The Supreme Court recently decided in United States v. Jones that placing a global positioning system (“GPS”) on a defendant’s car over a four week period constituted a “search” under the Fourth Amendment and thus required a valid search warrant. Although the Court was unanimous in its decision, the Court was split on why this Defendant’s GPS tracking by the state was considered a search under the Fourth Amendment.
Justice Scalia who wrote the majority opinion analyzed whether the defendant was protected under the Fourth Amendment and had an expectation of a proper search based on a trespass theory of property rights. In the case at bar, the Defendant owned the automobile when the state installed the GPS unit under the car. Although Scalia states that in later cases “we have deviated from that exclusively property-based approach,” he is referring specifically to Katz v. United States. In Katz Justice Harlan’s concurrence said that a “violation occurs when government officers violate a person’s reasonable expectation of privacy.” The government in the present case contended that the Defendant did not have an expectation of privacy because the automobile’s GPS only tracked the car in locations that were public. Scalia explains that the government’s contentions did not have to be addressed since the Defendant’s “fourth amendment rights [did] not rise or fall with the Katz formulation.” Additionally, Scalia expressed that the “Katz reasonable-expectation-of-privacy test has been added to, not substituted for, the common-law trespassory test.” The fact that the jeep was owned by the Defendant when the government decided to attach the GPS tracking unit to the defendant’s car was trespassory and even though the Defendant might not have a general expectation of privacy when an automobile is in a public location, guarantees against unreasonable searches and seizures of citizen’s property was the minimum protection that the Fourth Amendment afforded when it was adopted.
On the other hand, the concurrence championed by Justice Alito suggests a different approach then the general adherence to the property theory of unreasonable searches and seizures espoused by Justice Scalia. Alito suggests that a modified version of the Katz expectation-of-privacy test should be applied when analyzing if a search is considered to fall under the protection of the Fourth Amendment. He states that the “trespass-based rule was repeatedly criticized,” and that as established in United States v. Karo, “when addressing the relevance of a technical trespass, ‘an actual trespass is neither necessary nor sufficient to establish a constitutional violation.’” “The existence of a property right is but one element in determining whether expectations of privacy are legitimate.” Alito further recommends that in circumstances involving changing technology, the best solution for privacy concerns might be legislative. A legislative body is well situated to gauge “changing public attitudes, to draw detailed lines, and to balance privacy and public safety in a comprehensive way.”
Therefore, until this occurs, the best that Alito feels the Court can do in order to balance privacy and public safety needs is to “ask whether the use of GPS tracking in a particular case involved a degree of intrusion that a reasonable person would not have anticipated.” Under his approach, short-term monitoring using GPS technologies to monitor defendants in public streets would be acceptable, while long-term monitoring would impinge on expectations of privacy. In the present case, 4 weeks would be considered too long of a search. In other cases where uncertainty exists regarding whether the period of GPS surveillance constituted a Fourth Amendment search, the police according to Alito “may always seek a warrant.”
Overall, both Justice Scalia and Justice Alito both agree that the Defendant’s Fourth Amendment rights were violated and that the court of appeals correctly reversed the district courts verdict. However, their rationales for arriving to the Court’s ruling will leave future cases in doubt regarding which test to follow when the government conducts GPS surveillance on future defendants. One is founded in the common-law theory of property rights while the other opinion tries to strike a balance between both the state’s interests for safety and the citizen’s right of privacy. Going forward there still is no clear test regarding whether tracking technologies will be subject to Fourth Amendment scrutiny when implemented by the state without a warrant.
 United States v. Jones, 132 S.Ct. 945, 946 (2012).
 See id. at 953.
 Id. at 952.
 Id. at 950.
 Id. (citing Katz v. United States, 389 U.S. 347, 351 (1967) (Harlan, J., concurring).
 Jones, 132 S.Ct. at 950.
 Id. at 952.
 Id. at 953.
 Id. at 958.
 See id. at 964.
 Id. at 959.
 Id. at 960 (citing United States v. Karo, 468 U.S. 705, 713 (1984)).
 Jones, 132 S.Ct. at 960 (citing Oliver v. United States, 466 U.S. 170, 183 (1984)).
 Id. at 964.