In applying the Katz analysis to this case, it is important to begin by specifying precisely the nature of the state activity that is challenged. Those who disclose certain facts to a bank or phone company for a limited business purpose need not assume that this information will be released to other persons for other purposes. What about an online Bar Exam. But even assuming, as I do not, that individuals "typically know" that a phone company monitors calls for internal reasons, ante, at 743,1 it does not follow that they expect this information to be made available to the public in general or the government in particular. This is information that he voluntarily 421, 58 L.Ed.2d 387. The police did not get a warrant or court order before having the pen register installed. Similarly, if a refugee from a totalitarian country, unaware of this Nation's traditions, erroneously assumed that police were continuously monitoring his telephone conversations, a subjective expectation of privacy regarding the contents of his calls might be lacking as well. 2579-2580. . By tracing the license plate number, police learned that the car was registered in the name of petitioner, Michael Lee Smith. 515 (SDNY 1978). Katz v. United States, 389 U.S. 347, 88 S.Ct. Ante, at 744,745. The Court concludes that because individuals have no actual or legitimate expectation of privacy in information they voluntarily relinquish to telephone companies, the use of pen registers by government agents is immune from Fourth Amendment scrutiny. Because the Government's monitoring of Katz' conversation "violated the privacy upon which he justifiably relied while using the telephone booth," the Court held that it "constituted a 'search and seizure' within the meaning of the Fourth Amendment." Further, that information is an integral part of the telephonic communication that under Katz is entitled to constitutional protection, whether or not it is captured by a trespass into such an area. Ante, at 743. the meaning of the Fourth Amendment, and hence no warrant was required. United States v. New York Tel. E. g., Rakas v. Illinois, 439 U.S. 128, 143, 99 S.Ct. This case presents the question whether the installation and use of a pen register1 constitutes a "search" within the meaning of the Fourth Amendment,2 made applicable to the States through the Fourteenth Amendment. Regardless of the phone company's election, petitioner voluntarily conveyed to it information that it had facilities for recording and that it was free to record. But that observation no more than describes the basic nature of telephone calls. Co. v. United States, 434 U.S. 1008, 98 S.Ct. 108, 110-111 (1970). Note: Pp. The Court & Tel. The court has found no 814, 816 (Md.1978); Note, 60 Cornell L.Rev., at 1029-1030, n. 11; Claerhout, The Pen Register, 20 Drake L.Rev. United States v. New York Tel. privacy regarding the numbers he dialed on his phone because those More fundamentally, to make risk analysis dispositive in assessing the reasonableness of privacy expectations would allow the government to define the scope of Fourth Amendment protections. By contrast here, unless a person is prepared to forgo use of what for many has become a personal or professional necessity, he cannot help but accept the risk of surveillance. Id., at 72. A similar reasoning applies to bank records. Electronic equipment, by contrast can "remember" only those numbers it is programmed to record, and telephone companies, in view of their present billing practices, usually do not record local calls. Id., at 63. McDonough was robbed and began receiving threatening phone calls from a 507, 19 L.Ed.2d 576. Record 14; Tr. 1431, 59 L.Ed.2d 639 (1979); Halperin v. Kissinger, 434 F.Supp. Reasoning: 1. Statement of the Facts: Both Brady and Boblit were suspected of murder. 408, 413, 17 L.Ed.2d 374 (1966); Lopez v. United States, 373 U.S. 427, 83 S.Ct. A telephone call simply cannot be made without the use of telephone company property and without payment to the company for the service. 364, 366 n. 1, 54 L.Ed.2d 376 (1977). Co., 434 U.S., at 162, 98 S.Ct., at 367. . 1619, 1629-1630, 48 L.Ed.2d 71 (1976) (MARSHALL, J., dissenting), I respectfully dissent. Petitioner was arrested, and a six-man lineup was held on March 19. The register revealed that on March 17 a call was placed from petitioner's home to McDonough's phone. " Katz v. United States, 389 U.S., at 361, 88 S.Ct., at 516.