United States v. Jones presented such a challenge to the Supreme Court. The question posed was whether the installation and month-long monitoring of a GPS device attached to Jones's car constituted a violation of the Fourth Amendment's prohibition against "unreasonable searches and seizures." In prior government tracking cases, the Court applied the test from Katz v. United States , which addresses whether the individual had a reasonable expectation of privacy in the area to be searched. The trespass theory asks whether there was a physical intrusion onto a constitutionally protected area coupled with an attempt to obtain information. Justice Sotomayor agreed with both the majority and Alito's concurrence, but called for additional protection by questioning the viability of the third-party doctrine, which holds that any information voluntarily given to a third party loses all privacy protections. During this time, the device tracked Jones's movements to and from a known stash house. At trial, the prosecution relied heavily on Jones's movements derived from the GPS to connect him with a larger drug ring. Jones was ultimately convicted and sentenced to life imprisonment. The United States Court of Appeals for the District of Columbia Circuit reversed, holding that the GPS data were derived in violation of Jones's reasonable expectation of privacy under the Fourth Amendment. Because Jones's vehicle is an effect —listed in the text of the Fourth Amendment—the police's physical intrusion by attaching the GPS for tracking purposes constituted a search . The Jones Court had no doubts that the attachment of the GPS device (which required a trespass of Jones's car) would have been a search when the Fourth Amendment was adopted—when Entick was fresh in the framers' minds. This idea that the Fourth Amendment protects both privacy and property independently is infused throughout the majority opinion in Jones . The Court answered no: in addition to the physical intrusion, there must be "an attempt to find something or to obtain information." Will computer data constitute an effect ? If a police officer walks onto one's porch, is that an invasion of his house ? The Implications of Jones and Technology

As more cell phones and cars are outfitted with GPS tracking technologies, police need not physically attach a device to track its movements. Justices Alito, and his four-Justice concurrence, and Sotomayor, concurring separately, provide insight into how a future court may apply the Fourth Amendment to evolving technologies. He concluded that four weeks of tracking was a search. To say that short-term monitoring is permissible, but longer-term monitoring is not, indicates there is something about the aggregation of a person's movements that prompted these Justices to deem it a Fourth Amendment search. Justice Sotomayor's Concurrence: The Broadest Reading of the Fourth Amendment

As far as Fourth Amendment rights are concerned, Justice Sotomayor provided the broadest interpretation in Jones by joining the majority's trespass approach, openly supporting Justice Alito's privacy-based approach, and putting into question the continuing viability of the third-party doctrine—a theory many believe creates the largest gap in privacy protection, especially in the realm of technology. Because the government failed to argue that a warrant was not required or that something less than probable cause would be enough to conduct this surveillance, the Court considered the arguments forfeited. Conclusion

Nine Justices are seemingly in agreement that, based on the facts of Jones , the attachment of a GPS device to the bottom of Jones's car and tracking him for a month-long period was a constitutional search. Senator Leahy has introduced the Electronic Communications Privacy Act Amendments Act of 2011 ( S. 1011 ), which would prohibit the government from accessing or using a device to acquire geolocation information, unless it obtains a warrant based upon probable cause or a court order under Title I or Title IV of the Foreign Intelligence Surveillance Act (FISA) of 1978. Similarly, Senator Ron Wyden and Representative Jason Chaffetz have introduced identical legislation, S. 1212 and H.R.
In United States v. Jones, 132 S. Ct. 945 (2012), all nine Supreme Court Justices agreed that Jones was searched when the police attached a Global Positioning System (GPS) device to the undercarriage of his car and tracked his movements for four weeks. The Court, however, splintered on what constituted the search: the attachment of the device or the long-term monitoring. The majority held that the attachment of the GPS device and an attempt to obtain information was the violation; Justice Alito, concurring, argued that the monitoring was a violation of Jones's reasonable expectation of privacy; and Justice Sotomayor, also concurring, agreed with them both, but would provide further Fourth Amendment protections. This report will examine these three decisions in an effort to find their place in the body of existing Fourth Amendment law pertaining to privacy, property, and technology.
In Jones, the police attached a GPS tracking device to the bottom of Jones's car and monitored his movements for 28 days. At trial, the prosecution relied on Jones's movements to a stash house to tie him to a drug conspiracy. Jones was convicted and given a life sentence. The United States Court of Appeals for the District of Columbia Circuit reversed, holding that the evidence was unlawfully obtained under the Fourth Amendment. The Supreme Court agreed. The majority, speaking through Justice Scalia, explained that a physical intrusion into a constitutionally protected area, coupled with an attempt to obtain information, can constitute a violation of the Fourth Amendment. Although the Court's landmark decision in Katz v. United States, 389 U.S. 347 (1967), supposedly altered the focus of the Fourth Amendment from property to privacy, the majority argued that it left untouched traditional spheres of Fourth Amendment protection—a person and his house, papers, and effects. Because the police had invaded Jones's property—his car, which is an effect—that was all the Court needed to hold that a constitutional search had occurred.
The majority's test, however, provides little guidance in instances where the government need not physically install a device to conduct surveillance, for instance, by using cell phones or preinstalled GPS devices in vehicles. To understand how the Court may rule on these technologies, one must look to the two concurrences, which provide a more global interpretation of the Fourth Amendment. Justice Alito, writing for a four-member concurrence, would have applied the Katz privacy formulation, asserting that longer-term monitoring constitutes an invasion of privacy, whereas short-term monitoring does not. He left it to future courts to distinguish between the two. Justice Sotomayor's concurrence appears to provide the most protection, finding that both the trespass approach and the privacy-based approach should be utilized. She also questioned the rule that any information provided to a third party, which occurs in many commercial transactions like banking or computing, should lose all privacy protections.
Although all three opinions concluded that the government's action in Jones was a search, none expressly required that police get a warrant in future GPS tracking cases. (The government forfeited the argument.) Further, there is no clear indication of the level of suspicion—probable cause, reasonable suspicion, or something less—that is required to attach a GPS unit and monitor the target's movements. Additionally, there have been several bills filed in the 112th Congress, including Senator Patrick J. Leahy's Electronic Communications Privacy Act Amendment Act of 2011 (S. 1011) and Senator Ron Wyden's and Representative Jason Chaffetz's identical legislation, S. 1212 and H.R. 2168, the Geolocational Privacy and Surveillance Act (GPS bill), that would require a warrant based upon probable cause to access geolocation information.