8 CARPENTER v. UNITED STATES Opinion of the Court privacy in his movements from one place to another.” Id., at 281, 282. Since the movements of the vehicle and its final destination had been “voluntarily conveyed to anyone who wanted to look,” Knotts could not assert a privacy interest in the information obtained. Id., at 281. This Court in Knotts, however, was careful to distinguish between the rudimentary tracking facilitated by the beeper and more sweeping modes of surveillance. The Court emphasized the “limited use which the government made of the signals from this particular beeper” during a discrete “automotive journey.” Id., at 284, 285. Significantly, the Court reserved the question whether “different constitutional principles may be applicable” if “twenty-four hour surveillance of any citizen of this country [were] possible.” Id., at 283–284. Three decades later, the Court considered more sophisticated surveillance of the sort envisioned in Knotts and found that different principles did indeed apply. In United States v. Jones, FBI agents installed a GPS tracking device on Jones’s vehicle and remotely monitored the vehicle’s movements for 28 days. The Court decided the case based on the Government’s physical trespass of the vehicle. 565 U. S., at 404–405. At the same time, five Justices agreed that related privacy concerns would be raised by, for example, “surreptitiously activating a stolen vehicle detection system” in Jones’s car to track Jones himself, or conducting GPS tracking of his cell phone. Id., at 426, 428 (ALITO, J., concurring in judgment); id., at 415 (SOTOMAYOR, J., concurring). Since GPS monitoring of a vehicle tracks “every movement” a person makes in that vehicle, the concurring Justices concluded that “longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy”—regardless whether those movements were disclosed to the public at large. Id., at 430 (opinion of ALITO, J.); id., at 415 (opinion of