◆ SpookStack

the vast majority of cases it is impossible."' W.H. Parker, Surveillance by Wiretap or. Dictograph: Threat or Protection?, 42 Cal. L.Rev. 727, 734 (1954). Or as one of the Special Agents involved in the investigation of Jones testified at trial: "Physical. surveillance is actually hard, you know. There's always chances of getting spotted, you know, the same vehicle always around, so we decided to use GPs technology." Tr.. 11/21/07 at 114. FN* "The darts consist of a miniaturized GPS receiver, radio transmitter, and battery embedded in a sticky compound material. When fired at a vehicle, the compound adheres to the target, and thereafter permits remote real-time tracking of the target from police headquarters." Renee McDonald Hutchins, Tied Up in Knotts? GPS Technology and the Fourth Amendment, 55 UCLA L.Rev. 409, 419 (2007); see also Richard Winton, LAPD Pursues High-Tech End to High-Speed Chases, L.A. Times, Feb. 3, 2006, at B1. GPS darts are used in exigent circumstances and for only as long as it takes to interdict the subject driver without having to engage in a high-speed chase on a public way. *16 The Government's argument-that our holding the use of the GPS device was a search necessarily implicates prolonged visual surveillance-fails even on its own terms. That argument relies implicitly upon an assumption rejected explicitly in Kyllo, to wit, that the means used to uncover private information play no role in determining whether a. police action frustrates a person's reasonable expectation of privacy; when it comes to the. Fourth Amendment, means do matter. See 533 U.S. at 35 n.2 ("The fact that equivalent information could sometimes be obtained by other means does not make lawful the use of. means that violate the Fourth Amendment'). For example, the police may without a warrant record one's conversations by planting an undercover agent in one's midst, Lopez v. United States, 373 U.S. 427, 429 (1963), but may not do the same by wiretapping one's. phone, even "without any trespass," Katz, 389 U.S. 347, 353 (1967). Quite simply, in the former case one's reasonable expectation of control over one's personal information would not be defeated; in the latter it would be. See Reporters Committee, 489 U.S. at 763 ("both the common law and the literal understandings of privacy encompass the individual's control of information concerning his or her person'). This case does not require us to, and therefore we do not, decide whether a hypothetical instance of prolonged visual surveillance would be a search subject to the warrant requirement of the Fourth Amendment. As the Supreme Court said in Dow Chemical Co. v. United States, "Fourth Amendment cases must be decided on the facts of each case, not by extravagant generalizations. 'We have never held that potential, as opposed to actual, invasions of privacy constitute searches for purposes of the Fourth Amendment.' " 476 U.S. 227, 238 n.5 (1986) (quoting United States v. Karo, 468 U.S. 705, 712 (1984)); see also City of Ontario v. Quon, 130 S.Ct. 2619, 2629 (2010) ("Prudence counsels caution before the facts in the instant case are used to establish far- reaching premises that define the existence, and extent, of privacy expectations'). By the same token, we refuse to hold this "search is not a search," Kyllo, 533 U.S. at 32, merely because a contrary holding might at first blush seem to implicate a different but intuitively permissible practice. See Nat'l Fed'n of Fed. Employees y. Weinberger, 818 F.2d 935, 942 (D.C.Cir.1987) ("Few legal issues in the Fourth Amendment domain are so pure that they do not turn on any facts or circumstances peculiar to the case"). Instead, 21 TTT