beyond the normal need for law enforcement'. ... When such 'special needs' are alleged, courts must undertake a context-specific inquiry, examining closely the competing private and public interests advanced by the parties." The amendment applies to governmental searches and seizures, but not those done by private citizens or organizations who are not acting on behalf of a government. In Ontario v. Quon (2010), the Court applied the amendment to a municipal government in its capacity as an employer, ruling that the City of Ontario had not violated the Fourth Amendment rights of city police officers by obtaining from the communications company and reviewing transcripts of text messages sent using government-provided pagers. Search One threshold question in the Fourth Amendment jurisprudence is whether a "search" has occurred. Initial Fourth Amendment case law hinged on a citizen's property rights—that is, when the government physically intrudes on "persons, houses, papers, or effects" for the purpose of obtaining information, a "search" within the original meaning of the Fourth Amendment, has occurred. Early 20th-century Court decisions, such as Olmstead v. United States (1928), held that Fourth Amendment rights applied in cases of physical intrusion, but not to other forms of police surveillance (e.g., wiretaps). In Silverman v. United States (1961), the Court stated of the amendment that "at the very core stands the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion". Fourth Amendment protections expanded significantly with Katz v. United States (1967). In Katz, the Supreme Court expanded that focus to embrace an individual's right to privacy, and ruled that a search had occurred when the government wiretapped a telephone booth using a microphone attached to the outside of the glass. While there was no physical intrusion into the booth, the Court reasoned that: 1) Katz, by entering the booth and shutting the door behind him, had exhibited his expectation that "the words he utters into the mouthpiece will not be broadcast to the world"; and 2) society believes that his expectation was reasonable. Justice Potter Stewart wrote in the majority opinion that "the Fourth Amendment protects people, not places". A "search" occurs for purposes of the Fourth Amendment when the government violates a person's "reasonable expectation of privacy". Katz's reasonable expectation of privacy thus provided the basis to rule that the government's intrusion, though electronic rather than physical, was a search covered by the