Fourth Amendment, and thus necessitated a warrant. The Court said it was not recognizing any general right to privacy in the Fourth Amendment, and that this wiretap could have been authorized if proper procedures had been followed. This decision in Katz was later developed into the now commonly used two-prong test, adopted in Smith v. Maryland (1979), for determining whether a search has occurred for purposes of the Fourth Amendment: a person "has exhibited an actual (subjective) expectation of privacy"; and society is prepared to recognize that this expectation is (objectively) reasonable. The Supreme Court has held that the Fourth Amendment does not apply to information that is voluntarily shared with third parties. In Smith, the Court held individuals have no "legitimate expectation of privacy" regarding the telephone numbers they dial because they knowingly give that information to telephone companies when they dial a number. However, under Carpenter v. United States (2018), individuals have a reasonable expectation of privacy under the Fourth Amendment regarding cell phone records even though they themselves turned over that information to "third parties" (i.e. the cell phone companies). Prior to the Carpenter ruling, law enforcement was able to retrieve cell site location information (CSLI) that included where a cell phone user had traveled over many months and with which other cell phone users they had associated. Carpenter v. United States serves as a landmark case because it slightly narrowed the Third Party Doctrine, thus requiring law enforcement to first obtain a search warrant before receiving CSLI records. "In the 5-4 [Carpenter] decision, the Court ruled 'narrowly' in favor of privacy, finding the government had constitutionally violated Mr. Carpenter's reasonable expectation of privacy by acquiring this private information without a warrant." Following Katz, the vast majority of Fourth Amendment search cases have turned on the right to privacy, but in United States v. Jones (2012), the Court ruled that the Katz standard did not replace earlier case law, but rather, has supplemented it. In Jones, law enforcement officers had attached a GPS device on a car's exterior without Jones' knowledge or consent. The Court concluded that Jones was a bailee to the car, and so had a property interest in the car. Therefore, since the intrusion on the vehicle—a common law trespass—was for the purpose of obtaining information, the Court ruled that it was a search under the Fourth Amendment. The Court used similar "trespass" reasoning