In Katz v. United States (1967) 389 U.S. 347, the United States Supreme Court held a Fourth Amendment violation occurred when federal agents planted an electronic listening and recording device outside a public telephone booth and overheard the defendant transmitting wagering information. (Id. at pp. 348, 359.) The United States Supreme Court also held that "the Government's activities in electronically listening to and recording the petitioner's words in a public telephone booth violated the privacy upon which he justifiably relied while using the telephone booth and thus constituted a 'search and seizure' within the meaning of the Fourth Amendment...." ( Id., at p. 353.) Although the majority opinion in Katz did not use the phrase "reasonable expectation of privacy," Justice Harlan in concurrence said: "As the Court's opinion states, 'the Fourth Amendment protects people, not places.' The question, however, is what protection it affords to those people. Generally, the answer to that question requires reference to a 'place.' My understanding of the rule that has emerged from prior decisions is that there is a twofold requirement, first that a person have exhibited an actual (subjective) expectation of privacy and, second, that the expectation be one that society is prepared to recognize as 'reasonable.'" ( Id., at p. 361.)