclusionary Rule; Privacy; Search (General Definition)